[PATCH 2/2] i386: Use __seg_gs qualifiers in {STACK, POINTER}_CHK_GUARD macros
Uros Bizjak
ubizjak@gmail.com
Tue Sep 9 16:41:54 GMT 2025
Use the __seg_gs named address space qualifiers to cast reads of
the guard values in the TCB as %gs: prefixed addresses.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: H.J.Lu <hjl.tools@gmail.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Carlos O'Donell <carlos@redhat.com>
---
sysdeps/i386/stackguard-macros.h | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/sysdeps/i386/stackguard-macros.h b/sysdeps/i386/stackguard-macros.h
index 039762927c..574a409584 100644
--- a/sysdeps/i386/stackguard-macros.h
+++ b/sysdeps/i386/stackguard-macros.h
@@ -1,12 +1,7 @@
#include <stdint.h>
#define STACK_CHK_GUARD \
- ({ uintptr_t x; asm ("movl %%gs:0x14, %0" : "=r" (x)); x; })
+ (*(uintptr_t __seg_gs *) offsetof (tcbhead_t, stack_guard))
#define POINTER_CHK_GUARD \
- ({ \
- uintptr_t x; \
- asm ("movl %%gs:%c1, %0" : "=r" (x) \
- : "i" (offsetof (tcbhead_t, pointer_guard))); \
- x; \
- })
+ (*(uintptr_t __seg_gs *) offsetof (tcbhead_t, pointer_guard))
--
2.51.0
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