From: Uros Bizjak <ubizjak@gmail.com>
Date: Tue, 9 Sep 2025 16:41:53 +0000 (+0200)
Subject: x86_64: Use __seg_fs qualifiers in {STACK, POINTER}_CHK_GUARD macros
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f402c54483bd7686d95df25d072edaf0964cdabe;p=thirdparty%2Fglibc.git

x86_64: Use __seg_fs qualifiers in {STACK, POINTER}_CHK_GUARD macros

Use the __seg_fs named address space qualifiers to cast reads of
the guard values in the TCB as %fs: 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>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
---

diff --git a/sysdeps/x86_64/stackguard-macros.h b/sysdeps/x86_64/stackguard-macros.h
index 1948800cd0..1d4c620ff1 100644
--- a/sysdeps/x86_64/stackguard-macros.h
+++ b/sysdeps/x86_64/stackguard-macros.h
@@ -1,11 +1,7 @@
 #include <stdint.h>
 
 #define STACK_CHK_GUARD \
-  ({ uintptr_t x;						\
-     asm ("mov %%fs:%c1, %0" : "=r" (x)				\
-	  : "i" (offsetof (tcbhead_t, stack_guard))); x; })
+  (*(uintptr_t __seg_fs *) offsetof (tcbhead_t, stack_guard))
 
 #define POINTER_CHK_GUARD \
-  ({ uintptr_t x;						\
-     asm ("mov %%fs:%c1, %0" : "=r" (x)				\
-	  : "i" (offsetof (tcbhead_t, pointer_guard))); x; })
+  (*(uintptr_t __seg_fs *) offsetof (tcbhead_t, pointer_guard))