diff options
Diffstat (limited to 'nptl/allocatestack.c')
| -rw-r--r-- | nptl/allocatestack.c | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c index 6d1bcaa294..8766debde5 100644 --- a/nptl/allocatestack.c +++ b/nptl/allocatestack.c @@ -356,7 +356,7 @@ setup_stack_prot (char *mem, size_t size, char *guard, size_t guardsize, const int prot) { char *guardend = guard + guardsize; -#if _STACK_GROWS_DOWN +#if _STACK_GROWS_DOWN && !defined(NEED_SEPARATE_REGISTER_STACK) /* As defined at guard_position, for architectures with downward stack the guard page is always at start of the allocated area. */ if (__mprotect (guardend, size - guardsize, prot) != 0) @@ -372,6 +372,33 @@ setup_stack_prot (char *mem, size_t size, char *guard, size_t guardsize, return 0; } +/* Mark the memory of the stack as usable to the kernel. It frees everything + except for the space used for the TCB itself. */ +static inline void +__always_inline +advise_stack_range (void *mem, size_t size, uintptr_t pd, size_t guardsize) +{ + uintptr_t sp = (uintptr_t) CURRENT_STACK_FRAME; + size_t pagesize_m1 = __getpagesize () - 1; +#if _STACK_GROWS_DOWN && !defined(NEED_SEPARATE_REGISTER_STACK) + size_t freesize = (sp - (uintptr_t) mem) & ~pagesize_m1; + assert (freesize < size); + if (freesize > PTHREAD_STACK_MIN) + __madvise (mem, freesize - PTHREAD_STACK_MIN, MADV_DONTNEED); +#else + /* Page aligned start of memory to free (higher than or equal + to current sp plus the minimum stack size). */ + uintptr_t freeblock = (sp + PTHREAD_STACK_MIN + pagesize_m1) & ~pagesize_m1; + uintptr_t free_end = (pd - guardsize) & ~pagesize_m1; + if (free_end > freeblock) + { + size_t freesize = free_end - freeblock; + assert (freesize < size); + __madvise ((void*) freeblock, freesize, MADV_DONTNEED); + } +#endif +} + /* Returns a usable stack for a new thread either by allocating a new stack or reusing a cached stack of sufficient size. ATTR must be non-NULL and point to a valid pthread_attr. |