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Peter Anvin" , Thomas Gleixner , Borislav Petkov , Ard Biesheuvel , Uros Bizjak , Brian Gerst Subject: [RFC PATCH 05/11] x86/percpu: Move top_of_stack to percpu hot section Date: Sat, 22 Feb 2025 14:06:17 -0500 Message-ID: <20250222190623.262689-6-brgerst@gmail.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250222190623.262689-1-brgerst@gmail.com> References: <20250222190623.262689-1-brgerst@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" No functional change. Signed-off-by: Brian Gerst --- arch/x86/entry/entry_32.S | 4 ++-- arch/x86/entry/entry_64.S | 6 +++--- arch/x86/entry/entry_64_compat.S | 4 ++-- arch/x86/include/asm/current.h | 1 - arch/x86/include/asm/percpu.h | 2 +- arch/x86/include/asm/processor.h | 8 ++++++-- arch/x86/kernel/asm-offsets.c | 1 - arch/x86/kernel/cpu/common.c | 3 ++- arch/x86/kernel/process_32.c | 4 ++-- arch/x86/kernel/process_64.c | 2 +- arch/x86/kernel/smpboot.c | 2 +- arch/x86/kernel/vmlinux.lds.S | 1 + 12 files changed, 21 insertions(+), 17 deletions(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 20be5758c2d2..92c0b4a94e0a 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -1153,7 +1153,7 @@ SYM_CODE_START(asm_exc_nmi) * is using the thread stack right now, so it's safe for us to use it. */ movl %esp, %ebx - movl PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %esp + movl PER_CPU_VAR(cpu_current_top_of_stack), %esp call exc_nmi movl %ebx, %esp =20 @@ -1217,7 +1217,7 @@ SYM_CODE_START(rewind_stack_and_make_dead) /* Prevent any naive code from trying to unwind to our caller. */ xorl %ebp, %ebp =20 - movl PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %esi + movl PER_CPU_VAR(cpu_current_top_of_stack), %esi leal -TOP_OF_KERNEL_STACK_PADDING-PTREGS_SIZE(%esi), %esp =20 call make_task_dead diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 33a955aa01d8..9baf32a7a118 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -92,7 +92,7 @@ SYM_CODE_START(entry_SYSCALL_64) /* tss.sp2 is scratch space. */ movq %rsp, PER_CPU_VAR(cpu_tss_rw + TSS_sp2) SWITCH_TO_KERNEL_CR3 scratch_reg=3D%rsp - movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rsp + movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp =20 SYM_INNER_LABEL(entry_SYSCALL_64_safe_stack, SYM_L_GLOBAL) ANNOTATE_NOENDBR @@ -1166,7 +1166,7 @@ SYM_CODE_START(asm_exc_nmi) FENCE_SWAPGS_USER_ENTRY SWITCH_TO_KERNEL_CR3 scratch_reg=3D%rdx movq %rsp, %rdx - movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rsp + movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp UNWIND_HINT_IRET_REGS base=3D%rdx offset=3D8 pushq 5*8(%rdx) /* pt_regs->ss */ pushq 4*8(%rdx) /* pt_regs->rsp */ @@ -1484,7 +1484,7 @@ SYM_CODE_START_NOALIGN(rewind_stack_and_make_dead) /* Prevent any naive code from trying to unwind to our caller. */ xorl %ebp, %ebp =20 - movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rax + movq PER_CPU_VAR(cpu_current_top_of_stack), %rax leaq -PTREGS_SIZE(%rax), %rsp UNWIND_HINT_REGS =20 diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_com= pat.S index ed0a5f2dc129..a45e1125fc6c 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -57,7 +57,7 @@ SYM_CODE_START(entry_SYSENTER_compat) SWITCH_TO_KERNEL_CR3 scratch_reg=3D%rax popq %rax =20 - movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rsp + movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp =20 /* Construct struct pt_regs on stack */ pushq $__USER_DS /* pt_regs->ss */ @@ -193,7 +193,7 @@ SYM_CODE_START(entry_SYSCALL_compat) SWITCH_TO_KERNEL_CR3 scratch_reg=3D%rsp =20 /* Switch to the kernel stack */ - movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rsp + movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp =20 SYM_INNER_LABEL(entry_SYSCALL_compat_safe_stack, SYM_L_GLOBAL) ANNOTATE_NOENDBR diff --git a/arch/x86/include/asm/current.h b/arch/x86/include/asm/current.h index fbc7eb92adb2..8adbe0e3c5e7 100644 --- a/arch/x86/include/asm/current.h +++ b/arch/x86/include/asm/current.h @@ -16,7 +16,6 @@ struct pcpu_hot { union { struct { struct task_struct *current_task; - unsigned long top_of_stack; void *hardirq_stack_ptr; u16 softirq_pending; #ifdef CONFIG_X86_64 diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h index 1a76eb87c5d8..cc19bd785f0e 100644 --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -560,7 +560,7 @@ do { \ * it is accessed while this_cpu_read_stable() allows the value to be cach= ed. * this_cpu_read_stable() is more efficient and can be used if its value * is guaranteed to be valid across CPUs. The current users include - * pcpu_hot.current_task and pcpu_hot.top_of_stack, both of which are + * pcpu_hot.current_task and cpu_current_top_of_stack, both of which are * actually per-thread variables implemented as per-CPU variables and * thus stable for the duration of the respective task. */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/proces= sor.h index b3d153730f63..1505cb1d09a8 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -420,6 +420,10 @@ struct irq_stack { char stack[IRQ_STACK_SIZE]; } __aligned(IRQ_STACK_SIZE); =20 +DECLARE_PER_CPU_HOT(unsigned long, cpu_current_top_of_stack); +/* const-qualified alias provided by the linker. */ +DECLARE_PER_CPU_HOT(const unsigned long, const_cpu_current_top_of_stack); + #ifdef CONFIG_X86_64 static inline unsigned long cpu_kernelmode_gs_base(int cpu) { @@ -545,9 +549,9 @@ static __always_inline unsigned long current_top_of_sta= ck(void) * entry trampoline. */ if (IS_ENABLED(CONFIG_USE_X86_SEG_SUPPORT)) - return this_cpu_read_const(const_pcpu_hot.top_of_stack); + return this_cpu_read_const(const_cpu_current_top_of_stack); =20 - return this_cpu_read_stable(pcpu_hot.top_of_stack); + return this_cpu_read_stable(cpu_current_top_of_stack); } =20 static __always_inline bool on_thread_stack(void) diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index 6fae88f8ae1e..54ace808defd 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -107,7 +107,6 @@ static void __used common(void) OFFSET(TSS_sp0, tss_struct, x86_tss.sp0); OFFSET(TSS_sp1, tss_struct, x86_tss.sp1); OFFSET(TSS_sp2, tss_struct, x86_tss.sp2); - OFFSET(X86_top_of_stack, pcpu_hot, top_of_stack); OFFSET(X86_current_task, pcpu_hot, current_task); #if IS_ENABLED(CONFIG_CRYPTO_ARIA_AESNI_AVX_X86_64) /* Offset for fields in aria_ctx */ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 519e2ec2027d..25a5806e15aa 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2016,7 +2016,6 @@ __setup("clearcpuid=3D", setup_clearcpuid); =20 DEFINE_PER_CPU_ALIGNED(struct pcpu_hot, pcpu_hot) =3D { .current_task =3D &init_task, - .top_of_stack =3D TOP_OF_INIT_STACK, }; EXPORT_PER_CPU_SYMBOL(pcpu_hot); EXPORT_PER_CPU_SYMBOL(const_pcpu_hot); @@ -2024,6 +2023,8 @@ EXPORT_PER_CPU_SYMBOL(const_pcpu_hot); DEFINE_PER_CPU_HOT(int, __preempt_count) =3D INIT_PREEMPT_COUNT; EXPORT_PER_CPU_SYMBOL(__preempt_count); =20 +DEFINE_PER_CPU_HOT(unsigned long, cpu_current_top_of_stack) =3D TOP_OF_INI= T_STACK; + #ifdef CONFIG_X86_64 static void wrmsrl_cstar(unsigned long val) { diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 0917c7f25720..3afb2428bedb 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -190,13 +190,13 @@ __switch_to(struct task_struct *prev_p, struct task_s= truct *next_p) arch_end_context_switch(next_p); =20 /* - * Reload esp0 and pcpu_hot.top_of_stack. This changes + * Reload esp0 and cpu_current_top_of_stack. This changes * current_thread_info(). Refresh the SYSENTER configuration in * case prev or next is vm86. */ update_task_stack(next_p); refresh_sysenter_cs(next); - this_cpu_write(pcpu_hot.top_of_stack, + this_cpu_write(cpu_current_top_of_stack, (unsigned long)task_stack_page(next_p) + THREAD_SIZE); =20 diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 226472332a70..4252b11718f2 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -669,7 +669,7 @@ __switch_to(struct task_struct *prev_p, struct task_str= uct *next_p) * Switch the PDA and FPU contexts. */ raw_cpu_write(pcpu_hot.current_task, next_p); - raw_cpu_write(pcpu_hot.top_of_stack, task_top_of_stack(next_p)); + raw_cpu_write(cpu_current_top_of_stack, task_top_of_stack(next_p)); =20 switch_fpu_finish(next_p); =20 diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index c10850ae6f09..15e054f4cbf6 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -851,7 +851,7 @@ int common_cpu_up(unsigned int cpu, struct task_struct = *idle) =20 #ifdef CONFIG_X86_32 /* Stack for startup_32 can be just as for start_secondary onwards */ - per_cpu(pcpu_hot.top_of_stack, cpu) =3D task_top_of_stack(idle); + per_cpu(cpu_current_top_of_stack, cpu) =3D task_top_of_stack(idle); #endif return 0; } diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 049485513f3c..ee019c1ea859 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -44,6 +44,7 @@ ENTRY(phys_startup_64) =20 jiffies =3D jiffies_64; const_pcpu_hot =3D pcpu_hot; +const_cpu_current_top_of_stack =3D cpu_current_top_of_stack; =20 #if defined(CONFIG_X86_64) /* --=20 2.48.1