diff options
Diffstat (limited to 'arch/arm/kernel/entry-ftrace.S')
| -rw-r--r-- | arch/arm/kernel/entry-ftrace.S | 51 |
1 files changed, 22 insertions, 29 deletions
diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S index a74289ebc803..5f1b1ce10473 100644 --- a/arch/arm/kernel/entry-ftrace.S +++ b/arch/arm/kernel/entry-ftrace.S @@ -22,10 +22,7 @@ * mcount can be thought of as a function called in the middle of a subroutine * call. As such, it needs to be transparent for both the caller and the * callee: the original lr needs to be restored when leaving mcount, and no - * registers should be clobbered. (In the __gnu_mcount_nc implementation, we - * clobber the ip register. This is OK because the ARM calling convention - * allows it to be clobbered in subroutines and doesn't use it to hold - * parameters.) + * registers should be clobbered. * * When using dynamic ftrace, we patch out the mcount call by a "pop {lr}" * instead of the __gnu_mcount_nc call (see arch/arm/kernel/ftrace.c). @@ -70,26 +67,25 @@ .macro __ftrace_regs_caller - sub sp, sp, #8 @ space for PC and CPSR OLD_R0, + str lr, [sp, #-8]! @ store LR as PC and make space for CPSR/OLD_R0, @ OLD_R0 will overwrite previous LR - add ip, sp, #12 @ move in IP the value of SP as it was - @ before the push {lr} of the mcount mechanism + ldr lr, [sp, #8] @ get previous LR - str lr, [sp, #0] @ store LR instead of PC + str r0, [sp, #8] @ write r0 as OLD_R0 over previous LR - ldr lr, [sp, #8] @ get previous LR + str lr, [sp, #-4]! @ store previous LR as LR - str r0, [sp, #8] @ write r0 as OLD_R0 over previous LR + add lr, sp, #16 @ move in LR the value of SP as it was + @ before the push {lr} of the mcount mechanism - stmdb sp!, {ip, lr} - stmdb sp!, {r0-r11, lr} + push {r0-r11, ip, lr} @ stack content at this point: @ 0 4 48 52 56 60 64 68 72 - @ R0 | R1 | ... | LR | SP + 4 | previous LR | LR | PSR | OLD_R0 | + @ R0 | R1 | ... | IP | SP + 4 | previous LR | LR | PSR | OLD_R0 | - mov r3, sp @ struct pt_regs* + mov r3, sp @ struct pt_regs* ldr r2, =function_trace_op ldr r2, [r2] @ pointer to the current @@ -112,11 +108,9 @@ ftrace_graph_regs_call: #endif @ pop saved regs - ldmia sp!, {r0-r12} @ restore r0 through r12 - ldr ip, [sp, #8] @ restore PC - ldr lr, [sp, #4] @ restore LR - ldr sp, [sp, #0] @ restore SP - mov pc, ip @ return + pop {r0-r11, ip, lr} @ restore r0 through r12 + ldr lr, [sp], #4 @ restore LR + ldr pc, [sp], #12 .endm #ifdef CONFIG_FUNCTION_GRAPH_TRACER @@ -132,11 +126,9 @@ ftrace_graph_regs_call: bl prepare_ftrace_return @ pop registers saved in ftrace_regs_caller - ldmia sp!, {r0-r12} @ restore r0 through r12 - ldr ip, [sp, #8] @ restore PC - ldr lr, [sp, #4] @ restore LR - ldr sp, [sp, #0] @ restore SP - mov pc, ip @ return + pop {r0-r11, ip, lr} @ restore r0 through r12 + ldr lr, [sp], #4 @ restore LR + ldr pc, [sp], #12 .endm #endif @@ -202,16 +194,17 @@ ftrace_graph_call\suffix: .endm .macro mcount_exit - ldmia sp!, {r0-r3, ip, lr} - ret ip + ldmia sp!, {r0-r3} + ldr lr, [sp, #4] + ldr pc, [sp], #8 .endm ENTRY(__gnu_mcount_nc) UNWIND(.fnstart) #ifdef CONFIG_DYNAMIC_FTRACE - mov ip, lr - ldmia sp!, {lr} - ret ip + push {lr} + ldr lr, [sp, #4] + ldr pc, [sp], #8 #else __mcount #endif |