[Mesa-dev] [PATCH v2] mapi: avoid text relocation in x86 tsd stubs

[Jonathan Gray]

Make similiar changes to libglvnd to avoid a text relocation in
x86 tsd stubs fixing the build with lld.

v2:
  - store the address of the GOT in ebx required before calling PLT stub
  - change .balign values to match X86_ENTRY_SIZE

Signed-off-by: Jonathan Gray <jsg at jsg.id.au>
Cc: mesa-stable at lists.freedesktop.org
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108541
---
 src/mapi/entry_x86_tsd.h | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/mapi/entry_x86_tsd.h b/src/mapi/entry_x86_tsd.h
index 0c28c8ff068..1dec3ed86c4 100644
--- a/src/mapi/entry_x86_tsd.h
+++ b/src/mapi/entry_x86_tsd.h
@@ -31,25 +31,31 @@
 #define HIDDEN
 #endif
 
-#define X86_ENTRY_SIZE 32
+#define X86_ENTRY_SIZE 64
 
 __asm__(".text\n"
-        ".balign 32\n"
+        ".balign " U_STRINGIFY(X86_ENTRY_SIZE) "\n"
         "x86_entry_start:");
 
 #define STUB_ASM_ENTRY(func)        \
    ".globl " func "\n"              \
    ".type " func ", @function\n"    \
-   ".balign 32\n"                   \
+   ".balign " U_STRINGIFY(X86_ENTRY_SIZE) "\n" \
    func ":"
 
 #define STUB_ASM_CODE(slot)         \
-   "movl " ENTRY_CURRENT_TABLE ", %eax\n\t" \
+   "push %ebx\n\t"                  \
+   "call 1f\n"                      \
+   "1:\n\t"                         \
+   "popl %ebx\n\t"                  \
+   "addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %ebx\n\t" \
+   "movl " ENTRY_CURRENT_TABLE "@GOT(%ebx), %eax\n\t" \
+   "mov (%eax), %eax\n\t"           \
    "testl %eax, %eax\n\t"           \
-   "je 1f\n\t"                      \
-   "jmp *(4 * " slot ")(%eax)\n"    \
+   "jne 1f\n\t"                     \
+   "call " ENTRY_CURRENT_TABLE_GET "@PLT\n" \
    "1:\n\t"                         \
-   "call " ENTRY_CURRENT_TABLE_GET "\n\t" \
+   "pop %ebx\n\t"                   \
    "jmp *(4 * " slot ")(%eax)"
 
 #define MAPI_TMP_STUB_ASM_GCC
@@ -57,7 +63,7 @@ __asm__(".text\n"
 
 #ifndef MAPI_MODE_BRIDGE
 
-__asm__(".balign 32\n"
+__asm__(".balign " U_STRINGIFY(X86_ENTRY_SIZE) "\n"
         "x86_entry_end:");
 
 #include <string.h>
-- 
2.19.1