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| author | Daniel Thompson <daniel.thompson@linaro.org> | 2015-01-09 18:30:13 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-01-12 20:26:57 +0100 |
| commit | a18f36453e0788d2d285a62b85c7c668ec119a64 (patch) | |
| tree | 58a7608414858d990b7fd969a4b3171f65f2b7e0 /arch/arm | |
| parent | ARM: 8275/1: mm: fix PMD_SECT_RDONLY undeclared compile error (diff) | |
| download | linux-a18f36453e0788d2d285a62b85c7c668ec119a64.tar.xz linux-a18f36453e0788d2d285a62b85c7c668ec119a64.zip | |
ARM: 8266/1: Remove early stack deallocation from restore_user_regs
Currently restore_user_regs deallocates the SVC stack early in
its execution and relies on no exception being taken between
the deallocation and the registers being restored. The introduction
of a default FIQ handler that also uses the SVC stack breaks this
assumption and can result in corrupted register state.
This patch works around the problem by removing the early
stack deallocation and using r2 as a temporary instead. I have
not found a way to do this without introducing an extra mov
instruction to the macro.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/kernel/entry-header.S | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 4176df721bf0..1a0045abead7 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -253,21 +253,22 @@ .endm .macro restore_user_regs, fast = 0, offset = 0 - ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr - ldr lr, [sp, #\offset + S_PC]! @ get pc + mov r2, sp + ldr r1, [r2, #\offset + S_PSR] @ get calling cpsr + ldr lr, [r2, #\offset + S_PC]! @ get pc msr spsr_cxsf, r1 @ save in spsr_svc #if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K) @ We must avoid clrex due to Cortex-A15 erratum #830321 - strex r1, r2, [sp] @ clear the exclusive monitor + strex r1, r2, [r2] @ clear the exclusive monitor #endif .if \fast - ldmdb sp, {r1 - lr}^ @ get calling r1 - lr + ldmdb r2, {r1 - lr}^ @ get calling r1 - lr .else - ldmdb sp, {r0 - lr}^ @ get calling r0 - lr + ldmdb r2, {r0 - lr}^ @ get calling r0 - lr .endif mov r0, r0 @ ARMv5T and earlier require a nop @ after ldm {}^ - add sp, sp, #S_FRAME_SIZE - S_PC + add sp, sp, #\offset + S_FRAME_SIZE movs pc, lr @ return & move spsr_svc into cpsr .endm |