ia64: Fix thread stack allocation permission set (BZ #21672)

  This patch fixes ia64 failures on thread exit by madvise the required
area taking in consideration its disjoing stacks
(NEED_SEPARATE_REGISTER_STACK).  Also the snippet that setup the
madvise call to advertise kernel the area won't be used anymore in
near future is reallocated in allocatestack.c (for consistency to
put all stack management function in one place).

Checked on x86_64-linux-gnu and i686-linux-gnu for sanity (since
it is not expected code changes for architecture that do not
define NEED_SEPARATE_REGISTER_STACK) and also got a report that
it fixes ia64-linux-gnu failures from Sergei Trofimovich
<slyfox@gentoo.org>.

	[BZ #21672]
	* nptl/allocatestack.c [_STACK_GROWS_DOWN] (setup_stack_prot):
	Set to use !NEED_SEPARATE_REGISTER_STACK as well.
	(advise_stack_range): New function.
	* nptl/pthread_create.c (START_THREAD_DEFN): Move logic to mark
	stack non required to advise_stack_range at allocatestack.c
---
 ChangeLog             |  9 +++++++++
 nptl/allocatestack.c  | 29 ++++++++++++++++++++++++++++-
 nptl/pthread_create.c | 27 ++-------------------------
 3 files changed, 39 insertions(+), 26 deletions(-)
  

On 08/29/2017 09:34 AM, Adhemerval Zanella wrote:
> This patch fixes ia64 failures on thread exit by madvise the required
> area taking in consideration its disjoing stacks
> (NEED_SEPARATE_REGISTER_STACK).  Also the snippet that setup the
> madvise call to advertise kernel the area won't be used anymore in
> near future is reallocated in allocatestack.c (for consistency to
> put all stack management function in one place).
> 
> Checked on x86_64-linux-gnu and i686-linux-gnu for sanity (since
> it is not expected code changes for architecture that do not
> define NEED_SEPARATE_REGISTER_STACK) and also got a report that
> it fixes ia64-linux-gnu failures from Sergei Trofimovich
> <slyfox@gentoo.org>.
> 
> 	[BZ #21672]
> 	* nptl/allocatestack.c [_STACK_GROWS_DOWN] (setup_stack_prot):
> 	Set to use !NEED_SEPARATE_REGISTER_STACK as well.
> 	(advise_stack_range): New function.
> 	* nptl/pthread_create.c (START_THREAD_DEFN): Move logic to mark
> 	stack non required to advise_stack_range at allocatestack.c

Looks good to me.

> ---
>  ChangeLog             |  9 +++++++++
>  nptl/allocatestack.c  | 29 ++++++++++++++++++++++++++++-
>  nptl/pthread_create.c | 27 ++-------------------------
>  3 files changed, 39 insertions(+), 26 deletions(-)
> 
> diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
> index 6d1bcaa..8766deb 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.
> diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
> index 2f8ada3..83b88bf 100644
> --- a/nptl/pthread_create.c
> +++ b/nptl/pthread_create.c
> @@ -551,31 +551,8 @@ START_THREAD_DEFN
>      }
>  #endif
>  
> -  /* Mark the memory of the stack as usable to the kernel.  We free
> -     everything except for the space used for the TCB itself.  */
> -  size_t pagesize_m1 = __getpagesize () - 1;
> -#ifdef _STACK_GROWS_DOWN
> -  char *sp = CURRENT_STACK_FRAME;
> -  size_t freesize = (sp - (char *) pd->stackblock) & ~pagesize_m1;
> -  assert (freesize < pd->stackblock_size);
> -  if (freesize > PTHREAD_STACK_MIN)
> -    __madvise (pd->stackblock, 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).  */
> -  void *freeblock = (void*)((size_t)(CURRENT_STACK_FRAME
> -				     + PTHREAD_STACK_MIN
> -				     + pagesize_m1)
> -				    & ~pagesize_m1);
> -  char *free_end = (char *) (((uintptr_t) pd - pd->guardsize) & ~pagesize_m1);
> -  /* Is there any space to free?  */
> -  if (free_end > (char *)freeblock)
> -    {
> -      size_t freesize = (size_t)(free_end - (char *)freeblock);
> -      assert (freesize < pd->stackblock_size);
> -      __madvise (freeblock, freesize, MADV_DONTNEED);
> -    }
> -#endif
> +  advise_stack_range (pd->stackblock, pd->stackblock_size, (uintptr_t) pd,
> +		      pd->guardsize);
>  
>    /* If the thread is detached free the TCB.  */
>    if (IS_DETACHED (pd))
>