From: Ash Wilding <ash.j.wilding@gmail.com>
This patch pulls in Linux's atomics helpers for arm32 and arm64, and
their dependencies, as-is.
Note that Linux's arm32 atomics helpers use the READ_ONCE() and
WRITE_ONCE() macros defined in <asm-generic/rwonce.h>, while Linux's
arm64 atomics helpers use __READ_ONCE() and __WRITE_ONCE().
The only difference is that the __* versions skip checking whether the
object being accessed is the same size as a native C type (e.g. char,
int, long, etc). Given the arm32 helpers are using the macros to access
an atomic_t's counter member, which is an int, we can skip this check by
using the __* versions like the arm64 code does.
I mention this here because it forms the first part of my justification
for *not* copying Linux's <linux/compiler_types.h> to Xen; the size
check described above is performed by __native_word() defined in that
header.
The second part of my justification may be more contentious; as you'll
see in the next patch, I intend to drop the __unqual_scalar_typeof()
calls in __READ_ONCE() and __WRITE_ONCE(). This is because the pointer
to the atomic_t's counter member is always a basic (int *) so we don't
need this, and dropping it means we can avoid having to port Linux's
<linux/compiler_types.h>.
If people are against this approach, please bear in mind that the
current version of __unqual_scalar_typeof() in <linux/compiler_types.h>
was actually the reason for Linux upgrading the minimum GCC version
required to 4.9 earlier this year so that they can guarantee C11
_Generic support [1].
So if we do want to take Linux's <linux/compiler_types.h> we'll either
need to:
A) bump up the minimum required version of GCC to 4.9 to match
that required by Linux; in the Xen README we currently state
GCC 4.8 for Arm and GCC 4.1.2_20070115 for x86.
or:
B) mix-and-match an older version of Linux's <linux/compiler_types.h>
with the other headers taken from a newer version of Linux.
Thoughts?
[1] https://lkml.org/lkml/2020/7/8/1308
Signed-off-by: Ash Wilding <ash.j.wilding@gmail.com>
---
xen/include/asm-arm/arm32/atomic.h | 507 +++++++++++++++++++++++
xen/include/asm-arm/arm32/cmpxchg.h | 279 +++++++++++++
xen/include/asm-arm/arm64/atomic.h | 228 ++++++++++
xen/include/asm-arm/arm64/atomic_ll_sc.h | 353 ++++++++++++++++
xen/include/asm-arm/arm64/atomic_lse.h | 419 +++++++++++++++++++
xen/include/asm-arm/arm64/cmpxchg.h | 285 +++++++++++++
xen/include/asm-arm/arm64/lse.h | 48 +++
xen/include/xen/rwonce.h | 90 ++++
8 files changed, 2209 insertions(+)
create mode 100644 xen/include/asm-arm/arm32/atomic.h
create mode 100644 xen/include/asm-arm/arm32/cmpxchg.h
create mode 100644 xen/include/asm-arm/arm64/atomic.h
create mode 100644 xen/include/asm-arm/arm64/atomic_ll_sc.h
create mode 100644 xen/include/asm-arm/arm64/atomic_lse.h
create mode 100644 xen/include/asm-arm/arm64/cmpxchg.h
create mode 100644 xen/include/asm-arm/arm64/lse.h
create mode 100644 xen/include/xen/rwonce.h
diff --git a/xen/include/asm-arm/arm32/atomic.h b/xen/include/asm-arm/arm32/atomic.h
new file mode 100644
index 0000000000..ac6338dd9b
--- /dev/null
+++ b/xen/include/asm-arm/arm32/atomic.h
@@ -0,0 +1,507 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * arch/arm/include/asm/atomic.h
+ *
+ * Copyright (C) 1996 Russell King.
+ * Copyright (C) 2002 Deep Blue Solutions Ltd.
+ */
+#ifndef __ASM_ARM_ATOMIC_H
+#define __ASM_ARM_ATOMIC_H
+
+#include <linux/compiler.h>
+#include <linux/prefetch.h>
+#include <linux/types.h>
+#include <linux/irqflags.h>
+#include <asm/barrier.h>
+#include <asm/cmpxchg.h>
+
+#ifdef __KERNEL__
+
+/*
+ * On ARM, ordinary assignment (str instruction) doesn't clear the local
+ * strex/ldrex monitor on some implementations. The reason we can use it for
+ * atomic_set() is the clrex or dummy strex done on every exception return.
+ */
+#define atomic_read(v) READ_ONCE((v)->counter)
+#define atomic_set(v,i) WRITE_ONCE(((v)->counter), (i))
+
+#if __LINUX_ARM_ARCH__ >= 6
+
+/*
+ * ARMv6 UP and SMP safe atomic ops. We use load exclusive and
+ * store exclusive to ensure that these are atomic. We may loop
+ * to ensure that the update happens.
+ */
+
+#define ATOMIC_OP(op, c_op, asm_op) \
+static inline void atomic_##op(int i, atomic_t *v) \
+{ \
+ unsigned long tmp; \
+ int result; \
+ \
+ prefetchw(&v->counter); \
+ __asm__ __volatile__("@ atomic_" #op "\n" \
+"1: ldrex %0, [%3]\n" \
+" " #asm_op " %0, %0, %4\n" \
+" strex %1, %0, [%3]\n" \
+" teq %1, #0\n" \
+" bne 1b" \
+ : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) \
+ : "r" (&v->counter), "Ir" (i) \
+ : "cc"); \
+} \
+
+#define ATOMIC_OP_RETURN(op, c_op, asm_op) \
+static inline int atomic_##op##_return_relaxed(int i, atomic_t *v) \
+{ \
+ unsigned long tmp; \
+ int result; \
+ \
+ prefetchw(&v->counter); \
+ \
+ __asm__ __volatile__("@ atomic_" #op "_return\n" \
+"1: ldrex %0, [%3]\n" \
+" " #asm_op " %0, %0, %4\n" \
+" strex %1, %0, [%3]\n" \
+" teq %1, #0\n" \
+" bne 1b" \
+ : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) \
+ : "r" (&v->counter), "Ir" (i) \
+ : "cc"); \
+ \
+ return result; \
+}
+
+#define ATOMIC_FETCH_OP(op, c_op, asm_op) \
+static inline int atomic_fetch_##op##_relaxed(int i, atomic_t *v) \
+{ \
+ unsigned long tmp; \
+ int result, val; \
+ \
+ prefetchw(&v->counter); \
+ \
+ __asm__ __volatile__("@ atomic_fetch_" #op "\n" \
+"1: ldrex %0, [%4]\n" \
+" " #asm_op " %1, %0, %5\n" \
+" strex %2, %1, [%4]\n" \
+" teq %2, #0\n" \
+" bne 1b" \
+ : "=&r" (result), "=&r" (val), "=&r" (tmp), "+Qo" (v->counter) \
+ : "r" (&v->counter), "Ir" (i) \
+ : "cc"); \
+ \
+ return result; \
+}
+
+#define atomic_add_return_relaxed atomic_add_return_relaxed
+#define atomic_sub_return_relaxed atomic_sub_return_relaxed
+#define atomic_fetch_add_relaxed atomic_fetch_add_relaxed
+#define atomic_fetch_sub_relaxed atomic_fetch_sub_relaxed
+
+#define atomic_fetch_and_relaxed atomic_fetch_and_relaxed
+#define atomic_fetch_andnot_relaxed atomic_fetch_andnot_relaxed
+#define atomic_fetch_or_relaxed atomic_fetch_or_relaxed
+#define atomic_fetch_xor_relaxed atomic_fetch_xor_relaxed
+
+static inline int atomic_cmpxchg_relaxed(atomic_t *ptr, int old, int new)
+{
+ int oldval;
+ unsigned long res;
+
+ prefetchw(&ptr->counter);
+
+ do {
+ __asm__ __volatile__("@ atomic_cmpxchg\n"
+ "ldrex %1, [%3]\n"
+ "mov %0, #0\n"
+ "teq %1, %4\n"
+ "strexeq %0, %5, [%3]\n"
+ : "=&r" (res), "=&r" (oldval), "+Qo" (ptr->counter)
+ : "r" (&ptr->counter), "Ir" (old), "r" (new)
+ : "cc");
+ } while (res);
+
+ return oldval;
+}
+#define atomic_cmpxchg_relaxed atomic_cmpxchg_relaxed
+
+static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
+{
+ int oldval, newval;
+ unsigned long tmp;
+
+ smp_mb();
+ prefetchw(&v->counter);
+
+ __asm__ __volatile__ ("@ atomic_add_unless\n"
+"1: ldrex %0, [%4]\n"
+" teq %0, %5\n"
+" beq 2f\n"
+" add %1, %0, %6\n"
+" strex %2, %1, [%4]\n"
+" teq %2, #0\n"
+" bne 1b\n"
+"2:"
+ : "=&r" (oldval), "=&r" (newval), "=&r" (tmp), "+Qo" (v->counter)
+ : "r" (&v->counter), "r" (u), "r" (a)
+ : "cc");
+
+ if (oldval != u)
+ smp_mb();
+
+ return oldval;
+}
+#define atomic_fetch_add_unless atomic_fetch_add_unless
+
+#else /* ARM_ARCH_6 */
+
+#ifdef CONFIG_SMP
+#error SMP not supported on pre-ARMv6 CPUs
+#endif
+
+#define ATOMIC_OP(op, c_op, asm_op) \
+static inline void atomic_##op(int i, atomic_t *v) \
+{ \
+ unsigned long flags; \
+ \
+ raw_local_irq_save(flags); \
+ v->counter c_op i; \
+ raw_local_irq_restore(flags); \
+} \
+
+#define ATOMIC_OP_RETURN(op, c_op, asm_op) \
+static inline int atomic_##op##_return(int i, atomic_t *v) \
+{ \
+ unsigned long flags; \
+ int val; \
+ \
+ raw_local_irq_save(flags); \
+ v->counter c_op i; \
+ val = v->counter; \
+ raw_local_irq_restore(flags); \
+ \
+ return val; \
+}
+
+#define ATOMIC_FETCH_OP(op, c_op, asm_op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ unsigned long flags; \
+ int val; \
+ \
+ raw_local_irq_save(flags); \
+ val = v->counter; \
+ v->counter c_op i; \
+ raw_local_irq_restore(flags); \
+ \
+ return val; \
+}
+
+static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
+{
+ int ret;
+ unsigned long flags;
+
+ raw_local_irq_save(flags);
+ ret = v->counter;
+ if (likely(ret == old))
+ v->counter = new;
+ raw_local_irq_restore(flags);
+
+ return ret;
+}
+
+#define atomic_fetch_andnot atomic_fetch_andnot
+
+#endif /* __LINUX_ARM_ARCH__ */
+
+#define ATOMIC_OPS(op, c_op, asm_op) \
+ ATOMIC_OP(op, c_op, asm_op) \
+ ATOMIC_OP_RETURN(op, c_op, asm_op) \
+ ATOMIC_FETCH_OP(op, c_op, asm_op)
+
+ATOMIC_OPS(add, +=, add)
+ATOMIC_OPS(sub, -=, sub)
+
+#define atomic_andnot atomic_andnot
+
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op, c_op, asm_op) \
+ ATOMIC_OP(op, c_op, asm_op) \
+ ATOMIC_FETCH_OP(op, c_op, asm_op)
+
+ATOMIC_OPS(and, &=, and)
+ATOMIC_OPS(andnot, &= ~, bic)
+ATOMIC_OPS(or, |=, orr)
+ATOMIC_OPS(xor, ^=, eor)
+
+#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
+#undef ATOMIC_OP_RETURN
+#undef ATOMIC_OP
+
+#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
+
+#ifndef CONFIG_GENERIC_ATOMIC64
+typedef struct {
+ s64 counter;
+} atomic64_t;
+
+#define ATOMIC64_INIT(i) { (i) }
+
+#ifdef CONFIG_ARM_LPAE
+static inline s64 atomic64_read(const atomic64_t *v)
+{
+ s64 result;
+
+ __asm__ __volatile__("@ atomic64_read\n"
+" ldrd %0, %H0, [%1]"
+ : "=&r" (result)
+ : "r" (&v->counter), "Qo" (v->counter)
+ );
+
+ return result;
+}
+
+static inline void atomic64_set(atomic64_t *v, s64 i)
+{
+ __asm__ __volatile__("@ atomic64_set\n"
+" strd %2, %H2, [%1]"
+ : "=Qo" (v->counter)
+ : "r" (&v->counter), "r" (i)
+ );
+}
+#else
+static inline s64 atomic64_read(const atomic64_t *v)
+{
+ s64 result;
+
+ __asm__ __volatile__("@ atomic64_read\n"
+" ldrexd %0, %H0, [%1]"
+ : "=&r" (result)
+ : "r" (&v->counter), "Qo" (v->counter)
+ );
+
+ return result;
+}
+
+static inline void atomic64_set(atomic64_t *v, s64 i)
+{
+ s64 tmp;
+
+ prefetchw(&v->counter);
+ __asm__ __volatile__("@ atomic64_set\n"
+"1: ldrexd %0, %H0, [%2]\n"
+" strexd %0, %3, %H3, [%2]\n"
+" teq %0, #0\n"
+" bne 1b"
+ : "=&r" (tmp), "=Qo" (v->counter)
+ : "r" (&v->counter), "r" (i)
+ : "cc");
+}
+#endif
+
+#define ATOMIC64_OP(op, op1, op2) \
+static inline void atomic64_##op(s64 i, atomic64_t *v) \
+{ \
+ s64 result; \
+ unsigned long tmp; \
+ \
+ prefetchw(&v->counter); \
+ __asm__ __volatile__("@ atomic64_" #op "\n" \
+"1: ldrexd %0, %H0, [%3]\n" \
+" " #op1 " %Q0, %Q0, %Q4\n" \
+" " #op2 " %R0, %R0, %R4\n" \
+" strexd %1, %0, %H0, [%3]\n" \
+" teq %1, #0\n" \
+" bne 1b" \
+ : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) \
+ : "r" (&v->counter), "r" (i) \
+ : "cc"); \
+} \
+
+#define ATOMIC64_OP_RETURN(op, op1, op2) \
+static inline s64 \
+atomic64_##op##_return_relaxed(s64 i, atomic64_t *v) \
+{ \
+ s64 result; \
+ unsigned long tmp; \
+ \
+ prefetchw(&v->counter); \
+ \
+ __asm__ __volatile__("@ atomic64_" #op "_return\n" \
+"1: ldrexd %0, %H0, [%3]\n" \
+" " #op1 " %Q0, %Q0, %Q4\n" \
+" " #op2 " %R0, %R0, %R4\n" \
+" strexd %1, %0, %H0, [%3]\n" \
+" teq %1, #0\n" \
+" bne 1b" \
+ : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) \
+ : "r" (&v->counter), "r" (i) \
+ : "cc"); \
+ \
+ return result; \
+}
+
+#define ATOMIC64_FETCH_OP(op, op1, op2) \
+static inline s64 \
+atomic64_fetch_##op##_relaxed(s64 i, atomic64_t *v) \
+{ \
+ s64 result, val; \
+ unsigned long tmp; \
+ \
+ prefetchw(&v->counter); \
+ \
+ __asm__ __volatile__("@ atomic64_fetch_" #op "\n" \
+"1: ldrexd %0, %H0, [%4]\n" \
+" " #op1 " %Q1, %Q0, %Q5\n" \
+" " #op2 " %R1, %R0, %R5\n" \
+" strexd %2, %1, %H1, [%4]\n" \
+" teq %2, #0\n" \
+" bne 1b" \
+ : "=&r" (result), "=&r" (val), "=&r" (tmp), "+Qo" (v->counter) \
+ : "r" (&v->counter), "r" (i) \
+ : "cc"); \
+ \
+ return result; \
+}
+
+#define ATOMIC64_OPS(op, op1, op2) \
+ ATOMIC64_OP(op, op1, op2) \
+ ATOMIC64_OP_RETURN(op, op1, op2) \
+ ATOMIC64_FETCH_OP(op, op1, op2)
+
+ATOMIC64_OPS(add, adds, adc)
+ATOMIC64_OPS(sub, subs, sbc)
+
+#define atomic64_add_return_relaxed atomic64_add_return_relaxed
+#define atomic64_sub_return_relaxed atomic64_sub_return_relaxed
+#define atomic64_fetch_add_relaxed atomic64_fetch_add_relaxed
+#define atomic64_fetch_sub_relaxed atomic64_fetch_sub_relaxed
+
+#undef ATOMIC64_OPS
+#define ATOMIC64_OPS(op, op1, op2) \
+ ATOMIC64_OP(op, op1, op2) \
+ ATOMIC64_FETCH_OP(op, op1, op2)
+
+#define atomic64_andnot atomic64_andnot
+
+ATOMIC64_OPS(and, and, and)
+ATOMIC64_OPS(andnot, bic, bic)
+ATOMIC64_OPS(or, orr, orr)
+ATOMIC64_OPS(xor, eor, eor)
+
+#define atomic64_fetch_and_relaxed atomic64_fetch_and_relaxed
+#define atomic64_fetch_andnot_relaxed atomic64_fetch_andnot_relaxed
+#define atomic64_fetch_or_relaxed atomic64_fetch_or_relaxed
+#define atomic64_fetch_xor_relaxed atomic64_fetch_xor_relaxed
+
+#undef ATOMIC64_OPS
+#undef ATOMIC64_FETCH_OP
+#undef ATOMIC64_OP_RETURN
+#undef ATOMIC64_OP
+
+static inline s64 atomic64_cmpxchg_relaxed(atomic64_t *ptr, s64 old, s64 new)
+{
+ s64 oldval;
+ unsigned long res;
+
+ prefetchw(&ptr->counter);
+
+ do {
+ __asm__ __volatile__("@ atomic64_cmpxchg\n"
+ "ldrexd %1, %H1, [%3]\n"
+ "mov %0, #0\n"
+ "teq %1, %4\n"
+ "teqeq %H1, %H4\n"
+ "strexdeq %0, %5, %H5, [%3]"
+ : "=&r" (res), "=&r" (oldval), "+Qo" (ptr->counter)
+ : "r" (&ptr->counter), "r" (old), "r" (new)
+ : "cc");
+ } while (res);
+
+ return oldval;
+}
+#define atomic64_cmpxchg_relaxed atomic64_cmpxchg_relaxed
+
+static inline s64 atomic64_xchg_relaxed(atomic64_t *ptr, s64 new)
+{
+ s64 result;
+ unsigned long tmp;
+
+ prefetchw(&ptr->counter);
+
+ __asm__ __volatile__("@ atomic64_xchg\n"
+"1: ldrexd %0, %H0, [%3]\n"
+" strexd %1, %4, %H4, [%3]\n"
+" teq %1, #0\n"
+" bne 1b"
+ : "=&r" (result), "=&r" (tmp), "+Qo" (ptr->counter)
+ : "r" (&ptr->counter), "r" (new)
+ : "cc");
+
+ return result;
+}
+#define atomic64_xchg_relaxed atomic64_xchg_relaxed
+
+static inline s64 atomic64_dec_if_positive(atomic64_t *v)
+{
+ s64 result;
+ unsigned long tmp;
+
+ smp_mb();
+ prefetchw(&v->counter);
+
+ __asm__ __volatile__("@ atomic64_dec_if_positive\n"
+"1: ldrexd %0, %H0, [%3]\n"
+" subs %Q0, %Q0, #1\n"
+" sbc %R0, %R0, #0\n"
+" teq %R0, #0\n"
+" bmi 2f\n"
+" strexd %1, %0, %H0, [%3]\n"
+" teq %1, #0\n"
+" bne 1b\n"
+"2:"
+ : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
+ : "r" (&v->counter)
+ : "cc");
+
+ smp_mb();
+
+ return result;
+}
+#define atomic64_dec_if_positive atomic64_dec_if_positive
+
+static inline s64 atomic64_fetch_add_unless(atomic64_t *v, s64 a, s64 u)
+{
+ s64 oldval, newval;
+ unsigned long tmp;
+
+ smp_mb();
+ prefetchw(&v->counter);
+
+ __asm__ __volatile__("@ atomic64_add_unless\n"
+"1: ldrexd %0, %H0, [%4]\n"
+" teq %0, %5\n"
+" teqeq %H0, %H5\n"
+" beq 2f\n"
+" adds %Q1, %Q0, %Q6\n"
+" adc %R1, %R0, %R6\n"
+" strexd %2, %1, %H1, [%4]\n"
+" teq %2, #0\n"
+" bne 1b\n"
+"2:"
+ : "=&r" (oldval), "=&r" (newval), "=&r" (tmp), "+Qo" (v->counter)
+ : "r" (&v->counter), "r" (u), "r" (a)
+ : "cc");
+
+ if (oldval != u)
+ smp_mb();
+
+ return oldval;
+}
+#define atomic64_fetch_add_unless atomic64_fetch_add_unless
+
+#endif /* !CONFIG_GENERIC_ATOMIC64 */
+#endif
+#endif
\ No newline at end of file
diff --git a/xen/include/asm-arm/arm32/cmpxchg.h b/xen/include/asm-arm/arm32/cmpxchg.h
new file mode 100644
index 0000000000..638ae84afb
--- /dev/null
+++ b/xen/include/asm-arm/arm32/cmpxchg.h
@@ -0,0 +1,279 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_ARM_CMPXCHG_H
+#define __ASM_ARM_CMPXCHG_H
+
+#include <linux/irqflags.h>
+#include <linux/prefetch.h>
+#include <asm/barrier.h>
+
+#if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110)
+/*
+ * On the StrongARM, "swp" is terminally broken since it bypasses the
+ * cache totally. This means that the cache becomes inconsistent, and,
+ * since we use normal loads/stores as well, this is really bad.
+ * Typically, this causes oopsen in filp_close, but could have other,
+ * more disastrous effects. There are two work-arounds:
+ * 1. Disable interrupts and emulate the atomic swap
+ * 2. Clean the cache, perform atomic swap, flush the cache
+ *
+ * We choose (1) since its the "easiest" to achieve here and is not
+ * dependent on the processor type.
+ *
+ * NOTE that this solution won't work on an SMP system, so explcitly
+ * forbid it here.
+ */
+#define swp_is_buggy
+#endif
+
+static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
+{
+ extern void __bad_xchg(volatile void *, int);
+ unsigned long ret;
+#ifdef swp_is_buggy
+ unsigned long flags;
+#endif
+#if __LINUX_ARM_ARCH__ >= 6
+ unsigned int tmp;
+#endif
+
+ prefetchw((const void *)ptr);
+
+ switch (size) {
+#if __LINUX_ARM_ARCH__ >= 6
+#ifndef CONFIG_CPU_V6 /* MIN ARCH >= V6K */
+ case 1:
+ asm volatile("@ __xchg1\n"
+ "1: ldrexb %0, [%3]\n"
+ " strexb %1, %2, [%3]\n"
+ " teq %1, #0\n"
+ " bne 1b"
+ : "=&r" (ret), "=&r" (tmp)
+ : "r" (x), "r" (ptr)
+ : "memory", "cc");
+ break;
+ case 2:
+ asm volatile("@ __xchg2\n"
+ "1: ldrexh %0, [%3]\n"
+ " strexh %1, %2, [%3]\n"
+ " teq %1, #0\n"
+ " bne 1b"
+ : "=&r" (ret), "=&r" (tmp)
+ : "r" (x), "r" (ptr)
+ : "memory", "cc");
+ break;
+#endif
+ case 4:
+ asm volatile("@ __xchg4\n"
+ "1: ldrex %0, [%3]\n"
+ " strex %1, %2, [%3]\n"
+ " teq %1, #0\n"
+ " bne 1b"
+ : "=&r" (ret), "=&r" (tmp)
+ : "r" (x), "r" (ptr)
+ : "memory", "cc");
+ break;
+#elif defined(swp_is_buggy)
+#ifdef CONFIG_SMP
+#error SMP is not supported on this platform
+#endif
+ case 1:
+ raw_local_irq_save(flags);
+ ret = *(volatile unsigned char *)ptr;
+ *(volatile unsigned char *)ptr = x;
+ raw_local_irq_restore(flags);
+ break;
+
+ case 4:
+ raw_local_irq_save(flags);
+ ret = *(volatile unsigned long *)ptr;
+ *(volatile unsigned long *)ptr = x;
+ raw_local_irq_restore(flags);
+ break;
+#else
+ case 1:
+ asm volatile("@ __xchg1\n"
+ " swpb %0, %1, [%2]"
+ : "=&r" (ret)
+ : "r" (x), "r" (ptr)
+ : "memory", "cc");
+ break;
+ case 4:
+ asm volatile("@ __xchg4\n"
+ " swp %0, %1, [%2]"
+ : "=&r" (ret)
+ : "r" (x), "r" (ptr)
+ : "memory", "cc");
+ break;
+#endif
+ default:
+ /* Cause a link-time error, the xchg() size is not supported */
+ __bad_xchg(ptr, size), ret = 0;
+ break;
+ }
+
+ return ret;
+}
+
+#define xchg_relaxed(ptr, x) ({ \
+ (__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), \
+ sizeof(*(ptr))); \
+})
+
+#include <asm-generic/cmpxchg-local.h>
+
+#if __LINUX_ARM_ARCH__ < 6
+/* min ARCH < ARMv6 */
+
+#ifdef CONFIG_SMP
+#error "SMP is not supported on this platform"
+#endif
+
+#define xchg xchg_relaxed
+
+/*
+ * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
+ * them available.
+ */
+#define cmpxchg_local(ptr, o, n) ({ \
+ (__typeof(*ptr))__cmpxchg_local_generic((ptr), \
+ (unsigned long)(o), \
+ (unsigned long)(n), \
+ sizeof(*(ptr))); \
+})
+
+#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
+
+#include <asm-generic/cmpxchg.h>
+
+#else /* min ARCH >= ARMv6 */
+
+extern void __bad_cmpxchg(volatile void *ptr, int size);
+
+/*
+ * cmpxchg only support 32-bits operands on ARMv6.
+ */
+
+static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
+ unsigned long new, int size)
+{
+ unsigned long oldval, res;
+
+ prefetchw((const void *)ptr);
+
+ switch (size) {
+#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */
+ case 1:
+ do {
+ asm volatile("@ __cmpxchg1\n"
+ " ldrexb %1, [%2]\n"
+ " mov %0, #0\n"
+ " teq %1, %3\n"
+ " strexbeq %0, %4, [%2]\n"
+ : "=&r" (res), "=&r" (oldval)
+ : "r" (ptr), "Ir" (old), "r" (new)
+ : "memory", "cc");
+ } while (res);
+ break;
+ case 2:
+ do {
+ asm volatile("@ __cmpxchg1\n"
+ " ldrexh %1, [%2]\n"
+ " mov %0, #0\n"
+ " teq %1, %3\n"
+ " strexheq %0, %4, [%2]\n"
+ : "=&r" (res), "=&r" (oldval)
+ : "r" (ptr), "Ir" (old), "r" (new)
+ : "memory", "cc");
+ } while (res);
+ break;
+#endif
+ case 4:
+ do {
+ asm volatile("@ __cmpxchg4\n"
+ " ldrex %1, [%2]\n"
+ " mov %0, #0\n"
+ " teq %1, %3\n"
+ " strexeq %0, %4, [%2]\n"
+ : "=&r" (res), "=&r" (oldval)
+ : "r" (ptr), "Ir" (old), "r" (new)
+ : "memory", "cc");
+ } while (res);
+ break;
+ default:
+ __bad_cmpxchg(ptr, size);
+ oldval = 0;
+ }
+
+ return oldval;
+}
+
+#define cmpxchg_relaxed(ptr,o,n) ({ \
+ (__typeof__(*(ptr)))__cmpxchg((ptr), \
+ (unsigned long)(o), \
+ (unsigned long)(n), \
+ sizeof(*(ptr))); \
+})
+
+static inline unsigned long __cmpxchg_local(volatile void *ptr,
+ unsigned long old,
+ unsigned long new, int size)
+{
+ unsigned long ret;
+
+ switch (size) {
+#ifdef CONFIG_CPU_V6 /* min ARCH == ARMv6 */
+ case 1:
+ case 2:
+ ret = __cmpxchg_local_generic(ptr, old, new, size);
+ break;
+#endif
+ default:
+ ret = __cmpxchg(ptr, old, new, size);
+ }
+
+ return ret;
+}
+
+#define cmpxchg_local(ptr, o, n) ({ \
+ (__typeof(*ptr))__cmpxchg_local((ptr), \
+ (unsigned long)(o), \
+ (unsigned long)(n), \
+ sizeof(*(ptr))); \
+})
+
+static inline unsigned long long __cmpxchg64(unsigned long long *ptr,
+ unsigned long long old,
+ unsigned long long new)
+{
+ unsigned long long oldval;
+ unsigned long res;
+
+ prefetchw(ptr);
+
+ __asm__ __volatile__(
+"1: ldrexd %1, %H1, [%3]\n"
+" teq %1, %4\n"
+" teqeq %H1, %H4\n"
+" bne 2f\n"
+" strexd %0, %5, %H5, [%3]\n"
+" teq %0, #0\n"
+" bne 1b\n"
+"2:"
+ : "=&r" (res), "=&r" (oldval), "+Qo" (*ptr)
+ : "r" (ptr), "r" (old), "r" (new)
+ : "cc");
+
+ return oldval;
+}
+
+#define cmpxchg64_relaxed(ptr, o, n) ({ \
+ (__typeof__(*(ptr)))__cmpxchg64((ptr), \
+ (unsigned long long)(o), \
+ (unsigned long long)(n)); \
+})
+
+#define cmpxchg64_local(ptr, o, n) cmpxchg64_relaxed((ptr), (o), (n))
+
+#endif /* __LINUX_ARM_ARCH__ >= 6 */
+
+#endif /* __ASM_ARM_CMPXCHG_H */
\ No newline at end of file
diff --git a/xen/include/asm-arm/arm64/atomic.h b/xen/include/asm-arm/arm64/atomic.h
new file mode 100644
index 0000000000..a2eab9f091
--- /dev/null
+++ b/xen/include/asm-arm/arm64/atomic.h
@@ -0,0 +1,228 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Based on arch/arm/include/asm/atomic.h
+ *
+ * Copyright (C) 1996 Russell King.
+ * Copyright (C) 2002 Deep Blue Solutions Ltd.
+ * Copyright (C) 2012 ARM Ltd.
+ */
+#ifndef __ASM_ATOMIC_H
+#define __ASM_ATOMIC_H
+
+#include <linux/compiler.h>
+#include <linux/types.h>
+
+#include <asm/barrier.h>
+#include <asm/cmpxchg.h>
+#include <asm/lse.h>
+
+#define ATOMIC_OP(op) \
+static inline void arch_##op(int i, atomic_t *v) \
+{ \
+ __lse_ll_sc_body(op, i, v); \
+}
+
+ATOMIC_OP(atomic_andnot)
+ATOMIC_OP(atomic_or)
+ATOMIC_OP(atomic_xor)
+ATOMIC_OP(atomic_add)
+ATOMIC_OP(atomic_and)
+ATOMIC_OP(atomic_sub)
+
+#undef ATOMIC_OP
+
+#define ATOMIC_FETCH_OP(name, op) \
+static inline int arch_##op##name(int i, atomic_t *v) \
+{ \
+ return __lse_ll_sc_body(op##name, i, v); \
+}
+
+#define ATOMIC_FETCH_OPS(op) \
+ ATOMIC_FETCH_OP(_relaxed, op) \
+ ATOMIC_FETCH_OP(_acquire, op) \
+ ATOMIC_FETCH_OP(_release, op) \
+ ATOMIC_FETCH_OP( , op)
+
+ATOMIC_FETCH_OPS(atomic_fetch_andnot)
+ATOMIC_FETCH_OPS(atomic_fetch_or)
+ATOMIC_FETCH_OPS(atomic_fetch_xor)
+ATOMIC_FETCH_OPS(atomic_fetch_add)
+ATOMIC_FETCH_OPS(atomic_fetch_and)
+ATOMIC_FETCH_OPS(atomic_fetch_sub)
+ATOMIC_FETCH_OPS(atomic_add_return)
+ATOMIC_FETCH_OPS(atomic_sub_return)
+
+#undef ATOMIC_FETCH_OP
+#undef ATOMIC_FETCH_OPS
+
+#define ATOMIC64_OP(op) \
+static inline void arch_##op(long i, atomic64_t *v) \
+{ \
+ __lse_ll_sc_body(op, i, v); \
+}
+
+ATOMIC64_OP(atomic64_andnot)
+ATOMIC64_OP(atomic64_or)
+ATOMIC64_OP(atomic64_xor)
+ATOMIC64_OP(atomic64_add)
+ATOMIC64_OP(atomic64_and)
+ATOMIC64_OP(atomic64_sub)
+
+#undef ATOMIC64_OP
+
+#define ATOMIC64_FETCH_OP(name, op) \
+static inline long arch_##op##name(long i, atomic64_t *v) \
+{ \
+ return __lse_ll_sc_body(op##name, i, v); \
+}
+
+#define ATOMIC64_FETCH_OPS(op) \
+ ATOMIC64_FETCH_OP(_relaxed, op) \
+ ATOMIC64_FETCH_OP(_acquire, op) \
+ ATOMIC64_FETCH_OP(_release, op) \
+ ATOMIC64_FETCH_OP( , op)
+
+ATOMIC64_FETCH_OPS(atomic64_fetch_andnot)
+ATOMIC64_FETCH_OPS(atomic64_fetch_or)
+ATOMIC64_FETCH_OPS(atomic64_fetch_xor)
+ATOMIC64_FETCH_OPS(atomic64_fetch_add)
+ATOMIC64_FETCH_OPS(atomic64_fetch_and)
+ATOMIC64_FETCH_OPS(atomic64_fetch_sub)
+ATOMIC64_FETCH_OPS(atomic64_add_return)
+ATOMIC64_FETCH_OPS(atomic64_sub_return)
+
+#undef ATOMIC64_FETCH_OP
+#undef ATOMIC64_FETCH_OPS
+
+static inline long arch_atomic64_dec_if_positive(atomic64_t *v)
+{
+ return __lse_ll_sc_body(atomic64_dec_if_positive, v);
+}
+
+#define arch_atomic_read(v) __READ_ONCE((v)->counter)
+#define arch_atomic_set(v, i) __WRITE_ONCE(((v)->counter), (i))
+
+#define arch_atomic_add_return_relaxed arch_atomic_add_return_relaxed
+#define arch_atomic_add_return_acquire arch_atomic_add_return_acquire
+#define arch_atomic_add_return_release arch_atomic_add_return_release
+#define arch_atomic_add_return arch_atomic_add_return
+
+#define arch_atomic_sub_return_relaxed arch_atomic_sub_return_relaxed
+#define arch_atomic_sub_return_acquire arch_atomic_sub_return_acquire
+#define arch_atomic_sub_return_release arch_atomic_sub_return_release
+#define arch_atomic_sub_return arch_atomic_sub_return
+
+#define arch_atomic_fetch_add_relaxed arch_atomic_fetch_add_relaxed
+#define arch_atomic_fetch_add_acquire arch_atomic_fetch_add_acquire
+#define arch_atomic_fetch_add_release arch_atomic_fetch_add_release
+#define arch_atomic_fetch_add arch_atomic_fetch_add
+
+#define arch_atomic_fetch_sub_relaxed arch_atomic_fetch_sub_relaxed
+#define arch_atomic_fetch_sub_acquire arch_atomic_fetch_sub_acquire
+#define arch_atomic_fetch_sub_release arch_atomic_fetch_sub_release
+#define arch_atomic_fetch_sub arch_atomic_fetch_sub
+
+#define arch_atomic_fetch_and_relaxed arch_atomic_fetch_and_relaxed
+#define arch_atomic_fetch_and_acquire arch_atomic_fetch_and_acquire
+#define arch_atomic_fetch_and_release arch_atomic_fetch_and_release
+#define arch_atomic_fetch_and arch_atomic_fetch_and
+
+#define arch_atomic_fetch_andnot_relaxed arch_atomic_fetch_andnot_relaxed
+#define arch_atomic_fetch_andnot_acquire arch_atomic_fetch_andnot_acquire
+#define arch_atomic_fetch_andnot_release arch_atomic_fetch_andnot_release
+#define arch_atomic_fetch_andnot arch_atomic_fetch_andnot
+
+#define arch_atomic_fetch_or_relaxed arch_atomic_fetch_or_relaxed
+#define arch_atomic_fetch_or_acquire arch_atomic_fetch_or_acquire
+#define arch_atomic_fetch_or_release arch_atomic_fetch_or_release
+#define arch_atomic_fetch_or arch_atomic_fetch_or
+
+#define arch_atomic_fetch_xor_relaxed arch_atomic_fetch_xor_relaxed
+#define arch_atomic_fetch_xor_acquire arch_atomic_fetch_xor_acquire
+#define arch_atomic_fetch_xor_release arch_atomic_fetch_xor_release
+#define arch_atomic_fetch_xor arch_atomic_fetch_xor
+
+#define arch_atomic_xchg_relaxed(v, new) \
+ arch_xchg_relaxed(&((v)->counter), (new))
+#define arch_atomic_xchg_acquire(v, new) \
+ arch_xchg_acquire(&((v)->counter), (new))
+#define arch_atomic_xchg_release(v, new) \
+ arch_xchg_release(&((v)->counter), (new))
+#define arch_atomic_xchg(v, new) \
+ arch_xchg(&((v)->counter), (new))
+
+#define arch_atomic_cmpxchg_relaxed(v, old, new) \
+ arch_cmpxchg_relaxed(&((v)->counter), (old), (new))
+#define arch_atomic_cmpxchg_acquire(v, old, new) \
+ arch_cmpxchg_acquire(&((v)->counter), (old), (new))
+#define arch_atomic_cmpxchg_release(v, old, new) \
+ arch_cmpxchg_release(&((v)->counter), (old), (new))
+#define arch_atomic_cmpxchg(v, old, new) \
+ arch_cmpxchg(&((v)->counter), (old), (new))
+
+#define arch_atomic_andnot arch_atomic_andnot
+
+/*
+ * 64-bit arch_atomic operations.
+ */
+#define ATOMIC64_INIT ATOMIC_INIT
+#define arch_atomic64_read arch_atomic_read
+#define arch_atomic64_set arch_atomic_set
+
+#define arch_atomic64_add_return_relaxed arch_atomic64_add_return_relaxed
+#define arch_atomic64_add_return_acquire arch_atomic64_add_return_acquire
+#define arch_atomic64_add_return_release arch_atomic64_add_return_release
+#define arch_atomic64_add_return arch_atomic64_add_return
+
+#define arch_atomic64_sub_return_relaxed arch_atomic64_sub_return_relaxed
+#define arch_atomic64_sub_return_acquire arch_atomic64_sub_return_acquire
+#define arch_atomic64_sub_return_release arch_atomic64_sub_return_release
+#define arch_atomic64_sub_return arch_atomic64_sub_return
+
+#define arch_atomic64_fetch_add_relaxed arch_atomic64_fetch_add_relaxed
+#define arch_atomic64_fetch_add_acquire arch_atomic64_fetch_add_acquire
+#define arch_atomic64_fetch_add_release arch_atomic64_fetch_add_release
+#define arch_atomic64_fetch_add arch_atomic64_fetch_add
+
+#define arch_atomic64_fetch_sub_relaxed arch_atomic64_fetch_sub_relaxed
+#define arch_atomic64_fetch_sub_acquire arch_atomic64_fetch_sub_acquire
+#define arch_atomic64_fetch_sub_release arch_atomic64_fetch_sub_release
+#define arch_atomic64_fetch_sub arch_atomic64_fetch_sub
+
+#define arch_atomic64_fetch_and_relaxed arch_atomic64_fetch_and_relaxed
+#define arch_atomic64_fetch_and_acquire arch_atomic64_fetch_and_acquire
+#define arch_atomic64_fetch_and_release arch_atomic64_fetch_and_release
+#define arch_atomic64_fetch_and arch_atomic64_fetch_and
+
+#define arch_atomic64_fetch_andnot_relaxed arch_atomic64_fetch_andnot_relaxed
+#define arch_atomic64_fetch_andnot_acquire arch_atomic64_fetch_andnot_acquire
+#define arch_atomic64_fetch_andnot_release arch_atomic64_fetch_andnot_release
+#define arch_atomic64_fetch_andnot arch_atomic64_fetch_andnot
+
+#define arch_atomic64_fetch_or_relaxed arch_atomic64_fetch_or_relaxed
+#define arch_atomic64_fetch_or_acquire arch_atomic64_fetch_or_acquire
+#define arch_atomic64_fetch_or_release arch_atomic64_fetch_or_release
+#define arch_atomic64_fetch_or arch_atomic64_fetch_or
+
+#define arch_atomic64_fetch_xor_relaxed arch_atomic64_fetch_xor_relaxed
+#define arch_atomic64_fetch_xor_acquire arch_atomic64_fetch_xor_acquire
+#define arch_atomic64_fetch_xor_release arch_atomic64_fetch_xor_release
+#define arch_atomic64_fetch_xor arch_atomic64_fetch_xor
+
+#define arch_atomic64_xchg_relaxed arch_atomic_xchg_relaxed
+#define arch_atomic64_xchg_acquire arch_atomic_xchg_acquire
+#define arch_atomic64_xchg_release arch_atomic_xchg_release
+#define arch_atomic64_xchg arch_atomic_xchg
+
+#define arch_atomic64_cmpxchg_relaxed arch_atomic_cmpxchg_relaxed
+#define arch_atomic64_cmpxchg_acquire arch_atomic_cmpxchg_acquire
+#define arch_atomic64_cmpxchg_release arch_atomic_cmpxchg_release
+#define arch_atomic64_cmpxchg arch_atomic_cmpxchg
+
+#define arch_atomic64_andnot arch_atomic64_andnot
+
+#define arch_atomic64_dec_if_positive arch_atomic64_dec_if_positive
+
+#define ARCH_ATOMIC
+
+#endif /* __ASM_ATOMIC_H */
\ No newline at end of file
diff --git a/xen/include/asm-arm/arm64/atomic_ll_sc.h b/xen/include/asm-arm/arm64/atomic_ll_sc.h
new file mode 100644
index 0000000000..e1009c0f94
--- /dev/null
+++ b/xen/include/asm-arm/arm64/atomic_ll_sc.h
@@ -0,0 +1,353 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Based on arch/arm/include/asm/atomic.h
+ *
+ * Copyright (C) 1996 Russell King.
+ * Copyright (C) 2002 Deep Blue Solutions Ltd.
+ * Copyright (C) 2012 ARM Ltd.
+ */
+
+#ifndef __ASM_ATOMIC_LL_SC_H
+#define __ASM_ATOMIC_LL_SC_H
+
+#include <linux/stringify.h>
+
+#ifdef CONFIG_ARM64_LSE_ATOMICS
+#define __LL_SC_FALLBACK(asm_ops) \
+" b 3f\n" \
+" .subsection 1\n" \
+"3:\n" \
+asm_ops "\n" \
+" b 4f\n" \
+" .previous\n" \
+"4:\n"
+#else
+#define __LL_SC_FALLBACK(asm_ops) asm_ops
+#endif
+
+#ifndef CONFIG_CC_HAS_K_CONSTRAINT
+#define K
+#endif
+
+/*
+ * AArch64 UP and SMP safe atomic ops. We use load exclusive and
+ * store exclusive to ensure that these are atomic. We may loop
+ * to ensure that the update happens.
+ */
+
+#define ATOMIC_OP(op, asm_op, constraint) \
+static inline void \
+__ll_sc_atomic_##op(int i, atomic_t *v) \
+{ \
+ unsigned long tmp; \
+ int result; \
+ \
+ asm volatile("// atomic_" #op "\n" \
+ __LL_SC_FALLBACK( \
+" prfm pstl1strm, %2\n" \
+"1: ldxr %w0, %2\n" \
+" " #asm_op " %w0, %w0, %w3\n" \
+" stxr %w1, %w0, %2\n" \
+" cbnz %w1, 1b\n") \
+ : "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
+ : __stringify(constraint) "r" (i)); \
+}
+
+#define ATOMIC_OP_RETURN(name, mb, acq, rel, cl, op, asm_op, constraint)\
+static inline int \
+__ll_sc_atomic_##op##_return##name(int i, atomic_t *v) \
+{ \
+ unsigned long tmp; \
+ int result; \
+ \
+ asm volatile("// atomic_" #op "_return" #name "\n" \
+ __LL_SC_FALLBACK( \
+" prfm pstl1strm, %2\n" \
+"1: ld" #acq "xr %w0, %2\n" \
+" " #asm_op " %w0, %w0, %w3\n" \
+" st" #rel "xr %w1, %w0, %2\n" \
+" cbnz %w1, 1b\n" \
+" " #mb ) \
+ : "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
+ : __stringify(constraint) "r" (i) \
+ : cl); \
+ \
+ return result; \
+}
+
+#define ATOMIC_FETCH_OP(name, mb, acq, rel, cl, op, asm_op, constraint) \
+static inline int \
+__ll_sc_atomic_fetch_##op##name(int i, atomic_t *v) \
+{ \
+ unsigned long tmp; \
+ int val, result; \
+ \
+ asm volatile("// atomic_fetch_" #op #name "\n" \
+ __LL_SC_FALLBACK( \
+" prfm pstl1strm, %3\n" \
+"1: ld" #acq "xr %w0, %3\n" \
+" " #asm_op " %w1, %w0, %w4\n" \
+" st" #rel "xr %w2, %w1, %3\n" \
+" cbnz %w2, 1b\n" \
+" " #mb ) \
+ : "=&r" (result), "=&r" (val), "=&r" (tmp), "+Q" (v->counter) \
+ : __stringify(constraint) "r" (i) \
+ : cl); \
+ \
+ return result; \
+}
+
+#define ATOMIC_OPS(...) \
+ ATOMIC_OP(__VA_ARGS__) \
+ ATOMIC_OP_RETURN( , dmb ish, , l, "memory", __VA_ARGS__)\
+ ATOMIC_OP_RETURN(_relaxed, , , , , __VA_ARGS__)\
+ ATOMIC_OP_RETURN(_acquire, , a, , "memory", __VA_ARGS__)\
+ ATOMIC_OP_RETURN(_release, , , l, "memory", __VA_ARGS__)\
+ ATOMIC_FETCH_OP ( , dmb ish, , l, "memory", __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_relaxed, , , , , __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_acquire, , a, , "memory", __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_release, , , l, "memory", __VA_ARGS__)
+
+ATOMIC_OPS(add, add, I)
+ATOMIC_OPS(sub, sub, J)
+
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(...) \
+ ATOMIC_OP(__VA_ARGS__) \
+ ATOMIC_FETCH_OP ( , dmb ish, , l, "memory", __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_relaxed, , , , , __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_acquire, , a, , "memory", __VA_ARGS__)\
+ ATOMIC_FETCH_OP (_release, , , l, "memory", __VA_ARGS__)
+
+ATOMIC_OPS(and, and, K)
+ATOMIC_OPS(or, orr, K)
+ATOMIC_OPS(xor, eor, K)
+/*
+ * GAS converts the mysterious and undocumented BIC (immediate) alias to
+ * an AND (immediate) instruction with the immediate inverted. We don't
+ * have a constraint for this, so fall back to register.
+ */
+ATOMIC_OPS(andnot, bic, )
+
+#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
+#undef ATOMIC_OP_RETURN
+#undef ATOMIC_OP
+
+#define ATOMIC64_OP(op, asm_op, constraint) \
+static inline void \
+__ll_sc_atomic64_##op(s64 i, atomic64_t *v) \
+{ \
+ s64 result; \
+ unsigned long tmp; \
+ \
+ asm volatile("// atomic64_" #op "\n" \
+ __LL_SC_FALLBACK( \
+" prfm pstl1strm, %2\n" \
+"1: ldxr %0, %2\n" \
+" " #asm_op " %0, %0, %3\n" \
+" stxr %w1, %0, %2\n" \
+" cbnz %w1, 1b") \
+ : "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
+ : __stringify(constraint) "r" (i)); \
+}
+
+#define ATOMIC64_OP_RETURN(name, mb, acq, rel, cl, op, asm_op, constraint)\
+static inline long \
+__ll_sc_atomic64_##op##_return##name(s64 i, atomic64_t *v) \
+{ \
+ s64 result; \
+ unsigned long tmp; \
+ \
+ asm volatile("// atomic64_" #op "_return" #name "\n" \
+ __LL_SC_FALLBACK( \
+" prfm pstl1strm, %2\n" \
+"1: ld" #acq "xr %0, %2\n" \
+" " #asm_op " %0, %0, %3\n" \
+" st" #rel "xr %w1, %0, %2\n" \
+" cbnz %w1, 1b\n" \
+" " #mb ) \
+ : "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
+ : __stringify(constraint) "r" (i) \
+ : cl); \
+ \
+ return result; \
+}
+
+#define ATOMIC64_FETCH_OP(name, mb, acq, rel, cl, op, asm_op, constraint)\
+static inline long \
+__ll_sc_atomic64_fetch_##op##name(s64 i, atomic64_t *v) \
+{ \
+ s64 result, val; \
+ unsigned long tmp; \
+ \
+ asm volatile("// atomic64_fetch_" #op #name "\n" \
+ __LL_SC_FALLBACK( \
+" prfm pstl1strm, %3\n" \
+"1: ld" #acq "xr %0, %3\n" \
+" " #asm_op " %1, %0, %4\n" \
+" st" #rel "xr %w2, %1, %3\n" \
+" cbnz %w2, 1b\n" \
+" " #mb ) \
+ : "=&r" (result), "=&r" (val), "=&r" (tmp), "+Q" (v->counter) \
+ : __stringify(constraint) "r" (i) \
+ : cl); \
+ \
+ return result; \
+}
+
+#define ATOMIC64_OPS(...) \
+ ATOMIC64_OP(__VA_ARGS__) \
+ ATOMIC64_OP_RETURN(, dmb ish, , l, "memory", __VA_ARGS__) \
+ ATOMIC64_OP_RETURN(_relaxed,, , , , __VA_ARGS__) \
+ ATOMIC64_OP_RETURN(_acquire,, a, , "memory", __VA_ARGS__) \
+ ATOMIC64_OP_RETURN(_release,, , l, "memory", __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (, dmb ish, , l, "memory", __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_relaxed,, , , , __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_acquire,, a, , "memory", __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_release,, , l, "memory", __VA_ARGS__)
+
+ATOMIC64_OPS(add, add, I)
+ATOMIC64_OPS(sub, sub, J)
+
+#undef ATOMIC64_OPS
+#define ATOMIC64_OPS(...) \
+ ATOMIC64_OP(__VA_ARGS__) \
+ ATOMIC64_FETCH_OP (, dmb ish, , l, "memory", __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_relaxed,, , , , __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_acquire,, a, , "memory", __VA_ARGS__) \
+ ATOMIC64_FETCH_OP (_release,, , l, "memory", __VA_ARGS__)
+
+ATOMIC64_OPS(and, and, L)
+ATOMIC64_OPS(or, orr, L)
+ATOMIC64_OPS(xor, eor, L)
+/*
+ * GAS converts the mysterious and undocumented BIC (immediate) alias to
+ * an AND (immediate) instruction with the immediate inverted. We don't
+ * have a constraint for this, so fall back to register.
+ */
+ATOMIC64_OPS(andnot, bic, )
+
+#undef ATOMIC64_OPS
+#undef ATOMIC64_FETCH_OP
+#undef ATOMIC64_OP_RETURN
+#undef ATOMIC64_OP
+
+static inline s64
+__ll_sc_atomic64_dec_if_positive(atomic64_t *v)
+{
+ s64 result;
+ unsigned long tmp;
+
+ asm volatile("// atomic64_dec_if_positive\n"
+ __LL_SC_FALLBACK(
+" prfm pstl1strm, %2\n"
+"1: ldxr %0, %2\n"
+" subs %0, %0, #1\n"
+" b.lt 2f\n"
+" stlxr %w1, %0, %2\n"
+" cbnz %w1, 1b\n"
+" dmb ish\n"
+"2:")
+ : "=&r" (result), "=&r" (tmp), "+Q" (v->counter)
+ :
+ : "cc", "memory");
+
+ return result;
+}
+
+#define __CMPXCHG_CASE(w, sfx, name, sz, mb, acq, rel, cl, constraint) \
+static inline u##sz \
+__ll_sc__cmpxchg_case_##name##sz(volatile void *ptr, \
+ unsigned long old, \
+ u##sz new) \
+{ \
+ unsigned long tmp; \
+ u##sz oldval; \
+ \
+ /* \
+ * Sub-word sizes require explicit casting so that the compare \
+ * part of the cmpxchg doesn't end up interpreting non-zero \
+ * upper bits of the register containing "old". \
+ */ \
+ if (sz < 32) \
+ old = (u##sz)old; \
+ \
+ asm volatile( \
+ __LL_SC_FALLBACK( \
+ " prfm pstl1strm, %[v]\n" \
+ "1: ld" #acq "xr" #sfx "\t%" #w "[oldval], %[v]\n" \
+ " eor %" #w "[tmp], %" #w "[oldval], %" #w "[old]\n" \
+ " cbnz %" #w "[tmp], 2f\n" \
+ " st" #rel "xr" #sfx "\t%w[tmp], %" #w "[new], %[v]\n" \
+ " cbnz %w[tmp], 1b\n" \
+ " " #mb "\n" \
+ "2:") \
+ : [tmp] "=&r" (tmp), [oldval] "=&r" (oldval), \
+ [v] "+Q" (*(u##sz *)ptr) \
+ : [old] __stringify(constraint) "r" (old), [new] "r" (new) \
+ : cl); \
+ \
+ return oldval; \
+}
+
+/*
+ * Earlier versions of GCC (no later than 8.1.0) appear to incorrectly
+ * handle the 'K' constraint for the value 4294967295 - thus we use no
+ * constraint for 32 bit operations.
+ */
+__CMPXCHG_CASE(w, b, , 8, , , , , K)
+__CMPXCHG_CASE(w, h, , 16, , , , , K)
+__CMPXCHG_CASE(w, , , 32, , , , , K)
+__CMPXCHG_CASE( , , , 64, , , , , L)
+__CMPXCHG_CASE(w, b, acq_, 8, , a, , "memory", K)
+__CMPXCHG_CASE(w, h, acq_, 16, , a, , "memory", K)
+__CMPXCHG_CASE(w, , acq_, 32, , a, , "memory", K)
+__CMPXCHG_CASE( , , acq_, 64, , a, , "memory", L)
+__CMPXCHG_CASE(w, b, rel_, 8, , , l, "memory", K)
+__CMPXCHG_CASE(w, h, rel_, 16, , , l, "memory", K)
+__CMPXCHG_CASE(w, , rel_, 32, , , l, "memory", K)
+__CMPXCHG_CASE( , , rel_, 64, , , l, "memory", L)
+__CMPXCHG_CASE(w, b, mb_, 8, dmb ish, , l, "memory", K)
+__CMPXCHG_CASE(w, h, mb_, 16, dmb ish, , l, "memory", K)
+__CMPXCHG_CASE(w, , mb_, 32, dmb ish, , l, "memory", K)
+__CMPXCHG_CASE( , , mb_, 64, dmb ish, , l, "memory", L)
+
+#undef __CMPXCHG_CASE
+
+#define __CMPXCHG_DBL(name, mb, rel, cl) \
+static inline long \
+__ll_sc__cmpxchg_double##name(unsigned long old1, \
+ unsigned long old2, \
+ unsigned long new1, \
+ unsigned long new2, \
+ volatile void *ptr) \
+{ \
+ unsigned long tmp, ret; \
+ \
+ asm volatile("// __cmpxchg_double" #name "\n" \
+ __LL_SC_FALLBACK( \
+ " prfm pstl1strm, %2\n" \
+ "1: ldxp %0, %1, %2\n" \
+ " eor %0, %0, %3\n" \
+ " eor %1, %1, %4\n" \
+ " orr %1, %0, %1\n" \
+ " cbnz %1, 2f\n" \
+ " st" #rel "xp %w0, %5, %6, %2\n" \
+ " cbnz %w0, 1b\n" \
+ " " #mb "\n" \
+ "2:") \
+ : "=&r" (tmp), "=&r" (ret), "+Q" (*(unsigned long *)ptr) \
+ : "r" (old1), "r" (old2), "r" (new1), "r" (new2) \
+ : cl); \
+ \
+ return ret; \
+}
+
+__CMPXCHG_DBL( , , , )
+__CMPXCHG_DBL(_mb, dmb ish, l, "memory")
+
+#undef __CMPXCHG_DBL
+#undef K
+
+#endif /* __ASM_ATOMIC_LL_SC_H */
\ No newline at end of file
diff --git a/xen/include/asm-arm/arm64/atomic_lse.h b/xen/include/asm-arm/arm64/atomic_lse.h
new file mode 100644
index 0000000000..b3b0d43a7d
--- /dev/null
+++ b/xen/include/asm-arm/arm64/atomic_lse.h
@@ -0,0 +1,419 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Based on arch/arm/include/asm/atomic.h
+ *
+ * Copyright (C) 1996 Russell King.
+ * Copyright (C) 2002 Deep Blue Solutions Ltd.
+ * Copyright (C) 2012 ARM Ltd.
+ */
+
+#ifndef __ASM_ATOMIC_LSE_H
+#define __ASM_ATOMIC_LSE_H
+
+#define ATOMIC_OP(op, asm_op) \
+static inline void __lse_atomic_##op(int i, atomic_t *v) \
+{ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+" " #asm_op " %w[i], %[v]\n" \
+ : [i] "+r" (i), [v] "+Q" (v->counter) \
+ : "r" (v)); \
+}
+
+ATOMIC_OP(andnot, stclr)
+ATOMIC_OP(or, stset)
+ATOMIC_OP(xor, steor)
+ATOMIC_OP(add, stadd)
+
+#undef ATOMIC_OP
+
+#define ATOMIC_FETCH_OP(name, mb, op, asm_op, cl...) \
+static inline int __lse_atomic_fetch_##op##name(int i, atomic_t *v) \
+{ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+" " #asm_op #mb " %w[i], %w[i], %[v]" \
+ : [i] "+r" (i), [v] "+Q" (v->counter) \
+ : "r" (v) \
+ : cl); \
+ \
+ return i; \
+}
+
+#define ATOMIC_FETCH_OPS(op, asm_op) \
+ ATOMIC_FETCH_OP(_relaxed, , op, asm_op) \
+ ATOMIC_FETCH_OP(_acquire, a, op, asm_op, "memory") \
+ ATOMIC_FETCH_OP(_release, l, op, asm_op, "memory") \
+ ATOMIC_FETCH_OP( , al, op, asm_op, "memory")
+
+ATOMIC_FETCH_OPS(andnot, ldclr)
+ATOMIC_FETCH_OPS(or, ldset)
+ATOMIC_FETCH_OPS(xor, ldeor)
+ATOMIC_FETCH_OPS(add, ldadd)
+
+#undef ATOMIC_FETCH_OP
+#undef ATOMIC_FETCH_OPS
+
+#define ATOMIC_OP_ADD_RETURN(name, mb, cl...) \
+static inline int __lse_atomic_add_return##name(int i, atomic_t *v) \
+{ \
+ u32 tmp; \
+ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " ldadd" #mb " %w[i], %w[tmp], %[v]\n" \
+ " add %w[i], %w[i], %w[tmp]" \
+ : [i] "+r" (i), [v] "+Q" (v->counter), [tmp] "=&r" (tmp) \
+ : "r" (v) \
+ : cl); \
+ \
+ return i; \
+}
+
+ATOMIC_OP_ADD_RETURN(_relaxed, )
+ATOMIC_OP_ADD_RETURN(_acquire, a, "memory")
+ATOMIC_OP_ADD_RETURN(_release, l, "memory")
+ATOMIC_OP_ADD_RETURN( , al, "memory")
+
+#undef ATOMIC_OP_ADD_RETURN
+
+static inline void __lse_atomic_and(int i, atomic_t *v)
+{
+ asm volatile(
+ __LSE_PREAMBLE
+ " mvn %w[i], %w[i]\n"
+ " stclr %w[i], %[v]"
+ : [i] "+&r" (i), [v] "+Q" (v->counter)
+ : "r" (v));
+}
+
+#define ATOMIC_FETCH_OP_AND(name, mb, cl...) \
+static inline int __lse_atomic_fetch_and##name(int i, atomic_t *v) \
+{ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " mvn %w[i], %w[i]\n" \
+ " ldclr" #mb " %w[i], %w[i], %[v]" \
+ : [i] "+&r" (i), [v] "+Q" (v->counter) \
+ : "r" (v) \
+ : cl); \
+ \
+ return i; \
+}
+
+ATOMIC_FETCH_OP_AND(_relaxed, )
+ATOMIC_FETCH_OP_AND(_acquire, a, "memory")
+ATOMIC_FETCH_OP_AND(_release, l, "memory")
+ATOMIC_FETCH_OP_AND( , al, "memory")
+
+#undef ATOMIC_FETCH_OP_AND
+
+static inline void __lse_atomic_sub(int i, atomic_t *v)
+{
+ asm volatile(
+ __LSE_PREAMBLE
+ " neg %w[i], %w[i]\n"
+ " stadd %w[i], %[v]"
+ : [i] "+&r" (i), [v] "+Q" (v->counter)
+ : "r" (v));
+}
+
+#define ATOMIC_OP_SUB_RETURN(name, mb, cl...) \
+static inline int __lse_atomic_sub_return##name(int i, atomic_t *v) \
+{ \
+ u32 tmp; \
+ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " neg %w[i], %w[i]\n" \
+ " ldadd" #mb " %w[i], %w[tmp], %[v]\n" \
+ " add %w[i], %w[i], %w[tmp]" \
+ : [i] "+&r" (i), [v] "+Q" (v->counter), [tmp] "=&r" (tmp) \
+ : "r" (v) \
+ : cl); \
+ \
+ return i; \
+}
+
+ATOMIC_OP_SUB_RETURN(_relaxed, )
+ATOMIC_OP_SUB_RETURN(_acquire, a, "memory")
+ATOMIC_OP_SUB_RETURN(_release, l, "memory")
+ATOMIC_OP_SUB_RETURN( , al, "memory")
+
+#undef ATOMIC_OP_SUB_RETURN
+
+#define ATOMIC_FETCH_OP_SUB(name, mb, cl...) \
+static inline int __lse_atomic_fetch_sub##name(int i, atomic_t *v) \
+{ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " neg %w[i], %w[i]\n" \
+ " ldadd" #mb " %w[i], %w[i], %[v]" \
+ : [i] "+&r" (i), [v] "+Q" (v->counter) \
+ : "r" (v) \
+ : cl); \
+ \
+ return i; \
+}
+
+ATOMIC_FETCH_OP_SUB(_relaxed, )
+ATOMIC_FETCH_OP_SUB(_acquire, a, "memory")
+ATOMIC_FETCH_OP_SUB(_release, l, "memory")
+ATOMIC_FETCH_OP_SUB( , al, "memory")
+
+#undef ATOMIC_FETCH_OP_SUB
+
+#define ATOMIC64_OP(op, asm_op) \
+static inline void __lse_atomic64_##op(s64 i, atomic64_t *v) \
+{ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+" " #asm_op " %[i], %[v]\n" \
+ : [i] "+r" (i), [v] "+Q" (v->counter) \
+ : "r" (v)); \
+}
+
+ATOMIC64_OP(andnot, stclr)
+ATOMIC64_OP(or, stset)
+ATOMIC64_OP(xor, steor)
+ATOMIC64_OP(add, stadd)
+
+#undef ATOMIC64_OP
+
+#define ATOMIC64_FETCH_OP(name, mb, op, asm_op, cl...) \
+static inline long __lse_atomic64_fetch_##op##name(s64 i, atomic64_t *v)\
+{ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+" " #asm_op #mb " %[i], %[i], %[v]" \
+ : [i] "+r" (i), [v] "+Q" (v->counter) \
+ : "r" (v) \
+ : cl); \
+ \
+ return i; \
+}
+
+#define ATOMIC64_FETCH_OPS(op, asm_op) \
+ ATOMIC64_FETCH_OP(_relaxed, , op, asm_op) \
+ ATOMIC64_FETCH_OP(_acquire, a, op, asm_op, "memory") \
+ ATOMIC64_FETCH_OP(_release, l, op, asm_op, "memory") \
+ ATOMIC64_FETCH_OP( , al, op, asm_op, "memory")
+
+ATOMIC64_FETCH_OPS(andnot, ldclr)
+ATOMIC64_FETCH_OPS(or, ldset)
+ATOMIC64_FETCH_OPS(xor, ldeor)
+ATOMIC64_FETCH_OPS(add, ldadd)
+
+#undef ATOMIC64_FETCH_OP
+#undef ATOMIC64_FETCH_OPS
+
+#define ATOMIC64_OP_ADD_RETURN(name, mb, cl...) \
+static inline long __lse_atomic64_add_return##name(s64 i, atomic64_t *v)\
+{ \
+ unsigned long tmp; \
+ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " ldadd" #mb " %[i], %x[tmp], %[v]\n" \
+ " add %[i], %[i], %x[tmp]" \
+ : [i] "+r" (i), [v] "+Q" (v->counter), [tmp] "=&r" (tmp) \
+ : "r" (v) \
+ : cl); \
+ \
+ return i; \
+}
+
+ATOMIC64_OP_ADD_RETURN(_relaxed, )
+ATOMIC64_OP_ADD_RETURN(_acquire, a, "memory")
+ATOMIC64_OP_ADD_RETURN(_release, l, "memory")
+ATOMIC64_OP_ADD_RETURN( , al, "memory")
+
+#undef ATOMIC64_OP_ADD_RETURN
+
+static inline void __lse_atomic64_and(s64 i, atomic64_t *v)
+{
+ asm volatile(
+ __LSE_PREAMBLE
+ " mvn %[i], %[i]\n"
+ " stclr %[i], %[v]"
+ : [i] "+&r" (i), [v] "+Q" (v->counter)
+ : "r" (v));
+}
+
+#define ATOMIC64_FETCH_OP_AND(name, mb, cl...) \
+static inline long __lse_atomic64_fetch_and##name(s64 i, atomic64_t *v) \
+{ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " mvn %[i], %[i]\n" \
+ " ldclr" #mb " %[i], %[i], %[v]" \
+ : [i] "+&r" (i), [v] "+Q" (v->counter) \
+ : "r" (v) \
+ : cl); \
+ \
+ return i; \
+}
+
+ATOMIC64_FETCH_OP_AND(_relaxed, )
+ATOMIC64_FETCH_OP_AND(_acquire, a, "memory")
+ATOMIC64_FETCH_OP_AND(_release, l, "memory")
+ATOMIC64_FETCH_OP_AND( , al, "memory")
+
+#undef ATOMIC64_FETCH_OP_AND
+
+static inline void __lse_atomic64_sub(s64 i, atomic64_t *v)
+{
+ asm volatile(
+ __LSE_PREAMBLE
+ " neg %[i], %[i]\n"
+ " stadd %[i], %[v]"
+ : [i] "+&r" (i), [v] "+Q" (v->counter)
+ : "r" (v));
+}
+
+#define ATOMIC64_OP_SUB_RETURN(name, mb, cl...) \
+static inline long __lse_atomic64_sub_return##name(s64 i, atomic64_t *v) \
+{ \
+ unsigned long tmp; \
+ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " neg %[i], %[i]\n" \
+ " ldadd" #mb " %[i], %x[tmp], %[v]\n" \
+ " add %[i], %[i], %x[tmp]" \
+ : [i] "+&r" (i), [v] "+Q" (v->counter), [tmp] "=&r" (tmp) \
+ : "r" (v) \
+ : cl); \
+ \
+ return i; \
+}
+
+ATOMIC64_OP_SUB_RETURN(_relaxed, )
+ATOMIC64_OP_SUB_RETURN(_acquire, a, "memory")
+ATOMIC64_OP_SUB_RETURN(_release, l, "memory")
+ATOMIC64_OP_SUB_RETURN( , al, "memory")
+
+#undef ATOMIC64_OP_SUB_RETURN
+
+#define ATOMIC64_FETCH_OP_SUB(name, mb, cl...) \
+static inline long __lse_atomic64_fetch_sub##name(s64 i, atomic64_t *v) \
+{ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " neg %[i], %[i]\n" \
+ " ldadd" #mb " %[i], %[i], %[v]" \
+ : [i] "+&r" (i), [v] "+Q" (v->counter) \
+ : "r" (v) \
+ : cl); \
+ \
+ return i; \
+}
+
+ATOMIC64_FETCH_OP_SUB(_relaxed, )
+ATOMIC64_FETCH_OP_SUB(_acquire, a, "memory")
+ATOMIC64_FETCH_OP_SUB(_release, l, "memory")
+ATOMIC64_FETCH_OP_SUB( , al, "memory")
+
+#undef ATOMIC64_FETCH_OP_SUB
+
+static inline s64 __lse_atomic64_dec_if_positive(atomic64_t *v)
+{
+ unsigned long tmp;
+
+ asm volatile(
+ __LSE_PREAMBLE
+ "1: ldr %x[tmp], %[v]\n"
+ " subs %[ret], %x[tmp], #1\n"
+ " b.lt 2f\n"
+ " casal %x[tmp], %[ret], %[v]\n"
+ " sub %x[tmp], %x[tmp], #1\n"
+ " sub %x[tmp], %x[tmp], %[ret]\n"
+ " cbnz %x[tmp], 1b\n"
+ "2:"
+ : [ret] "+&r" (v), [v] "+Q" (v->counter), [tmp] "=&r" (tmp)
+ :
+ : "cc", "memory");
+
+ return (long)v;
+}
+
+#define __CMPXCHG_CASE(w, sfx, name, sz, mb, cl...) \
+static __always_inline u##sz \
+__lse__cmpxchg_case_##name##sz(volatile void *ptr, \
+ u##sz old, \
+ u##sz new) \
+{ \
+ register unsigned long x0 asm ("x0") = (unsigned long)ptr; \
+ register u##sz x1 asm ("x1") = old; \
+ register u##sz x2 asm ("x2") = new; \
+ unsigned long tmp; \
+ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " mov %" #w "[tmp], %" #w "[old]\n" \
+ " cas" #mb #sfx "\t%" #w "[tmp], %" #w "[new], %[v]\n" \
+ " mov %" #w "[ret], %" #w "[tmp]" \
+ : [ret] "+r" (x0), [v] "+Q" (*(unsigned long *)ptr), \
+ [tmp] "=&r" (tmp) \
+ : [old] "r" (x1), [new] "r" (x2) \
+ : cl); \
+ \
+ return x0; \
+}
+
+__CMPXCHG_CASE(w, b, , 8, )
+__CMPXCHG_CASE(w, h, , 16, )
+__CMPXCHG_CASE(w, , , 32, )
+__CMPXCHG_CASE(x, , , 64, )
+__CMPXCHG_CASE(w, b, acq_, 8, a, "memory")
+__CMPXCHG_CASE(w, h, acq_, 16, a, "memory")
+__CMPXCHG_CASE(w, , acq_, 32, a, "memory")
+__CMPXCHG_CASE(x, , acq_, 64, a, "memory")
+__CMPXCHG_CASE(w, b, rel_, 8, l, "memory")
+__CMPXCHG_CASE(w, h, rel_, 16, l, "memory")
+__CMPXCHG_CASE(w, , rel_, 32, l, "memory")
+__CMPXCHG_CASE(x, , rel_, 64, l, "memory")
+__CMPXCHG_CASE(w, b, mb_, 8, al, "memory")
+__CMPXCHG_CASE(w, h, mb_, 16, al, "memory")
+__CMPXCHG_CASE(w, , mb_, 32, al, "memory")
+__CMPXCHG_CASE(x, , mb_, 64, al, "memory")
+
+#undef __CMPXCHG_CASE
+
+#define __CMPXCHG_DBL(name, mb, cl...) \
+static __always_inline long \
+__lse__cmpxchg_double##name(unsigned long old1, \
+ unsigned long old2, \
+ unsigned long new1, \
+ unsigned long new2, \
+ volatile void *ptr) \
+{ \
+ unsigned long oldval1 = old1; \
+ unsigned long oldval2 = old2; \
+ register unsigned long x0 asm ("x0") = old1; \
+ register unsigned long x1 asm ("x1") = old2; \
+ register unsigned long x2 asm ("x2") = new1; \
+ register unsigned long x3 asm ("x3") = new2; \
+ register unsigned long x4 asm ("x4") = (unsigned long)ptr; \
+ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " casp" #mb "\t%[old1], %[old2], %[new1], %[new2], %[v]\n"\
+ " eor %[old1], %[old1], %[oldval1]\n" \
+ " eor %[old2], %[old2], %[oldval2]\n" \
+ " orr %[old1], %[old1], %[old2]" \
+ : [old1] "+&r" (x0), [old2] "+&r" (x1), \
+ [v] "+Q" (*(unsigned long *)ptr) \
+ : [new1] "r" (x2), [new2] "r" (x3), [ptr] "r" (x4), \
+ [oldval1] "r" (oldval1), [oldval2] "r" (oldval2) \
+ : cl); \
+ \
+ return x0; \
+}
+
+__CMPXCHG_DBL( , )
+__CMPXCHG_DBL(_mb, al, "memory")
+
+#undef __CMPXCHG_DBL
+
+#endif /* __ASM_ATOMIC_LSE_H */
\ No newline at end of file
diff --git a/xen/include/asm-arm/arm64/cmpxchg.h b/xen/include/asm-arm/arm64/cmpxchg.h
new file mode 100644
index 0000000000..c51388216e
--- /dev/null
+++ b/xen/include/asm-arm/arm64/cmpxchg.h
@@ -0,0 +1,285 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Based on arch/arm/include/asm/cmpxchg.h
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ */
+#ifndef __ASM_CMPXCHG_H
+#define __ASM_CMPXCHG_H
+
+#include <linux/build_bug.h>
+#include <linux/compiler.h>
+
+#include <asm/barrier.h>
+#include <asm/lse.h>
+
+/*
+ * We need separate acquire parameters for ll/sc and lse, since the full
+ * barrier case is generated as release+dmb for the former and
+ * acquire+release for the latter.
+ */
+#define __XCHG_CASE(w, sfx, name, sz, mb, nop_lse, acq, acq_lse, rel, cl) \
+static inline u##sz __xchg_case_##name##sz(u##sz x, volatile void *ptr) \
+{ \
+ u##sz ret; \
+ unsigned long tmp; \
+ \
+ asm volatile(ARM64_LSE_ATOMIC_INSN( \
+ /* LL/SC */ \
+ " prfm pstl1strm, %2\n" \
+ "1: ld" #acq "xr" #sfx "\t%" #w "0, %2\n" \
+ " st" #rel "xr" #sfx "\t%w1, %" #w "3, %2\n" \
+ " cbnz %w1, 1b\n" \
+ " " #mb, \
+ /* LSE atomics */ \
+ " swp" #acq_lse #rel #sfx "\t%" #w "3, %" #w "0, %2\n" \
+ __nops(3) \
+ " " #nop_lse) \
+ : "=&r" (ret), "=&r" (tmp), "+Q" (*(u##sz *)ptr) \
+ : "r" (x) \
+ : cl); \
+ \
+ return ret; \
+}
+
+__XCHG_CASE(w, b, , 8, , , , , , )
+__XCHG_CASE(w, h, , 16, , , , , , )
+__XCHG_CASE(w, , , 32, , , , , , )
+__XCHG_CASE( , , , 64, , , , , , )
+__XCHG_CASE(w, b, acq_, 8, , , a, a, , "memory")
+__XCHG_CASE(w, h, acq_, 16, , , a, a, , "memory")
+__XCHG_CASE(w, , acq_, 32, , , a, a, , "memory")
+__XCHG_CASE( , , acq_, 64, , , a, a, , "memory")
+__XCHG_CASE(w, b, rel_, 8, , , , , l, "memory")
+__XCHG_CASE(w, h, rel_, 16, , , , , l, "memory")
+__XCHG_CASE(w, , rel_, 32, , , , , l, "memory")
+__XCHG_CASE( , , rel_, 64, , , , , l, "memory")
+__XCHG_CASE(w, b, mb_, 8, dmb ish, nop, , a, l, "memory")
+__XCHG_CASE(w, h, mb_, 16, dmb ish, nop, , a, l, "memory")
+__XCHG_CASE(w, , mb_, 32, dmb ish, nop, , a, l, "memory")
+__XCHG_CASE( , , mb_, 64, dmb ish, nop, , a, l, "memory")
+
+#undef __XCHG_CASE
+
+#define __XCHG_GEN(sfx) \
+static __always_inline unsigned long __xchg##sfx(unsigned long x, \
+ volatile void *ptr, \
+ int size) \
+{ \
+ switch (size) { \
+ case 1: \
+ return __xchg_case##sfx##_8(x, ptr); \
+ case 2: \
+ return __xchg_case##sfx##_16(x, ptr); \
+ case 4: \
+ return __xchg_case##sfx##_32(x, ptr); \
+ case 8: \
+ return __xchg_case##sfx##_64(x, ptr); \
+ default: \
+ BUILD_BUG(); \
+ } \
+ \
+ unreachable(); \
+}
+
+__XCHG_GEN()
+__XCHG_GEN(_acq)
+__XCHG_GEN(_rel)
+__XCHG_GEN(_mb)
+
+#undef __XCHG_GEN
+
+#define __xchg_wrapper(sfx, ptr, x) \
+({ \
+ __typeof__(*(ptr)) __ret; \
+ __ret = (__typeof__(*(ptr))) \
+ __xchg##sfx((unsigned long)(x), (ptr), sizeof(*(ptr))); \
+ __ret; \
+})
+
+/* xchg */
+#define arch_xchg_relaxed(...) __xchg_wrapper( , __VA_ARGS__)
+#define arch_xchg_acquire(...) __xchg_wrapper(_acq, __VA_ARGS__)
+#define arch_xchg_release(...) __xchg_wrapper(_rel, __VA_ARGS__)
+#define arch_xchg(...) __xchg_wrapper( _mb, __VA_ARGS__)
+
+#define __CMPXCHG_CASE(name, sz) \
+static inline u##sz __cmpxchg_case_##name##sz(volatile void *ptr, \
+ u##sz old, \
+ u##sz new) \
+{ \
+ return __lse_ll_sc_body(_cmpxchg_case_##name##sz, \
+ ptr, old, new); \
+}
+
+__CMPXCHG_CASE( , 8)
+__CMPXCHG_CASE( , 16)
+__CMPXCHG_CASE( , 32)
+__CMPXCHG_CASE( , 64)
+__CMPXCHG_CASE(acq_, 8)
+__CMPXCHG_CASE(acq_, 16)
+__CMPXCHG_CASE(acq_, 32)
+__CMPXCHG_CASE(acq_, 64)
+__CMPXCHG_CASE(rel_, 8)
+__CMPXCHG_CASE(rel_, 16)
+__CMPXCHG_CASE(rel_, 32)
+__CMPXCHG_CASE(rel_, 64)
+__CMPXCHG_CASE(mb_, 8)
+__CMPXCHG_CASE(mb_, 16)
+__CMPXCHG_CASE(mb_, 32)
+__CMPXCHG_CASE(mb_, 64)
+
+#undef __CMPXCHG_CASE
+
+#define __CMPXCHG_DBL(name) \
+static inline long __cmpxchg_double##name(unsigned long old1, \
+ unsigned long old2, \
+ unsigned long new1, \
+ unsigned long new2, \
+ volatile void *ptr) \
+{ \
+ return __lse_ll_sc_body(_cmpxchg_double##name, \
+ old1, old2, new1, new2, ptr); \
+}
+
+__CMPXCHG_DBL( )
+__CMPXCHG_DBL(_mb)
+
+#undef __CMPXCHG_DBL
+
+#define __CMPXCHG_GEN(sfx) \
+static __always_inline unsigned long __cmpxchg##sfx(volatile void *ptr, \
+ unsigned long old, \
+ unsigned long new, \
+ int size) \
+{ \
+ switch (size) { \
+ case 1: \
+ return __cmpxchg_case##sfx##_8(ptr, old, new); \
+ case 2: \
+ return __cmpxchg_case##sfx##_16(ptr, old, new); \
+ case 4: \
+ return __cmpxchg_case##sfx##_32(ptr, old, new); \
+ case 8: \
+ return __cmpxchg_case##sfx##_64(ptr, old, new); \
+ default: \
+ BUILD_BUG(); \
+ } \
+ \
+ unreachable(); \
+}
+
+__CMPXCHG_GEN()
+__CMPXCHG_GEN(_acq)
+__CMPXCHG_GEN(_rel)
+__CMPXCHG_GEN(_mb)
+
+#undef __CMPXCHG_GEN
+
+#define __cmpxchg_wrapper(sfx, ptr, o, n) \
+({ \
+ __typeof__(*(ptr)) __ret; \
+ __ret = (__typeof__(*(ptr))) \
+ __cmpxchg##sfx((ptr), (unsigned long)(o), \
+ (unsigned long)(n), sizeof(*(ptr))); \
+ __ret; \
+})
+
+/* cmpxchg */
+#define arch_cmpxchg_relaxed(...) __cmpxchg_wrapper( , __VA_ARGS__)
+#define arch_cmpxchg_acquire(...) __cmpxchg_wrapper(_acq, __VA_ARGS__)
+#define arch_cmpxchg_release(...) __cmpxchg_wrapper(_rel, __VA_ARGS__)
+#define arch_cmpxchg(...) __cmpxchg_wrapper( _mb, __VA_ARGS__)
+#define arch_cmpxchg_local arch_cmpxchg_relaxed
+
+/* cmpxchg64 */
+#define arch_cmpxchg64_relaxed arch_cmpxchg_relaxed
+#define arch_cmpxchg64_acquire arch_cmpxchg_acquire
+#define arch_cmpxchg64_release arch_cmpxchg_release
+#define arch_cmpxchg64 arch_cmpxchg
+#define arch_cmpxchg64_local arch_cmpxchg_local
+
+/* cmpxchg_double */
+#define system_has_cmpxchg_double() 1
+
+#define __cmpxchg_double_check(ptr1, ptr2) \
+({ \
+ if (sizeof(*(ptr1)) != 8) \
+ BUILD_BUG(); \
+ VM_BUG_ON((unsigned long *)(ptr2) - (unsigned long *)(ptr1) != 1); \
+})
+
+#define arch_cmpxchg_double(ptr1, ptr2, o1, o2, n1, n2) \
+({ \
+ int __ret; \
+ __cmpxchg_double_check(ptr1, ptr2); \
+ __ret = !__cmpxchg_double_mb((unsigned long)(o1), (unsigned long)(o2), \
+ (unsigned long)(n1), (unsigned long)(n2), \
+ ptr1); \
+ __ret; \
+})
+
+#define arch_cmpxchg_double_local(ptr1, ptr2, o1, o2, n1, n2) \
+({ \
+ int __ret; \
+ __cmpxchg_double_check(ptr1, ptr2); \
+ __ret = !__cmpxchg_double((unsigned long)(o1), (unsigned long)(o2), \
+ (unsigned long)(n1), (unsigned long)(n2), \
+ ptr1); \
+ __ret; \
+})
+
+#define __CMPWAIT_CASE(w, sfx, sz) \
+static inline void __cmpwait_case_##sz(volatile void *ptr, \
+ unsigned long val) \
+{ \
+ unsigned long tmp; \
+ \
+ asm volatile( \
+ " sevl\n" \
+ " wfe\n" \
+ " ldxr" #sfx "\t%" #w "[tmp], %[v]\n" \
+ " eor %" #w "[tmp], %" #w "[tmp], %" #w "[val]\n" \
+ " cbnz %" #w "[tmp], 1f\n" \
+ " wfe\n" \
+ "1:" \
+ : [tmp] "=&r" (tmp), [v] "+Q" (*(unsigned long *)ptr) \
+ : [val] "r" (val)); \
+}
+
+__CMPWAIT_CASE(w, b, 8);
+__CMPWAIT_CASE(w, h, 16);
+__CMPWAIT_CASE(w, , 32);
+__CMPWAIT_CASE( , , 64);
+
+#undef __CMPWAIT_CASE
+
+#define __CMPWAIT_GEN(sfx) \
+static __always_inline void __cmpwait##sfx(volatile void *ptr, \
+ unsigned long val, \
+ int size) \
+{ \
+ switch (size) { \
+ case 1: \
+ return __cmpwait_case##sfx##_8(ptr, (u8)val); \
+ case 2: \
+ return __cmpwait_case##sfx##_16(ptr, (u16)val); \
+ case 4: \
+ return __cmpwait_case##sfx##_32(ptr, val); \
+ case 8: \
+ return __cmpwait_case##sfx##_64(ptr, val); \
+ default: \
+ BUILD_BUG(); \
+ } \
+ \
+ unreachable(); \
+}
+
+__CMPWAIT_GEN()
+
+#undef __CMPWAIT_GEN
+
+#define __cmpwait_relaxed(ptr, val) \
+ __cmpwait((ptr), (unsigned long)(val), sizeof(*(ptr)))
+
+#endif /* __ASM_CMPXCHG_H */
\ No newline at end of file
diff --git a/xen/include/asm-arm/arm64/lse.h b/xen/include/asm-arm/arm64/lse.h
new file mode 100644
index 0000000000..704be3e4e4
--- /dev/null
+++ b/xen/include/asm-arm/arm64/lse.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_LSE_H
+#define __ASM_LSE_H
+
+#include <asm/atomic_ll_sc.h>
+
+#ifdef CONFIG_ARM64_LSE_ATOMICS
+
+#define __LSE_PREAMBLE ".arch_extension lse\n"
+
+#include <linux/compiler_types.h>
+#include <linux/export.h>
+#include <linux/jump_label.h>
+#include <linux/stringify.h>
+#include <asm/alternative.h>
+#include <asm/atomic_lse.h>
+#include <asm/cpucaps.h>
+
+extern struct static_key_false cpu_hwcap_keys[ARM64_NCAPS];
+extern struct static_key_false arm64_const_caps_ready;
+
+static inline bool system_uses_lse_atomics(void)
+{
+ return (static_branch_likely(&arm64_const_caps_ready)) &&
+ static_branch_likely(&cpu_hwcap_keys[ARM64_HAS_LSE_ATOMICS]);
+}
+
+#define __lse_ll_sc_body(op, ...) \
+({ \
+ system_uses_lse_atomics() ? \
+ __lse_##op(__VA_ARGS__) : \
+ __ll_sc_##op(__VA_ARGS__); \
+})
+
+/* In-line patching at runtime */
+#define ARM64_LSE_ATOMIC_INSN(llsc, lse) \
+ ALTERNATIVE(llsc, __LSE_PREAMBLE lse, ARM64_HAS_LSE_ATOMICS)
+
+#else /* CONFIG_ARM64_LSE_ATOMICS */
+
+static inline bool system_uses_lse_atomics(void) { return false; }
+
+#define __lse_ll_sc_body(op, ...) __ll_sc_##op(__VA_ARGS__)
+
+#define ARM64_LSE_ATOMIC_INSN(llsc, lse) llsc
+
+#endif /* CONFIG_ARM64_LSE_ATOMICS */
+#endif /* __ASM_LSE_H */
\ No newline at end of file
diff --git a/xen/include/xen/rwonce.h b/xen/include/xen/rwonce.h
new file mode 100644
index 0000000000..6b47392d1c
--- /dev/null
+++ b/xen/include/xen/rwonce.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Prevent the compiler from merging or refetching reads or writes. The
+ * compiler is also forbidden from reordering successive instances of
+ * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some
+ * particular ordering. One way to make the compiler aware of ordering is to
+ * put the two invocations of READ_ONCE or WRITE_ONCE in different C
+ * statements.
+ *
+ * These two macros will also work on aggregate data types like structs or
+ * unions.
+ *
+ * Their two major use cases are: (1) Mediating communication between
+ * process-level code and irq/NMI handlers, all running on the same CPU,
+ * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
+ * mutilate accesses that either do not require ordering or that interact
+ * with an explicit memory barrier or atomic instruction that provides the
+ * required ordering.
+ */
+#ifndef __ASM_GENERIC_RWONCE_H
+#define __ASM_GENERIC_RWONCE_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/compiler_types.h>
+#include <linux/kasan-checks.h>
+#include <linux/kcsan-checks.h>
+
+/*
+ * Yes, this permits 64-bit accesses on 32-bit architectures. These will
+ * actually be atomic in some cases (namely Armv7 + LPAE), but for others we
+ * rely on the access being split into 2x32-bit accesses for a 32-bit quantity
+ * (e.g. a virtual address) and a strong prevailing wind.
+ */
+#define compiletime_assert_rwonce_type(t) \
+ compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \
+ "Unsupported access size for {READ,WRITE}_ONCE().")
+
+/*
+ * Use __READ_ONCE() instead of READ_ONCE() if you do not require any
+ * atomicity. Note that this may result in tears!
+ */
+#ifndef __READ_ONCE
+#define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x))
+#endif
+
+#define READ_ONCE(x) \
+({ \
+ compiletime_assert_rwonce_type(x); \
+ __READ_ONCE(x); \
+})
+
+#define __WRITE_ONCE(x, val) \
+do { \
+ *(volatile typeof(x) *)&(x) = (val); \
+} while (0)
+
+#define WRITE_ONCE(x, val) \
+do { \
+ compiletime_assert_rwonce_type(x); \
+ __WRITE_ONCE(x, val); \
+} while (0)
+
+static __no_sanitize_or_inline
+unsigned long __read_once_word_nocheck(const void *addr)
+{
+ return __READ_ONCE(*(unsigned long *)addr);
+}
+
+/*
+ * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need to load a
+ * word from memory atomically but without telling KASAN/KCSAN. This is
+ * usually used by unwinding code when walking the stack of a running process.
+ */
+#define READ_ONCE_NOCHECK(x) \
+({ \
+ compiletime_assert(sizeof(x) == sizeof(unsigned long), \
+ "Unsupported access size for READ_ONCE_NOCHECK()."); \
+ (typeof(x))__read_once_word_nocheck(&(x)); \
+})
+
+static __no_kasan_or_inline
+unsigned long read_word_at_a_time(const void *addr)
+{
+ kasan_check_read(addr, 1);
+ return *(unsigned long *)addr;
+}
+
+#endif /* __ASSEMBLY__ */
+#endif /* __ASM_GENERIC_RWONCE_H */
\ No newline at end of file
--
2.24.3 (Apple Git-128)
On 11.11.2020 22:51, Ash Wilding wrote:
> From: Ash Wilding <ash.j.wilding@gmail.com>
>
> This patch pulls in Linux's atomics helpers for arm32 and arm64, and
> their dependencies, as-is.
>
> Note that Linux's arm32 atomics helpers use the READ_ONCE() and
> WRITE_ONCE() macros defined in <asm-generic/rwonce.h>, while Linux's
> arm64 atomics helpers use __READ_ONCE() and __WRITE_ONCE().
And our ACCESS_ONCE() can't be used, or be made usable? I don't think
we want a 3rd variant when we're already in the process of discussing
how to fold the two ones we have right now.
> The only difference is that the __* versions skip checking whether the
> object being accessed is the same size as a native C type (e.g. char,
> int, long, etc). Given the arm32 helpers are using the macros to access
> an atomic_t's counter member, which is an int, we can skip this check by
> using the __* versions like the arm64 code does.
>
> I mention this here because it forms the first part of my justification
> for *not* copying Linux's <linux/compiler_types.h> to Xen; the size
> check described above is performed by __native_word() defined in that
> header.
>
> The second part of my justification may be more contentious; as you'll
> see in the next patch, I intend to drop the __unqual_scalar_typeof()
> calls in __READ_ONCE() and __WRITE_ONCE(). This is because the pointer
> to the atomic_t's counter member is always a basic (int *) so we don't
> need this, and dropping it means we can avoid having to port Linux's
> <linux/compiler_types.h>.
I don't think weakening the checking is a good idea when the macros
are being made available for general use. If they'd be renamed to be
private flavors for use just in Arm's atomics, this would be a
different thing.
> If people are against this approach, please bear in mind that the
> current version of __unqual_scalar_typeof() in <linux/compiler_types.h>
> was actually the reason for Linux upgrading the minimum GCC version
> required to 4.9 earlier this year so that they can guarantee C11
> _Generic support [1].
>
> So if we do want to take Linux's <linux/compiler_types.h> we'll either
> need to:
>
> A) bump up the minimum required version of GCC to 4.9 to match
> that required by Linux; in the Xen README we currently state
> GCC 4.8 for Arm and GCC 4.1.2_20070115 for x86.
Discussion about bumping the baseline has started, but is progressing
rather slowly. I'm not an Arm maintainer, but it would seem to me
that going from 4.8 to 4.9 just for Arm at this point may be easier
than the decision what the new baseline ought to be for x86.
> --- /dev/null
> +++ b/xen/include/xen/rwonce.h
> @@ -0,0 +1,90 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Prevent the compiler from merging or refetching reads or writes. The
> + * compiler is also forbidden from reordering successive instances of
> + * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some
> + * particular ordering. One way to make the compiler aware of ordering is to
> + * put the two invocations of READ_ONCE or WRITE_ONCE in different C
> + * statements.
> + *
> + * These two macros will also work on aggregate data types like structs or
> + * unions.
> + *
> + * Their two major use cases are: (1) Mediating communication between
> + * process-level code and irq/NMI handlers, all running on the same CPU,
> + * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
> + * mutilate accesses that either do not require ordering or that interact
> + * with an explicit memory barrier or atomic instruction that provides the
> + * required ordering.
> + */
> +#ifndef __ASM_GENERIC_RWONCE_H
> +#define __ASM_GENERIC_RWONCE_H
> +
> +#ifndef __ASSEMBLY__
> +
> +#include <linux/compiler_types.h>
> +#include <linux/kasan-checks.h>
> +#include <linux/kcsan-checks.h>
> +
> +/*
> + * Yes, this permits 64-bit accesses on 32-bit architectures. These will
> + * actually be atomic in some cases (namely Armv7 + LPAE), but for others we
> + * rely on the access being split into 2x32-bit accesses for a 32-bit quantity
> + * (e.g. a virtual address) and a strong prevailing wind.
> + */
> +#define compiletime_assert_rwonce_type(t) \
> + compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \
> + "Unsupported access size for {READ,WRITE}_ONCE().")
> +
> +/*
> + * Use __READ_ONCE() instead of READ_ONCE() if you do not require any
> + * atomicity. Note that this may result in tears!
> + */
> +#ifndef __READ_ONCE
> +#define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x))
> +#endif
> +
> +#define READ_ONCE(x) \
> +({ \
> + compiletime_assert_rwonce_type(x); \
> + __READ_ONCE(x); \
> +})
> +
> +#define __WRITE_ONCE(x, val) \
> +do { \
> + *(volatile typeof(x) *)&(x) = (val); \
> +} while (0)
> +
> +#define WRITE_ONCE(x, val) \
> +do { \
> + compiletime_assert_rwonce_type(x); \
> + __WRITE_ONCE(x, val); \
> +} while (0)
> +
> +static __no_sanitize_or_inline
> +unsigned long __read_once_word_nocheck(const void *addr)
> +{
> + return __READ_ONCE(*(unsigned long *)addr);
> +}
> +
> +/*
> + * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need to load a
> + * word from memory atomically but without telling KASAN/KCSAN. This is
> + * usually used by unwinding code when walking the stack of a running process.
> + */
> +#define READ_ONCE_NOCHECK(x) \
> +({ \
> + compiletime_assert(sizeof(x) == sizeof(unsigned long), \
> + "Unsupported access size for READ_ONCE_NOCHECK()."); \
> + (typeof(x))__read_once_word_nocheck(&(x)); \
> +})
> +
> +static __no_kasan_or_inline
> +unsigned long read_word_at_a_time(const void *addr)
> +{
> + kasan_check_read(addr, 1);
> + return *(unsigned long *)addr;
> +}
> +
> +#endif /* __ASSEMBLY__ */
> +#endif /* __ASM_GENERIC_RWONCE_H */
> \ No newline at end of file
This wants taking care of in any event - there are multiple instances
in this patch (in fact it looks as if all of the new files had this
issue), and I didn't check others.
Jan
Hey Jan, >> >> Note that Linux's arm32 atomics helpers use the READ_ONCE() and >> WRITE_ONCE() macros defined in <asm-generic/rwonce.h>, while Linux's >> arm64 atomics helpers use __READ_ONCE() and __WRITE_ONCE(). > > And our ACCESS_ONCE() can't be used, or be made usable? I don't think > we want a 3rd variant when we're already in the process of discussing > how to fold the two ones we have right now. Many thanks for the pointer, I'm still familiarising myself with Xen's codebase and wasn't aware of ACCESS_ONCE(); yes, that's exactly what we need which means we can drop Linux's <asm-generic/rwonce.h> completely. That also means: > > I don't think weakening the checking is a good idea when the macros > are being made available for general use. If they'd be renamed to be > private flavors for use just in Arm's atomics, this would be a > different thing. This problem goes away, as does the need/desire to bump the minimum GCC version up to 4.9 for xen/arm just to support the usage of C11 _Generic in Linux's <linux/compiler_types.h>. That said, agreed, I did think the way I'd done it was a tad suspect hence the "possibly contentious" disclaimer :-) I'll keep this in mind for similar porting work in future. >> >> \ No newline at end of file > > This wants taking care of in any event - there are multiple instances > in this patch (in fact it looks as if all of the new files had this > issue), and I didn't check others. Ack, will fix. Thanks for taking the time to provide feedback! Cheers, Ash.
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