diff options
| author | Will Deacon <will.deacon@arm.com> | 2015-10-15 13:55:53 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-11-09 14:33:39 -0800 |
| commit | 599f528a90026dd61533aa5145e64cc0ac3625ae (patch) | |
| tree | e11e25a8bf4c16f2f9d7112c3e10f9477469c849 | |
| parent | dbf2a8c020446889a5214c3f91fd69442cd2cd86 (diff) | |
arm64: compat: fix stxr failure case in SWP emulation
commit 589cb22bbedacf325951014c07a35a2b01ca57f6 upstream.
If the STXR instruction fails in the SWP emulation code, we leave *data
overwritten with the loaded value, therefore corrupting the data written
by a subsequent, successful attempt.
This patch re-jigs the code so that we only write back to *data once we
know that the update has happened.
Fixes: bd35a4adc413 ("arm64: Port SWP/SWPB emulation support from arm")
Reported-by: Shengjiu Wang <shengjiu.wang@freescale.com>
Reported-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/arm64/kernel/armv8_deprecated.c | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index 7922c2e710ca..7ac3920b1356 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -279,22 +279,24 @@ static void register_insn_emulation_sysctl(struct ctl_table *table) */ #define __user_swpX_asm(data, addr, res, temp, B) \ __asm__ __volatile__( \ - " mov %w2, %w1\n" \ - "0: ldxr"B" %w1, [%3]\n" \ - "1: stxr"B" %w0, %w2, [%3]\n" \ + "0: ldxr"B" %w2, [%3]\n" \ + "1: stxr"B" %w0, %w1, [%3]\n" \ " cbz %w0, 2f\n" \ " mov %w0, %w4\n" \ + " b 3f\n" \ "2:\n" \ + " mov %w1, %w2\n" \ + "3:\n" \ " .pushsection .fixup,\"ax\"\n" \ " .align 2\n" \ - "3: mov %w0, %w5\n" \ - " b 2b\n" \ + "4: mov %w0, %w5\n" \ + " b 3b\n" \ " .popsection" \ " .pushsection __ex_table,\"a\"\n" \ " .align 3\n" \ - " .quad 0b, 3b\n" \ - " .quad 1b, 3b\n" \ - " .popsection" \ + " .quad 0b, 4b\n" \ + " .quad 1b, 4b\n" \ + " .popsection\n" \ : "=&r" (res), "+r" (data), "=&r" (temp) \ : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT) \ : "memory") |