[PATCH 7/8] ARM: move ftrace assembly code to separate file
Russell King
rmk+kernel at arm.linux.org.uk
Mon Nov 17 12:30:15 PST 2014
The ftrace assembly code doesn't need to live in entry-common.S and
be surrounded with #ifdef CONFIG_FUNCTION_TRACER. Instead, move it
to its own file and conditionally assemble it.
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
---
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/entry-common.S | 235 ---------------------------------------
arch/arm/kernel/entry-ftrace.S | 243 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 244 insertions(+), 235 deletions(-)
create mode 100644 arch/arm/kernel/entry-ftrace.S
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 38ddd9f83d0e..738ebe5a91e6 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -47,6 +47,7 @@ endif
obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o
obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o
obj-$(CONFIG_ARM_ARCH_TIMER) += arch_timer.o
+obj-$(CONFIG_FUNCTION_TRACER) += entry-ftrace.o
obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o insn.o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o insn.o
obj-$(CONFIG_JUMP_LABEL) += jump_label.o insn.o patch.o
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 6bb09d4abdea..f8ccc21fa032 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -109,241 +109,6 @@ ENDPROC(ret_from_fork)
#undef CALL
#define CALL(x) .long x
-#ifdef CONFIG_FUNCTION_TRACER
-/*
- * 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.
- *
- * 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:
- *
- * 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. (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.)
- *
- * 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).
- */
-
-#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
-.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
- adr lr, BSYM(2f)
- mov pc, r2
-2: mcount_exit
-.endm
-
-.macro __ftrace_caller suffix
- mcount_enter
-
- mcount_get_lr r1 @ lr of instrumented func
- mcount_adjust_addr r0, lr @ instrumented function
-
- .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
-
-#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
- */
-
-.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, ip, lr}
- ret ip
-.endm
-
-ENTRY(__gnu_mcount_nc)
-UNWIND(.fnstart)
-#ifdef CONFIG_DYNAMIC_FTRACE
- mov ip, lr
- ldmia sp!, {lr}
- ret ip
-#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)
-#endif
-
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-ENTRY(ftrace_graph_caller)
-UNWIND(.fnstart)
- __ftrace_graph_caller
-UNWIND(.fnend)
-ENDPROC(ftrace_graph_caller)
-#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)
-
-#endif /* CONFIG_FUNCTION_TRACER */
-
/*=============================================================================
* SWI handler
*-----------------------------------------------------------------------------
diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S
new file mode 100644
index 000000000000..fe57c73e70a4
--- /dev/null
+++ b/arch/arm/kernel/entry-ftrace.S
@@ -0,0 +1,243 @@
+/*
+ * 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.
+ */
+
+#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.
+ *
+ * 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:
+ *
+ * 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. (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.)
+ *
+ * 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).
+ */
+
+#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
+.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
+ adr lr, BSYM(2f)
+ mov pc, r2
+2: mcount_exit
+.endm
+
+.macro __ftrace_caller suffix
+ mcount_enter
+
+ mcount_get_lr r1 @ lr of instrumented func
+ mcount_adjust_addr r0, lr @ instrumented function
+
+ .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
+
+#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
+ */
+
+.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, ip, lr}
+ ret ip
+.endm
+
+ENTRY(__gnu_mcount_nc)
+UNWIND(.fnstart)
+#ifdef CONFIG_DYNAMIC_FTRACE
+ mov ip, lr
+ ldmia sp!, {lr}
+ ret ip
+#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)
+#endif
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ENTRY(ftrace_graph_caller)
+UNWIND(.fnstart)
+ __ftrace_graph_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_graph_caller)
+#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)
--
1.8.3.1
More information about the linux-arm-kernel
mailing list