diff options
Diffstat (limited to 'nptl/allocatestack.c')
| -rw-r--r-- | nptl/allocatestack.c | 34 |
1 files changed, 20 insertions, 14 deletions
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c index 800ca89..99f56b9 100644 --- a/nptl/allocatestack.c +++ b/nptl/allocatestack.c @@ -150,17 +150,11 @@ get_cached_stack (size_t *sizep, void **memp) and fallback to ALLOCATE_GUARD_PROT_NONE if the madvise call fails. */ static int allocate_stack_mode = ALLOCATE_GUARD_MADV_GUARD; -static inline int stack_prot (void) -{ - return (PROT_READ | PROT_WRITE - | ((GL(dl_stack_flags) & PF_X) ? PROT_EXEC : 0)); -} - static void * allocate_thread_stack (size_t size, size_t guardsize) { /* MADV_ADVISE_GUARD does not require an additional PROT_NONE mapping. */ - int prot = stack_prot (); + int prot = GL(dl_stack_prot_flags); if (atomic_load_relaxed (&allocate_stack_mode) == ALLOCATE_GUARD_PROT_NONE) /* If a guard page is required, avoid committing memory by first allocate @@ -216,7 +210,7 @@ setup_stack_prot (char *mem, size_t size, struct pthread *pd, } else { - const int prot = stack_prot (); + const int prot = GL(dl_stack_prot_flags); char *guardend = guard + guardsize; #if _STACK_GROWS_DOWN /* As defined at guard_position, for architectures with downward stack @@ -240,7 +234,7 @@ setup_stack_prot (char *mem, size_t size, struct pthread *pd, /* Update the guard area of the thread stack MEM of size SIZE with the new GUARDISZE. It uses the method defined by PD stack_mode. */ static inline bool -adjust_stack_prot (char *mem, size_t size, const struct pthread *pd, +adjust_stack_prot (char *mem, size_t size, struct pthread *pd, size_t guardsize, size_t pagesize_m1) { /* The required guard area is larger than the current one. For @@ -258,11 +252,23 @@ adjust_stack_prot (char *mem, size_t size, const struct pthread *pd, so use the new guard placement with the new size. */ if (guardsize > pd->guardsize) { + /* There was no need to previously setup a guard page, so we need + to check whether the kernel supports guard advise. */ char *guard = guard_position (mem, size, guardsize, pd, pagesize_m1); - if (pd->stack_mode == ALLOCATE_GUARD_MADV_GUARD) - return __madvise (guard, guardsize, MADV_GUARD_INSTALL) == 0; - else if (pd->stack_mode == ALLOCATE_GUARD_PROT_NONE) - return __mprotect (guard, guardsize, PROT_NONE) == 0; + if (atomic_load_relaxed (&allocate_stack_mode) + == ALLOCATE_GUARD_MADV_GUARD) + { + if (__madvise (guard, guardsize, MADV_GUARD_INSTALL) == 0) + { + pd->stack_mode = ALLOCATE_GUARD_MADV_GUARD; + return true; + } + atomic_store_relaxed (&allocate_stack_mode, + ALLOCATE_GUARD_PROT_NONE); + } + + pd->stack_mode = ALLOCATE_GUARD_PROT_NONE; + return __mprotect (guard, guardsize, PROT_NONE) == 0; } /* The current guard area is larger than the required one. For _STACK_GROWS_DOWN is means change the guard as: @@ -294,7 +300,7 @@ adjust_stack_prot (char *mem, size_t size, const struct pthread *pd, } else if (pd->stack_mode == ALLOCATE_GUARD_PROT_NONE) { - const int prot = stack_prot (); + const int prot = GL(dl_stack_prot_flags); #if _STACK_GROWS_DOWN return __mprotect (mem + guardsize, slacksize, prot) == 0; #else |