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| author |   Al Viro <viro@ZenIV.linux.org.uk> | 2013-09-01 20:35:01 +0100 |
|---|---|---|
| committer |   H. Peter Anvin <hpa@linux.intel.com> | 2013-09-01 14:16:33 -0700 |
| commit | bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5 (patch) | |
| tree | 1ccdf876f778bd986a6238d379ee9e9981ed98dc /include/linux/compat.h | |
| parent | x86, smap: Handle csum_partial_copy_*_user() (diff) | |
| download | linux-dev-bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5.tar.xz linux-dev-bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5.zip | |
Introduce [compat_]save_altstack_ex() to unbreak x86 SMAP
For performance reasons, when SMAP is in use, SMAP is left open for an
entire put_user_try { ... } put_user_catch(); block, however, calling
__put_user() in the middle of that block will close SMAP as the
STAC..CLAC constructs intentionally do not nest.
Furthermore, using __put_user() rather than put_user_ex() here is bad
for performance.
Thus, introduce new [compat_]save_altstack_ex() helpers that replace
__[compat_]save_altstack() for x86, being currently the only
architecture which supports put_user_try { ... } put_user_catch().
Reported-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.8+
Link: http://lkml.kernel.org/n/tip-es5p6y64if71k8p5u08agv9n@git.kernel.org
Diffstat (limited to 'include/linux/compat.h')
| -rw-r--r-- | include/linux/compat.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/compat.h b/include/linux/compat.h index 7f0c1dd09079..ec1aee4aec9c 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -669,6 +669,13 @@ asmlinkage long compat_sys_sigaltstack(const compat_stack_t __user *uss_ptr, int compat_restore_altstack(const compat_stack_t __user *uss); int __compat_save_altstack(compat_stack_t __user *, unsigned long); +#define compat_save_altstack_ex(uss, sp) do { \ + compat_stack_t __user *__uss = uss; \ + struct task_struct *t = current; \ + put_user_ex(ptr_to_compat((void __user *)t->sas_ss_sp), &__uss->ss_sp); \ + put_user_ex(sas_ss_flags(sp), &__uss->ss_flags); \ + put_user_ex(t->sas_ss_size, &__uss->ss_size); \ +} while (0); asmlinkage long compat_sys_sched_rr_get_interval(compat_pid_t pid, struct compat_timespec __user *interval); |