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ARM: 7396/1: errata: only handle ARM erratum #326103 on affected cores

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Erratum #326103 ("FSR write bit incorrect on a SWP to read-only memory")
only affects the ARM 1136 core prior to r1p0. The workaround
disassembles the faulting instruction to determine whether it was a read
or write access on all v6 cores.

An issue has been reported on the ARM 11MPCore whereby loading the
faulting instruction may happen in parallel with that page being
unmapped, resulting in a deadlock due to the lack of TLB broadcasting
in hardware:

http://lists.infradead.org/pipermail/linux-arm-kernel/2012-March/091561.html

This patch limits the workaround so that it is only used on affected
cores, which are known to be UP only. Other v6 cores can rely on the
FSR to indicate the access type correctly.

Cc: stable@vger.kernel.org
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Will Deacon 2012-04-20 17:20:08 +01:00 committed by Russell King
parent e895bd7992
commit f0c4b8d653
2 changed files with 21 additions and 7 deletions
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9
arch/arm/Kconfig
View File

@ -1186,6 +1186,15 @@ if !MMU
source "arch/arm/Kconfig-nommu"
endif
config ARM_ERRATA_326103
bool "ARM errata: FSR write bit incorrect on a SWP to read-only memory"
depends on CPU_V6
help
Executing a SWP instruction to read-only memory does not set bit 11
of the FSR on the ARM 1136 prior to r1p0. This causes the kernel to
treat the access as a read, preventing a COW from occurring and
causing the faulting task to livelock.
config ARM_ERRATA_411920
bool "ARM errata: Invalidation of the Instruction Cache operation can fail"
depends on CPU_V6 || CPU_V6K

19
arch/arm/mm/abort-ev6.S
View File

@ -26,18 +26,23 @@ ENTRY(v6_early_abort)
mrc p15, 0, r1, c5, c0, 0 @ get FSR
mrc p15, 0, r0, c6, c0, 0 @ get FAR
/*
* Faulty SWP instruction on 1136 doesn't set bit 11 in DFSR (erratum 326103).
* The test below covers all the write situations, including Java bytecodes
* Faulty SWP instruction on 1136 doesn't set bit 11 in DFSR.
*/
bic r1, r1, #1 << 11 @ clear bit 11 of FSR
tst r5, #PSR_J_BIT @ Java?
#ifdef CONFIG_ARM_ERRATA_326103
ldr ip, =0x4107b36
mrc p15, 0, r3, c0, c0, 0 @ get processor id
teq ip, r3, lsr #4 @ r0 ARM1136?
bne do_DataAbort
do_thumb_abort fsr=r1, pc=r4, psr=r5, tmp=r3
ldreq r3, [r4] @ read aborted ARM instruction
tst r5, #PSR_J_BIT @ Java?
tsteq r5, #PSR_T_BIT @ Thumb?
bne do_DataAbort
bic r1, r1, #1 << 11 @ clear bit 11 of FSR
ldr r3, [r4] @ read aborted ARM instruction
#ifdef CONFIG_CPU_ENDIAN_BE8
reveq r3, r3
rev r3, r3
#endif
do_ldrd_abort tmp=ip, insn=r3
tst r3, #1 << 20 @ L = 0 -> write
orreq r1, r1, #1 << 11 @ yes.
#endif
b do_DataAbort