/* SPDX-License-Identifier: GPL-2.0-only */
|
|
#include <asm/assembler.h>
|
#include <asm/ftrace.h>
|
#include <asm/unwind.h>
|
|
#include "entry-header.S"
|
|
/*
|
* When compiling with -pg, gcc inserts a call to the mcount routine at the
|
* 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.
|
*
|
* Newer GCCs (4.4+) solve this problem by using a version of mcount with call
|
* sites like:
|
*
|
* push {lr}
|
* bl __gnu_mcount_nc
|
*
|
* With these compilers, frame pointers are not necessary.
|
*
|
* 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.
|
*
|
* 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).
|
*/
|
|
.macro mcount_adjust_addr rd, rn
|
bic \rd, \rn, #1 @ clear the Thumb bit if present
|
sub \rd, \rd, #MCOUNT_INSN_SIZE
|
.endm
|
|
.macro __mcount suffix
|
mcount_enter
|
ldr r0, =ftrace_trace_function
|
ldr r2, [r0]
|
adr 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
|
#endif
|
|
mcount_exit
|
|
1: mcount_get_lr r1 @ lr of instrumented func
|
mcount_adjust_addr r0, lr @ instrumented function
|
badr lr, 2f
|
mov pc, r2
|
2: mcount_exit
|
.endm
|
|
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
|
|
.macro __ftrace_regs_caller
|
|
str lr, [sp, #-8]! @ store LR as PC and make space for CPSR/OLD_R0,
|
@ OLD_R0 will overwrite previous LR
|
|
ldr lr, [sp, #8] @ get previous LR
|
|
str r0, [sp, #8] @ write r0 as OLD_R0 over previous LR
|
|
str lr, [sp, #-4]! @ store previous LR as LR
|
|
add lr, sp, #16 @ move in LR the value of SP as it was
|
@ before the push {lr} of the mcount mechanism
|
|
push {r0-r11, ip, lr}
|
|
@ stack content at this point:
|
@ 0 4 48 52 56 60 64 68 72
|
@ R0 | R1 | ... | IP | SP + 4 | previous LR | LR | PSR | OLD_R0 |
|
|
mov r3, sp @ struct pt_regs*
|
|
ldr r2, =function_trace_op
|
ldr r2, [r2] @ pointer to the current
|
@ function tracing op
|
|
ldr r1, [sp, #S_LR] @ lr of instrumented func
|
|
ldr lr, [sp, #S_PC] @ get LR
|
|
mcount_adjust_addr r0, lr @ instrumented function
|
|
.globl ftrace_regs_call
|
ftrace_regs_call:
|
bl ftrace_stub
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
.globl ftrace_graph_regs_call
|
ftrace_graph_regs_call:
|
mov r0, r0
|
#endif
|
|
@ pop saved regs
|
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)
|
|
@ called from __ftrace_regs_caller
|
ldr r1, [sp, #S_PC] @ instrumented routine (func)
|
mcount_adjust_addr r1, r1
|
|
mov r2, fp @ frame pointer
|
bl prepare_ftrace_return
|
|
@ pop registers saved in ftrace_regs_caller
|
pop {r0-r11, ip, lr} @ restore r0 through r12
|
ldr lr, [sp], #4 @ restore LR
|
ldr pc, [sp], #12
|
|
.endm
|
#endif
|
#endif
|
|
.macro __ftrace_caller suffix
|
mcount_enter
|
|
mcount_get_lr r1 @ lr of instrumented func
|
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
|
@ function tracing op
|
mov r3, #0 @ regs is NULL
|
#endif
|
|
.globl ftrace_call\suffix
|
ftrace_call\suffix:
|
bl ftrace_stub
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
.globl ftrace_graph_call\suffix
|
ftrace_graph_call\suffix:
|
mov r0, r0
|
#endif
|
|
mcount_exit
|
.endm
|
|
.macro __ftrace_graph_caller
|
sub r0, fp, #4 @ &lr of instrumented routine (&parent)
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
@ called from __ftrace_caller, saved in mcount_enter
|
ldr r1, [sp, #16] @ instrumented routine (func)
|
mcount_adjust_addr r1, r1
|
#else
|
@ called from __mcount, untouched in lr
|
mcount_adjust_addr r1, lr @ instrumented routine (func)
|
#endif
|
mov r2, fp @ frame pointer
|
bl prepare_ftrace_return
|
mcount_exit
|
.endm
|
|
/*
|
* __gnu_mcount_nc
|
*/
|
|
.macro mcount_enter
|
/*
|
* This pad compensates for the push {lr} at the call site. Note that we are
|
* unable to unwind through a function which does not otherwise save its lr.
|
*/
|
UNWIND(.pad #4)
|
stmdb sp!, {r0-r3, lr}
|
UNWIND(.save {r0-r3, lr})
|
.endm
|
|
.macro mcount_get_lr reg
|
ldr \reg, [sp, #20]
|
.endm
|
|
.macro mcount_exit
|
ldmia sp!, {r0-r3}
|
ldr lr, [sp, #4]
|
ldr pc, [sp], #8
|
.endm
|
|
ENTRY(__gnu_mcount_nc)
|
UNWIND(.fnstart)
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
push {lr}
|
ldr lr, [sp, #4]
|
ldr pc, [sp], #8
|
#else
|
__mcount
|
#endif
|
UNWIND(.fnend)
|
ENDPROC(__gnu_mcount_nc)
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
ENTRY(ftrace_caller)
|
UNWIND(.fnstart)
|
__ftrace_caller
|
UNWIND(.fnend)
|
ENDPROC(ftrace_caller)
|
|
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
|
ENTRY(ftrace_regs_caller)
|
UNWIND(.fnstart)
|
__ftrace_regs_caller
|
UNWIND(.fnend)
|
ENDPROC(ftrace_regs_caller)
|
#endif
|
|
#endif
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
ENTRY(ftrace_graph_caller)
|
UNWIND(.fnstart)
|
__ftrace_graph_caller
|
UNWIND(.fnend)
|
ENDPROC(ftrace_graph_caller)
|
|
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
|
ENTRY(ftrace_graph_regs_caller)
|
UNWIND(.fnstart)
|
__ftrace_graph_regs_caller
|
UNWIND(.fnend)
|
ENDPROC(ftrace_graph_regs_caller)
|
#endif
|
#endif
|
|
.purgem mcount_enter
|
.purgem mcount_get_lr
|
.purgem mcount_exit
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
.globl return_to_handler
|
return_to_handler:
|
stmdb sp!, {r0-r3}
|
mov r0, fp @ frame pointer
|
bl ftrace_return_to_handler
|
mov lr, r0 @ r0 has real ret addr
|
ldmia sp!, {r0-r3}
|
ret lr
|
#endif
|
|
ENTRY(ftrace_stub)
|
.Lftrace_stub:
|
ret lr
|
ENDPROC(ftrace_stub)
|
