Commit-ID: a1149fc83a1f97612e72ec24a0bdbabff7b85e77 Gitweb: http://git.kernel.org/tip/a1149fc83a1f97612e72ec24a0bdbabff7b85e77 Author: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> AuthorDate: Sun, 7 Jun 2015 11:37:04 -0700 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Tue, 9 Jun 2015 12:24:33 +0200 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@xxxxxxxxxxxxxxx> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Dave Hansen <dave@xxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20150607183704.3D69D5F4@xxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/mm/mpx.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index c17fd27..4f7fb7c 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; } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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