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arm64: pt_regs: assert pt_regs is a multiple of 16 bytes

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To ensure that the stack is correctly aligned when branching to C code,
we require that struct pt_regs is 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>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Puranjay Mohan <puranjay12@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
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: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241017092538.1859841-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Rutland 2024-10-17 10:25:29 +01:00 committed by Catalin Marinas
parent 9852d85ec9
commit c87df9cb9a
1 changed files with 4 additions and 2 deletions
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6
arch/arm64/include/asm/ptrace.h
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@ -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;