diff options
Diffstat (limited to 'arch/arm/kernel/entry-header.S')
| -rw-r--r-- | arch/arm/kernel/entry-header.S | 76 |
1 files changed, 62 insertions, 14 deletions
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 7b729394e78a..4176df721bf0 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -216,26 +216,49 @@ #endif .endif msr spsr_cxsf, \rpsr -#if defined(CONFIG_CPU_V6) - ldr r0, [sp] - strex r1, r2, [sp] @ clear the exclusive monitor - ldmib sp, {r1 - pc}^ @ load r1 - pc, cpsr -#elif defined(CONFIG_CPU_32v6K) - clrex @ clear the exclusive monitor - ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr -#else - ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr +#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K) + @ We must avoid clrex due to Cortex-A15 erratum #830321 + sub r0, sp, #4 @ uninhabited address + strex r1, r2, [r0] @ clear the exclusive monitor #endif + ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr + .endm + + @ + @ svc_exit_via_fiq - like svc_exit but switches to FIQ mode before exit + @ + @ This macro acts in a similar manner to svc_exit but switches to FIQ + @ mode to restore the final part of the register state. + @ + @ We cannot use the normal svc_exit procedure because that would + @ clobber spsr_svc (FIQ could be delivered during the first few + @ instructions of vector_swi meaning its contents have not been + @ saved anywhere). + @ + @ Note that, unlike svc_exit, this macro also does not allow a caller + @ supplied rpsr. This is because the FIQ exceptions are not re-entrant + @ and the handlers cannot call into the scheduler (meaning the value + @ on the stack remains correct). + @ + .macro svc_exit_via_fiq + mov r0, sp + ldmib r0, {r1 - r14} @ abort is deadly from here onward (it will + @ clobber state restored below) + msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT + add r8, r0, #S_PC + ldr r9, [r0, #S_PSR] + msr spsr_cxsf, r9 + ldr r0, [r0, #S_R0] + ldmia r8, {pc}^ .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 msr spsr_cxsf, r1 @ save in spsr_svc -#if defined(CONFIG_CPU_V6) +#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 -#elif defined(CONFIG_CPU_32v6K) - clrex @ clear the exclusive monitor #endif .if \fast ldmdb sp, {r1 - lr}^ @ get calling r1 - lr @@ -269,7 +292,10 @@ .endif ldr lr, [sp, #S_SP] @ top of the stack ldrd r0, r1, [sp, #S_LR] @ calling lr and pc - clrex @ clear the exclusive monitor + + @ We must avoid clrex due to Cortex-A15 erratum #830321 + strex r2, r1, [sp, #S_LR] @ clear the exclusive monitor + stmdb lr!, {r0, r1, \rpsr} @ calling lr and rfe context ldmia sp, {r0 - r12} mov sp, lr @@ -277,6 +303,25 @@ rfeia sp! .endm + @ + @ svc_exit_via_fiq - like svc_exit but switches to FIQ mode before exit + @ + @ For full details see non-Thumb implementation above. + @ + .macro svc_exit_via_fiq + add r0, sp, #S_R2 + ldr lr, [sp, #S_LR] + ldr sp, [sp, #S_SP] @ abort is deadly from here onward (it will + @ clobber state restored below) + ldmia r0, {r2 - r12} + mov r1, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT + msr cpsr_c, r1 + sub r0, #S_R2 + add r8, r0, #S_PC + ldmia r0, {r0 - r1} + rfeia r8 + .endm + #ifdef CONFIG_CPU_V7M /* * Note we don't need to do clrex here as clearing the local monitor is @@ -290,13 +335,16 @@ .endm #else /* ifdef CONFIG_CPU_V7M */ .macro restore_user_regs, fast = 0, offset = 0 - clrex @ clear the exclusive monitor mov r2, sp load_user_sp_lr r2, r3, \offset + S_SP @ calling sp, lr ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr ldr lr, [sp, #\offset + S_PC] @ get pc add sp, sp, #\offset + S_SP msr spsr_cxsf, r1 @ save in spsr_svc + + @ We must avoid clrex due to Cortex-A15 erratum #830321 + strex r1, r2, [sp] @ clear the exclusive monitor + .if \fast ldmdb sp, {r1 - r12} @ get calling r1 - r12 .else |