Some caller-saved registers which are not defined as function arguments
in the ABI can still be passed as arguments when the kernel is compiled
with Clang. As a result, we must save and restore those registers to
prevent ftrace from clobbering them.
- [1]: https://reviews.llvm.org/D68559
Reported-by: Evgenii Shatokhin <e.shatokhin@yadro.com>
Closes: https://lore.kernel.org/linux-riscv/7e7c7914-445d-426d-89a0-59a9199c45b1@yadro.com/
Acked-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
---
arch/riscv/include/asm/ftrace.h | 7 +++++++
arch/riscv/kernel/asm-offsets.c | 7 +++++++
arch/riscv/kernel/mcount-dyn.S | 16 ++++++++++++++--
3 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 9eb31a7ea0aa..5f81c53dbfd9 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -144,6 +144,13 @@ struct ftrace_regs {
unsigned long a5;
unsigned long a6;
unsigned long a7;
+#ifdef CONFIG_CC_IS_CLANG
+ unsigned long t2;
+ unsigned long t3;
+ unsigned long t4;
+ unsigned long t5;
+ unsigned long t6;
+#endif
};
};
};
diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
index b09ca5f944f7..db5a26fcc9ae 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -497,6 +497,13 @@ void asm_offsets(void)
DEFINE(FREGS_SP, offsetof(struct ftrace_regs, sp));
DEFINE(FREGS_S0, offsetof(struct ftrace_regs, s0));
DEFINE(FREGS_T1, offsetof(struct ftrace_regs, t1));
+#ifdef CONFIG_CC_IS_CLANG
+ DEFINE(FREGS_T2, offsetof(struct ftrace_regs, t2));
+ DEFINE(FREGS_T3, offsetof(struct ftrace_regs, t3));
+ DEFINE(FREGS_T4, offsetof(struct ftrace_regs, t4));
+ DEFINE(FREGS_T5, offsetof(struct ftrace_regs, t5));
+ DEFINE(FREGS_T6, offsetof(struct ftrace_regs, t6));
+#endif
DEFINE(FREGS_A0, offsetof(struct ftrace_regs, a0));
DEFINE(FREGS_A1, offsetof(struct ftrace_regs, a1));
DEFINE(FREGS_A2, offsetof(struct ftrace_regs, a2));
diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S
index 745dd4c4a69c..e988bd26b28b 100644
--- a/arch/riscv/kernel/mcount-dyn.S
+++ b/arch/riscv/kernel/mcount-dyn.S
@@ -96,7 +96,13 @@
REG_S x8, FREGS_S0(sp)
#endif
REG_S x6, FREGS_T1(sp)
-
+#ifdef CONFIG_CC_IS_CLANG
+ REG_S x7, FREGS_T2(sp)
+ REG_S x28, FREGS_T3(sp)
+ REG_S x29, FREGS_T4(sp)
+ REG_S x30, FREGS_T5(sp)
+ REG_S x31, FREGS_T6(sp)
+#endif
// save the arguments
REG_S x10, FREGS_A0(sp)
REG_S x11, FREGS_A1(sp)
@@ -115,7 +121,13 @@
REG_L x8, FREGS_S0(sp)
#endif
REG_L x6, FREGS_T1(sp)
-
+#ifdef CONFIG_CC_IS_CLANG
+ REG_L x7, FREGS_T2(sp)
+ REG_L x28, FREGS_T3(sp)
+ REG_L x29, FREGS_T4(sp)
+ REG_L x30, FREGS_T5(sp)
+ REG_L x31, FREGS_T6(sp)
+#endif
// restore the arguments
REG_L x10, FREGS_A0(sp)
REG_L x11, FREGS_A1(sp)
--
2.43.0Andy Chiu <andy.chiu@sifive.com> writes: > Some caller-saved registers which are not defined as function arguments > in the ABI can still be passed as arguments when the kernel is compiled > with Clang. As a result, we must save and restore those registers to > prevent ftrace from clobbering them. > > - [1]: https://reviews.llvm.org/D68559 > > Reported-by: Evgenii Shatokhin <e.shatokhin@yadro.com> > Closes: https://lore.kernel.org/linux-riscv/7e7c7914-445d-426d-89a0-59a9199c45b1@yadro.com/ > Acked-by: Nathan Chancellor <nathan@kernel.org> > Signed-off-by: Andy Chiu <andy.chiu@sifive.com> Shouldn't this be a separate fix? Still reading the details, but it smells like something what should be disabled when building w/ LLVM, no? Björn
On Tue, Aug 13, 2024 at 7:09 PM Björn Töpel <bjorn@kernel.org> wrote: > > Andy Chiu <andy.chiu@sifive.com> writes: > > > Some caller-saved registers which are not defined as function arguments > > in the ABI can still be passed as arguments when the kernel is compiled > > with Clang. As a result, we must save and restore those registers to > > prevent ftrace from clobbering them. > > > > - [1]: https://reviews.llvm.org/D68559 > > > > Reported-by: Evgenii Shatokhin <e.shatokhin@yadro.com> > > Closes: https://lore.kernel.org/linux-riscv/7e7c7914-445d-426d-89a0-59a9199c45b1@yadro.com/ > > Acked-by: Nathan Chancellor <nathan@kernel.org> > > Signed-off-by: Andy Chiu <andy.chiu@sifive.com> > > Shouldn't this be a separate fix? Still reading the details, but it > smells like something what should be disabled when building w/ LLVM, no? Yes, this is a fix. My intention was indicating the dependency. So people won't hit into trouble testing it. I can send it in a separate series. Thanks, Andy
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