diff options
| author | Timo Teräs <timo.teras@iki.fi> | 2010-10-22 13:58:13 +0200 |
|---|---|---|
| committer | Denys Vlasenko <dvlasenk@redhat.com> | 2010-10-22 13:58:13 +0200 |
| commit | f53db356f53686cb0e4ddb25946b8cff9e82453d (patch) | |
| tree | e9e9038e90ad491b3631c8aee4637b4306e3df7f | |
| parent | 5e8d3975e2cb45df16038e2a99c74abfb252d44a (diff) | |
libm/x86: use call instead of jump for wrappers
GCC can emit prologue/epilogue code for the functions in various
different cases:
- frame pointers
- PIC build (to load ebx for indirect calls/jumps)
- forced stack smashing protection
If we used jump in such cases, we'd corrupt the call stack and
crash.
Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
| -rw-r--r-- | libm/ldouble_wrappers.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/libm/ldouble_wrappers.c b/libm/ldouble_wrappers.c index bf7ae15f0..f78a97a05 100644 --- a/libm/ldouble_wrappers.c +++ b/libm/ldouble_wrappers.c @@ -61,6 +61,10 @@ long long func##l(long double x) \ * a long double or returning a double). So we can simply jump to func. * Using __GI_func in jump to make optimized intra-library jump. * gcc will still generate a useless "ret" after asm. Oh well... + * + * Update: we do need to use call (instead of tail jump) as gcc can create + * stack frame, and push/modify/pop ebx during PIC build. + * TODO: add conditionals to use tail jump if possible? */ # define WRAPPER1(func) \ long double func##l(long double x) \ @@ -69,7 +73,7 @@ long double func##l(long double x) \ __asm__ ( \ " fldt %1\n" \ " fstpl %1\n" \ - " jmp " __stringify(__GI_##func) "\n" \ + " call " __stringify(__GI_##func) "\n" \ : "=t" (st_top) \ : "m" (x) \ ); \ @@ -82,7 +86,7 @@ int func##l(long double x) \ __asm__ ( \ " fldt %1\n" \ " fstpl %1\n" \ - " jmp " __stringify(__GI_##func) "\n" \ + " call " __stringify(__GI_##func) "\n" \ : "=a" (ret) \ : "m" (x) \ ); \ @@ -95,7 +99,7 @@ long func##l(long double x) \ __asm__ ( \ " fldt %1\n" \ " fstpl %1\n" \ - " jmp " __stringify(__GI_##func) "\n" \ + " call " __stringify(__GI_##func) "\n" \ : "=a" (ret) \ : "m" (x) \ ); \ @@ -108,7 +112,7 @@ long long func##l(long double x) \ __asm__ ( \ " fldt %1\n" \ " fstpl %1\n" \ - " jmp " __stringify(__GI_##func) "\n" \ + " call " __stringify(__GI_##func) "\n" \ : "=A" (ret) \ : "m" (x) \ ); \ |