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| author | Will Deacon <will.deacon@arm.com> | 2015-10-15 15:55:53 +0300 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-10-28 20:06:35 +0300 |
| commit | 589cb22bbedacf325951014c07a35a2b01ca57f6 (patch) | |
| tree | 00adb17d6a4a89a8e6ff6c4479979f80171d3119 /arch | |
| parent | 32b88194f71d6ae7768a29f87fbba454728273ee (diff) | |
| download | linux-589cb22bbedacf325951014c07a35a2b01ca57f6.tar.xz | |
arm64: compat: fix stxr failure case in SWP emulation
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.
Cc: <stable@vger.kernel.org>
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kernel/armv8_deprecated.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index bcee7abac68e..937f5e58a4d3 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -284,21 +284,23 @@ static void register_insn_emulation_sysctl(struct ctl_table *table) __asm__ __volatile__( \ ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ CONFIG_ARM64_PAN) \ - " 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" \ + " .quad 0b, 4b\n" \ + " .quad 1b, 4b\n" \ " .popsection\n" \ ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \ CONFIG_ARM64_PAN) \ |