diff options
Diffstat (limited to 'arch/arm/kernel/entry-ftrace.S')
| -rw-r--r-- | arch/arm/kernel/entry-ftrace.S | 227 |
1 files changed, 93 insertions, 134 deletions
diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S index efcd9f25a14b..e24ee559af81 100644 --- a/arch/arm/kernel/entry-ftrace.S +++ b/arch/arm/kernel/entry-ftrace.S @@ -1,8 +1,4 @@ -/* - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - */ +/* SPDX-License-Identifier: GPL-2.0-only */ #include <asm/assembler.h> #include <asm/ftrace.h> @@ -15,23 +11,8 @@ * start of every function. In mcount, apart from the function's address (in * lr), we need to get hold of the function's caller's address. * - * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this: - * - * bl mcount - * - * These versions have the limitation that in order for the mcount routine to - * be able to determine the function's caller's address, an APCS-style frame - * pointer (which is set up with something like the code below) is required. - * - * mov ip, sp - * push {fp, ip, lr, pc} - * sub fp, ip, #4 - * - * With EABI, these frame pointers are not available unless -mapcs-frame is - * specified, and if building as Thumb-2, not even then. - * - * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount, - * with call sites like: + * Newer GCCs (4.4+) solve this problem by using a version of mcount with call + * sites like: * * push {lr} * bl __gnu_mcount_nc @@ -41,22 +22,12 @@ * 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 "mov r0, r0" - * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see - * arch/arm/kernel/ftrace.c). + * When using dynamic ftrace, we patch out the mcount call by a "add sp, #4" + * instead of the __gnu_mcount_nc call (see arch/arm/kernel/ftrace.c). */ -#ifndef CONFIG_OLD_MCOUNT -#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4)) -#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0. -#endif -#endif - .macro mcount_adjust_addr rd, rn bic \rd, \rn, #1 @ clear the Thumb bit if present sub \rd, \rd, #MCOUNT_INSN_SIZE @@ -64,23 +35,20 @@ .macro __mcount suffix mcount_enter - ldr r0, =ftrace_trace_function - ldr r2, [r0] - adr r0, .Lftrace_stub + ldr_va r2, ftrace_trace_function + badr r0, .Lftrace_stub cmp r0, r2 bne 1f #ifdef CONFIG_FUNCTION_GRAPH_TRACER - ldr r1, =ftrace_graph_return - ldr r2, [r1] - cmp r0, r2 - bne ftrace_graph_caller\suffix - - ldr r1, =ftrace_graph_entry - ldr r2, [r1] - ldr r0, =ftrace_graph_entry_stub - cmp r0, r2 - bne ftrace_graph_caller\suffix + ldr_va r2, ftrace_graph_return + cmp r0, r2 + bne ftrace_graph_caller\suffix + + ldr_va r2, ftrace_graph_entry + mov_l r0, ftrace_graph_entry_stub + cmp r0, r2 + bne ftrace_graph_caller\suffix #endif mcount_exit @@ -96,29 +64,27 @@ .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 + ldr_va r2, function_trace_op @ pointer to the current @ function tracing op ldr r1, [sp, #S_LR] @ lr of instrumented func @@ -134,35 +100,37 @@ ftrace_regs_call: #ifdef CONFIG_FUNCTION_GRAPH_TRACER .globl ftrace_graph_regs_call ftrace_graph_regs_call: - mov r0, r0 +ARM( mov r0, r0 ) +THUMB( nop.w ) #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 .macro __ftrace_graph_regs_caller - sub r0, fp, #4 @ lr of instrumented routine (parent) +#ifdef CONFIG_UNWINDER_FRAME_POINTER + sub r0, fp, #4 @ lr of instrumented routine (parent) +#else + add r0, sp, #S_LR +#endif @ called from __ftrace_regs_caller - ldr r1, [sp, #S_PC] @ instrumented routine (func) + ldr r1, [sp, #S_PC] @ instrumented routine (func) mcount_adjust_addr r1, r1 - mov r2, fp @ frame pointer + mov r2, fpreg @ frame pointer + add r3, sp, #PT_REGS_SIZE 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 @@ -175,8 +143,7 @@ ftrace_graph_regs_call: mcount_adjust_addr r0, lr @ instrumented function #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS - ldr r2, =function_trace_op - ldr r2, [r2] @ pointer to the current + ldr_va r2, function_trace_op @ pointer to the current @ function tracing op mov r3, #0 @ regs is NULL #endif @@ -188,14 +155,19 @@ ftrace_call\suffix: #ifdef CONFIG_FUNCTION_GRAPH_TRACER .globl ftrace_graph_call\suffix ftrace_graph_call\suffix: - mov r0, r0 +ARM( mov r0, r0 ) +THUMB( nop.w ) #endif mcount_exit .endm .macro __ftrace_graph_caller +#ifdef CONFIG_UNWINDER_FRAME_POINTER sub r0, fp, #4 @ &lr of instrumented routine (&parent) +#else + add r0, sp, #20 +#endif #ifdef CONFIG_DYNAMIC_FTRACE @ called from __ftrace_caller, saved in mcount_enter ldr r1, [sp, #16] @ instrumented routine (func) @@ -204,56 +176,12 @@ ftrace_graph_call\suffix: @ called from __mcount, untouched in lr mcount_adjust_addr r1, lr @ instrumented routine (func) #endif - mov r2, fp @ frame pointer + mov r2, fpreg @ frame pointer + add r3, sp, #24 bl prepare_ftrace_return mcount_exit .endm -#ifdef CONFIG_OLD_MCOUNT -/* - * mcount - */ - -.macro mcount_enter - stmdb sp!, {r0-r3, lr} -.endm - -.macro mcount_get_lr reg - ldr \reg, [fp, #-4] -.endm - -.macro mcount_exit - ldr lr, [fp, #-4] - ldmia sp!, {r0-r3, pc} -.endm - -ENTRY(mcount) -#ifdef CONFIG_DYNAMIC_FTRACE - stmdb sp!, {lr} - ldr lr, [fp, #-4] - ldmia sp!, {pc} -#else - __mcount _old -#endif -ENDPROC(mcount) - -#ifdef CONFIG_DYNAMIC_FTRACE -ENTRY(ftrace_caller_old) - __ftrace_caller _old -ENDPROC(ftrace_caller_old) -#endif - -#ifdef CONFIG_FUNCTION_GRAPH_TRACER -ENTRY(ftrace_graph_caller_old) - __ftrace_graph_caller -ENDPROC(ftrace_graph_caller_old) -#endif - -.purgem mcount_enter -.purgem mcount_get_lr -.purgem mcount_exit -#endif - /* * __gnu_mcount_nc */ @@ -273,16 +201,17 @@ ENDPROC(ftrace_graph_caller_old) .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 @@ -327,17 +256,47 @@ ENDPROC(ftrace_graph_regs_caller) .purgem mcount_exit #ifdef CONFIG_FUNCTION_GRAPH_TRACER - .globl return_to_handler -return_to_handler: - stmdb sp!, {r0-r3} - mov r0, fp @ frame pointer +ENTRY(return_to_handler) + mov ip, sp @ sp at exit of instrumented routine + sub sp, #PT_REGS_SIZE + str r0, [sp, #S_R0] + str r1, [sp, #S_R1] + str r2, [sp, #S_R2] + str r3, [sp, #S_R3] + str ip, [sp, #S_FP] + mov r0, sp bl ftrace_return_to_handler - mov lr, r0 @ r0 has real ret addr - ldmia sp!, {r0-r3} + mov lr, r0 @ r0 has real ret addr + ldr r3, [sp, #S_R3] + ldr r2, [sp, #S_R2] + ldr r1, [sp, #S_R1] + ldr r0, [sp, #S_R0] + add sp, sp, #PT_REGS_SIZE @ restore stack pointer ret lr +ENDPROC(return_to_handler) #endif ENTRY(ftrace_stub) .Lftrace_stub: ret lr ENDPROC(ftrace_stub) + +ENTRY(ftrace_stub_graph) + ret lr +ENDPROC(ftrace_stub_graph) + +#ifdef CONFIG_DYNAMIC_FTRACE + + __INIT + + .macro init_tramp, dst:req +ENTRY(\dst\()_from_init) + ldr pc, =\dst +ENDPROC(\dst\()_from_init) + .endm + + init_tramp ftrace_caller +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + init_tramp ftrace_regs_caller +#endif +#endif |