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272 lines
6.1 KiB
272 lines
6.1 KiB
/* SPDX-License-Identifier: GPL-2.0-only */ |
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#include <asm/assembler.h> |
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#include <asm/ftrace.h> |
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#include <asm/unwind.h> |
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#include "entry-header.S" |
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/* |
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* When compiling with -pg, gcc inserts a call to the mcount routine at the |
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* start of every function. In mcount, apart from the function's address (in |
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* lr), we need to get hold of the function's caller's address. |
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* |
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* Newer GCCs (4.4+) solve this problem by using a version of mcount with call |
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* sites like: |
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* |
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* push {lr} |
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* bl __gnu_mcount_nc |
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* |
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* With these compilers, frame pointers are not necessary. |
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* |
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* mcount can be thought of as a function called in the middle of a subroutine |
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* call. As such, it needs to be transparent for both the caller and the |
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* callee: the original lr needs to be restored when leaving mcount, and no |
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* registers should be clobbered. (In the __gnu_mcount_nc implementation, we |
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* clobber the ip register. This is OK because the ARM calling convention |
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* allows it to be clobbered in subroutines and doesn't use it to hold |
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* parameters.) |
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* |
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* When using dynamic ftrace, we patch out the mcount call by a "pop {lr}" |
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* instead of the __gnu_mcount_nc call (see arch/arm/kernel/ftrace.c). |
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*/ |
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.macro mcount_adjust_addr rd, rn |
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bic \rd, \rn, #1 @ clear the Thumb bit if present |
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sub \rd, \rd, #MCOUNT_INSN_SIZE |
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.endm |
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.macro __mcount suffix |
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mcount_enter |
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ldr r0, =ftrace_trace_function |
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ldr r2, [r0] |
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adr r0, .Lftrace_stub |
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cmp r0, r2 |
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bne 1f |
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
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ldr r1, =ftrace_graph_return |
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ldr r2, [r1] |
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cmp r0, r2 |
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bne ftrace_graph_caller\suffix |
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ldr r1, =ftrace_graph_entry |
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ldr r2, [r1] |
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ldr r0, =ftrace_graph_entry_stub |
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cmp r0, r2 |
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bne ftrace_graph_caller\suffix |
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#endif |
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mcount_exit |
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1: mcount_get_lr r1 @ lr of instrumented func |
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mcount_adjust_addr r0, lr @ instrumented function |
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badr lr, 2f |
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mov pc, r2 |
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2: mcount_exit |
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.endm |
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS |
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.macro __ftrace_regs_caller |
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sub sp, sp, #8 @ space for PC and CPSR OLD_R0, |
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@ OLD_R0 will overwrite previous LR |
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add ip, sp, #12 @ move in IP the value of SP as it was |
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@ before the push {lr} of the mcount mechanism |
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str lr, [sp, #0] @ store LR instead of PC |
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ldr lr, [sp, #8] @ get previous LR |
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str r0, [sp, #8] @ write r0 as OLD_R0 over previous LR |
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stmdb sp!, {ip, lr} |
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stmdb sp!, {r0-r11, lr} |
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@ stack content at this point: |
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@ 0 4 48 52 56 60 64 68 72 |
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@ R0 | R1 | ... | LR | SP + 4 | previous LR | LR | PSR | OLD_R0 | |
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mov r3, sp @ struct pt_regs* |
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ldr r2, =function_trace_op |
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ldr r2, [r2] @ pointer to the current |
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@ function tracing op |
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ldr r1, [sp, #S_LR] @ lr of instrumented func |
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ldr lr, [sp, #S_PC] @ get LR |
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mcount_adjust_addr r0, lr @ instrumented function |
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.globl ftrace_regs_call |
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ftrace_regs_call: |
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bl ftrace_stub |
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
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.globl ftrace_graph_regs_call |
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ftrace_graph_regs_call: |
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mov r0, r0 |
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#endif |
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@ pop saved regs |
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ldmia sp!, {r0-r12} @ restore r0 through r12 |
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ldr ip, [sp, #8] @ restore PC |
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ldr lr, [sp, #4] @ restore LR |
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ldr sp, [sp, #0] @ restore SP |
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mov pc, ip @ return |
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.endm |
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
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.macro __ftrace_graph_regs_caller |
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sub r0, fp, #4 @ lr of instrumented routine (parent) |
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@ called from __ftrace_regs_caller |
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ldr r1, [sp, #S_PC] @ instrumented routine (func) |
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mcount_adjust_addr r1, r1 |
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mov r2, fp @ frame pointer |
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bl prepare_ftrace_return |
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@ pop registers saved in ftrace_regs_caller |
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ldmia sp!, {r0-r12} @ restore r0 through r12 |
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ldr ip, [sp, #8] @ restore PC |
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ldr lr, [sp, #4] @ restore LR |
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ldr sp, [sp, #0] @ restore SP |
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mov pc, ip @ return |
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.endm |
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#endif |
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#endif |
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.macro __ftrace_caller suffix |
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mcount_enter |
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mcount_get_lr r1 @ lr of instrumented func |
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mcount_adjust_addr r0, lr @ instrumented function |
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS |
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ldr r2, =function_trace_op |
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ldr r2, [r2] @ pointer to the current |
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@ function tracing op |
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mov r3, #0 @ regs is NULL |
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#endif |
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.globl ftrace_call\suffix |
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ftrace_call\suffix: |
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bl ftrace_stub |
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
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.globl ftrace_graph_call\suffix |
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ftrace_graph_call\suffix: |
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mov r0, r0 |
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#endif |
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mcount_exit |
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.endm |
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.macro __ftrace_graph_caller |
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sub r0, fp, #4 @ &lr of instrumented routine (&parent) |
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#ifdef CONFIG_DYNAMIC_FTRACE |
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@ called from __ftrace_caller, saved in mcount_enter |
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ldr r1, [sp, #16] @ instrumented routine (func) |
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mcount_adjust_addr r1, r1 |
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#else |
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@ called from __mcount, untouched in lr |
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mcount_adjust_addr r1, lr @ instrumented routine (func) |
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#endif |
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mov r2, fp @ frame pointer |
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bl prepare_ftrace_return |
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mcount_exit |
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.endm |
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/* |
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* __gnu_mcount_nc |
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*/ |
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.macro mcount_enter |
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/* |
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* This pad compensates for the push {lr} at the call site. Note that we are |
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* unable to unwind through a function which does not otherwise save its lr. |
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*/ |
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UNWIND(.pad #4) |
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stmdb sp!, {r0-r3, lr} |
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UNWIND(.save {r0-r3, lr}) |
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.endm |
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.macro mcount_get_lr reg |
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ldr \reg, [sp, #20] |
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.endm |
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.macro mcount_exit |
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ldmia sp!, {r0-r3, ip, lr} |
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ret ip |
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.endm |
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ENTRY(__gnu_mcount_nc) |
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UNWIND(.fnstart) |
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#ifdef CONFIG_DYNAMIC_FTRACE |
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mov ip, lr |
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ldmia sp!, {lr} |
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ret ip |
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#else |
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__mcount |
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#endif |
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UNWIND(.fnend) |
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ENDPROC(__gnu_mcount_nc) |
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#ifdef CONFIG_DYNAMIC_FTRACE |
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ENTRY(ftrace_caller) |
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UNWIND(.fnstart) |
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__ftrace_caller |
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UNWIND(.fnend) |
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ENDPROC(ftrace_caller) |
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS |
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ENTRY(ftrace_regs_caller) |
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UNWIND(.fnstart) |
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__ftrace_regs_caller |
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UNWIND(.fnend) |
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ENDPROC(ftrace_regs_caller) |
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#endif |
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#endif |
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
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ENTRY(ftrace_graph_caller) |
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UNWIND(.fnstart) |
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__ftrace_graph_caller |
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UNWIND(.fnend) |
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ENDPROC(ftrace_graph_caller) |
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS |
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ENTRY(ftrace_graph_regs_caller) |
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UNWIND(.fnstart) |
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__ftrace_graph_regs_caller |
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UNWIND(.fnend) |
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ENDPROC(ftrace_graph_regs_caller) |
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#endif |
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#endif |
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.purgem mcount_enter |
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.purgem mcount_get_lr |
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.purgem mcount_exit |
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
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.globl return_to_handler |
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return_to_handler: |
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stmdb sp!, {r0-r3} |
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mov r0, fp @ frame pointer |
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bl ftrace_return_to_handler |
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mov lr, r0 @ r0 has real ret addr |
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ldmia sp!, {r0-r3} |
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ret lr |
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#endif |
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ENTRY(ftrace_stub) |
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.Lftrace_stub: |
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ret lr |
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ENDPROC(ftrace_stub)
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