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aarch64: skip copy of RA state register into target context

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The RA state register is local to a frame, so it should not be copied to
the target frame during the context installation.

This patch adds a new backend handler that check whether a register
needs to be skipped or not before its installation.

libgcc/ChangeLog:

	* config/aarch64/aarch64-unwind.h
	(MD_FRAME_LOCAL_REGISTER_P): new handler checking whether a register
	from the current context needs to be skipped before installation into
	the target context.
	(aarch64_frame_local_register): Likewise.
	* unwind-dw2.c (uw_install_context_1): use MD_FRAME_LOCAL_REGISTER_P.
This commit is contained in:
Matthieu Longo 2024-09-23 15:03:35 +01:00 • committed by Tamar Christina
parent f531673917
commit ba3e597681
2 changed files with 16 additions and 0 deletions
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11
libgcc/config/aarch64/aarch64-unwind.h
View file

@ -53,6 +53,9 @@ typedef enum {
#define MD_DEMANGLE_RETURN_ADDR(context, fs, addr) \
aarch64_demangle_return_addr (context, fs, addr)
#define MD_FRAME_LOCAL_REGISTER_P(reg) \
aarch64_frame_local_register (reg)
static inline aarch64_ra_signing_method_t
aarch64_context_ra_state_get (struct _Unwind_Context *context)
{
@ -127,6 +130,14 @@ aarch64_arch_extension_frame_init (struct _Unwind_Context *context ATTRIBUTE_UNU
aarch64_fs_ra_state_set (fs, aarch64_ra_no_signing);
}
/* Before copying the current context to the target context, check whether
the register is local to this context and should not be forwarded. */
static inline bool
aarch64_frame_local_register(long reg)
{
return (reg == AARCH64_DWARF_REGNUM_RA_STATE);
}
/* Do AArch64 private extraction on ADDR_WORD based on context info CONTEXT and
unwind frame info FS. If ADDR_WORD is signed, we do address authentication
on it using CFA of current frame.

5
libgcc/unwind-dw2.c
View file

@ -1423,6 +1423,11 @@ uw_install_context_1 (struct _Unwind_Context *current,
void *c = (void *) (_Unwind_Internal_Ptr) current->reg[i];
void *t = (void *) (_Unwind_Internal_Ptr)target->reg[i];
#ifdef MD_FRAME_LOCAL_REGISTER_P
if (MD_FRAME_LOCAL_REGISTER_P (i))
continue;
#endif
gcc_assert (current->by_value[i] == 0);
if (target->by_value[i] && c)
{