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d3c6161956
Commit cafa0010cd ("Raise the minimum required gcc version to 4.6")
raised the minimum GCC version to 4.6. Old mcount is only required for
GCC versions older than 4.4.0. Hence old mcount support can be dropped
too.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
277 lines
6.2 KiB
ArmAsm
277 lines
6.2 KiB
ArmAsm
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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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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