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| author | Rich Felker <dalias@aerifal.cx> | 2018-10-17 22:28:51 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2018-10-17 22:28:51 -0400 |
| commit | 7136836e14e5286afe74a354c289601375bd472d (patch) | |
| tree | e97e94acd8098038229e0ccccb410352c93a941f | |
| parent | 4390383b32250a941ec616e8bff6f568a801b1c0 (diff) | |
| download | musl-7136836e14e5286afe74a354c289601375bd472d.tar.gz | |
document and make explicit desired noinline property for __init_libc
on multiple occasions I've started to flatten/inline the code in
__init_libc, only to rediscover the reason it was not inlined: GCC
fails to deallocate its stack (and now, with the changes in commit
4390383b32250a941ec616e8bff6f568a801b1c0, fails to produce a tail call
to the stage 2 function; see PR #87639) before calling main if it was
inlined.
document this with a comment and use an explicit noinline attribute if
__GNUC__ is defined so that even with CFLAGS that heavily favor
inlining it won't get inlined.
| -rw-r--r-- | src/env/__libc_start_main.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/env/__libc_start_main.c b/src/env/__libc_start_main.c index ba4d2135..2e5f9dcb 100644 --- a/src/env/__libc_start_main.c +++ b/src/env/__libc_start_main.c @@ -17,6 +17,9 @@ weak_alias(dummy1, __init_ssp); #define AUX_CNT 38 +#ifdef __GNUC__ +__attribute__((__noinline__)) +#endif void __init_libc(char **envp, char *pn) { size_t i, *auxv, aux[AUX_CNT] = { 0 }; @@ -69,6 +72,9 @@ int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv) { char **envp = argv+argc+1; + /* External linkage, and explicit noinline attribute if available, + * are used to prevent the stack frame used during init from + * persisting for the entire process lifetime. */ __init_libc(envp, argv[0]); /* Barrier against hoisting application code or anything using ssp |