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| author | Dave Hansen <dave.hansen@linux.intel.com> | 2015-06-07 20:37:04 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-06-09 12:24:33 +0200 |
| commit | a1149fc83a1f97612e72ec24a0bdbabff7b85e77 (patch) | |
| tree | 6bc1db6d8c3cbf20c3b3fe30de585a41a7180c2e /arch/x86/mm | |
| parent | x86: Make is_64bit_mm() widely available (diff) | |
| download | linux-a1149fc83a1f97612e72ec24a0bdbabff7b85e77.tar.xz linux-a1149fc83a1f97612e72ec24a0bdbabff7b85e77.zip | |
x86/mpx: Add temporary variable to reduce masking
When we allocate a bounds table, we call mmap(), then add a
"valid" bit to the value before storing it in to the bounds
directory.
If we fail along the way, we go and mask that valid bit
_back_ out. That seems a little silly, and this makes it
much more clear when we have a plain address versus an
actual table _entry_.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183704.3D69D5F4@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/mm')
| -rw-r--r-- | arch/x86/mm/mpx.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index c17fd27579af..4f7fb7c233cc 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -429,6 +429,7 @@ static int allocate_bt(long __user *bd_entry) unsigned long expected_old_val = 0; unsigned long actual_old_val = 0; unsigned long bt_addr; + unsigned long bd_new_entry; int ret = 0; /* @@ -441,7 +442,7 @@ static int allocate_bt(long __user *bd_entry) /* * Set the valid flag (kinda like _PAGE_PRESENT in a pte) */ - bt_addr = bt_addr | MPX_BD_ENTRY_VALID_FLAG; + bd_new_entry = bt_addr | MPX_BD_ENTRY_VALID_FLAG; /* * Go poke the address of the new bounds table in to the @@ -455,7 +456,7 @@ static int allocate_bt(long __user *bd_entry) * of the MPX code that have to pagefault_disable(). */ ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry, - expected_old_val, bt_addr); + expected_old_val, bd_new_entry); if (ret) goto out_unmap; @@ -486,7 +487,7 @@ static int allocate_bt(long __user *bd_entry) trace_mpx_new_bounds_table(bt_addr); return 0; out_unmap: - vm_munmap(bt_addr & MPX_BT_ADDR_MASK, MPX_BT_SIZE_BYTES); + vm_munmap(bt_addr, MPX_BT_SIZE_BYTES); return ret; } |