linux/arch/arm/mm/abort-ev6.S
Will Deacon f0c4b8d653 ARM: 7396/1: errata: only handle ARM erratum #326103 on affected cores
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>
2012-04-23 14:21:52 +01:00

48 lines
1.3 KiB
ArmAsm

#include <linux/linkage.h>
#include <asm/assembler.h>
#include "abort-macro.S"
/*
* Function: v6_early_abort
*
* Params : r2 = pt_regs
* : r4 = aborted context pc
* : r5 = aborted context psr
*
* Returns : r4 - r11, r13 preserved
*
* Purpose : obtain information about current aborted instruction.
* Note: we read user space. This means we might cause a data
* abort here if the I-TLB and D-TLB aren't seeing the same
* picture. Unfortunately, this does happen. We live with it.
*/
.align 5
ENTRY(v6_early_abort)
#ifdef CONFIG_CPU_V6
sub r1, sp, #4 @ Get unused stack location
strex r0, r1, [r1] @ Clear the exclusive monitor
#elif defined(CONFIG_CPU_32v6K)
clrex
#endif
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.
*/
#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
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
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