14327c6628
BSYM() was invented to allow us to work around a problem with the assembler, where local symbols resolved by the assembler for the 'adr' instruction did not take account of their ISA. Since we don't want BSYM() used elsewhere, replace BSYM() with a new macro 'badr', which is like the 'adr' pseudo-op, but with the BSYM() mechanics integrated into it. This ensures that the BSYM()-ification is only used in conjunction with 'adr'. Acked-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
244 lines
5.3 KiB
ArmAsm
244 lines
5.3 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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* Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
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*
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* bl mcount
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*
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* These versions have the limitation that in order for the mcount routine to
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* be able to determine the function's caller's address, an APCS-style frame
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* pointer (which is set up with something like the code below) is required.
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*
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* mov ip, sp
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* push {fp, ip, lr, pc}
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* sub fp, ip, #4
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*
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* With EABI, these frame pointers are not available unless -mapcs-frame is
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* specified, and if building as Thumb-2, not even then.
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*
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* Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
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* with call 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 "mov r0, r0"
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* for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
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* arch/arm/kernel/ftrace.c).
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*/
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#ifndef CONFIG_OLD_MCOUNT
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#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
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#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
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#endif
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#endif
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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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.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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.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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#ifdef CONFIG_OLD_MCOUNT
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/*
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* mcount
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*/
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.macro mcount_enter
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stmdb sp!, {r0-r3, lr}
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.endm
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.macro mcount_get_lr reg
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ldr \reg, [fp, #-4]
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.endm
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.macro mcount_exit
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ldr lr, [fp, #-4]
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ldmia sp!, {r0-r3, pc}
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.endm
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ENTRY(mcount)
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#ifdef CONFIG_DYNAMIC_FTRACE
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stmdb sp!, {lr}
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ldr lr, [fp, #-4]
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ldmia sp!, {pc}
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#else
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__mcount _old
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#endif
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ENDPROC(mcount)
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#ifdef CONFIG_DYNAMIC_FTRACE
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ENTRY(ftrace_caller_old)
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__ftrace_caller _old
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ENDPROC(ftrace_caller_old)
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#endif
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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ENTRY(ftrace_graph_caller_old)
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__ftrace_graph_caller
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ENDPROC(ftrace_graph_caller_old)
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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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#endif
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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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#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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#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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