diff options
Diffstat (limited to 'thread_pthread.c')
-rw-r--r-- | thread_pthread.c | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/thread_pthread.c b/thread_pthread.c index 767805119d..1acd56c357 100644 --- a/thread_pthread.c +++ b/thread_pthread.c @@ -693,17 +693,31 @@ reserve_stack(volatile char *limit, size_t size) const volatile char *end = buf + sizeof(buf); limit += size; if (limit > end) { - size = limit - end; - limit = alloca(size); - limit[stack_check_margin+size-1] = 0; + /* |<-bottom (=limit(a)) top->| + * | .. |<-buf 256B |<-end | stack check | + * | 256B | =size= | margin (4KB)| + * | =size= limit(b)->| 256B | | + * | | alloca(sz) | | | + * | .. |<-buf |<-limit(c) [sz-1]->0> | | + */ + size_t sz = limit - end; + limit = alloca(sz); + limit[sz-1] = 0; } } else { limit -= size; if (buf > limit) { - limit = alloca(buf - limit); - limit[0] = 0; /* ensure alloca is called */ - limit -= stack_check_margin; + /* |<-top (=limit(a)) bottom->| + * | .. | 256B buf->| | stack check | + * | 256B | =size= | margin (4KB)| + * | =size= limit(b)->| 256B | | + * | | alloca(sz) | | | + * | .. | buf->| limit(c)-><0> | | + */ + size_t sz = buf - limit; + limit = alloca(sz); + limit[0] = 0; } } } |