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| author | Rich Felker <dalias@aerifal.cx> | 2011-02-16 09:49:54 -0500 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2011-02-16 09:49:54 -0500 |
| commit | 22cd9cae819a0fd432da4b1d21502a242871e5d9 (patch) | |
| tree | 39aaffd5e4fb3feacb755ad4d5a02c0bb096dc28 | |
| parent | bad481266e8744f8c4241e577f06e8cabf6f7f89 (diff) | |
| download | musl-22cd9cae819a0fd432da4b1d21502a242871e5d9.tar.gz | |
patch from njk: make x86_64 __uniclone branchless.
| -rw-r--r-- | src/thread/x86_64/clone.s | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/src/thread/x86_64/clone.s b/src/thread/x86_64/clone.s index 51410051..3cefd933 100644 --- a/src/thread/x86_64/clone.s +++ b/src/thread/x86_64/clone.s @@ -4,6 +4,7 @@ .type __uniclone,%function /* rdi = child_stack, rsi = start, rdx = pthread_struct */ __uniclone: + subq $8,%rsp /* pad parent stack to prevent branch later */ subq $16,%rdi /* grow child_stack */ mov %rsi,8(%rdi) /* push start onto child_stack as return ptr */ mov %rdx,0(%rdi) /* push pthread_struct onto child_stack */ @@ -13,10 +14,9 @@ __uniclone: movl $56,%eax /* clone syscall number */ movl $0x7d0f00,%edi /* rdi = flags */ mov %r10,%rdx /* rdx = parent_id */ - syscall /* clone(flags, child_stack, parent_id, - * child_id, tls) */ - test %rax,%rax - jnz 1f /* if we're in the parent -> goto 1f */ - pop %rdi /* restore pthread_struct from child stack */ -1: ret + syscall /* clone(flags, child_stack, parent_id, + * child_id, tls) */ + pop %rdi /* child stack: restore pthread_struct + * parent stack: undo rsp displacement */ + ret .size __uniclone,.-__uniclone |