| Message ID | 20241010101510.1487477-2-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | arm64: stacktrace: improve unwind reporting | expand |
On Thu, Oct 10, 2024 at 11:15:01AM +0100, Mark Rutland wrote: > To ensure that the stack is correctly aligned when branching to C code, > we require struct pt_regs to be a multiple of 16 bytes, as noted in a > comment. > > Add an explicit assertion for this, so that any accidental violation of > this requirement will be caught by the compiler. Reviewed-by: Mark Brown <broonie@kernel.org>
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h index 0abe975d68a8e..10eca3a3fed49 100644 --- a/arch/arm64/include/asm/ptrace.h +++ b/arch/arm64/include/asm/ptrace.h @@ -149,8 +149,7 @@ static inline unsigned long pstate_to_compat_psr(const unsigned long pstate) /* * This struct defines the way the registers are stored on the stack during an - * exception. Note that sizeof(struct pt_regs) has to be a multiple of 16 (for - * stack alignment). struct user_pt_regs must form a prefix of struct pt_regs. + * exception. struct user_pt_regs must form a prefix of struct pt_regs. */ struct pt_regs { union { @@ -180,6 +179,9 @@ struct pt_regs { u64 exit_rcu; }; +/* For correct stack alignment, pt_regs has to be a multiple of 16 bytes. */ +static_assert(IS_ALIGNED(sizeof(struct pt_regs), 16)); + static inline bool in_syscall(struct pt_regs const *regs) { return regs->syscallno != NO_SYSCALL;
To ensure that the stack is correctly aligned when branching to C code, we require struct pt_regs to be a multiple of 16 bytes, as noted in a comment. Add an explicit assertion for this, so that any accidental violation of this requirement will be caught by the compiler. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Josh Poimboeuf <jpoimboe@kernel.org> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Brown <broonie@kernel.org> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Puranjay Mohan <puranjay12@gmail.com> Cc: Will Deacon <will@kernel.org> --- arch/arm64/include/asm/ptrace.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)