提交 09bfafac 编写于 作者: R Rabin Vincent 提交者: Russell King

ARM: 6314/1: ftrace: allow build without frame pointers on ARM

With a new enough GCC, ARM function tracing can be supported without the
need for frame pointers.  This is essential for Thumb-2 support, since
frame pointers aren't available then.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NRabin Vincent <rabin@rab.in>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
上级 7e9501fd
......@@ -27,6 +27,11 @@ config ARM_UNWIND
the performance is not affected. Currently, this feature
only works with EABI compilers. If unsure say Y.
config OLD_MCOUNT
bool
depends on FUNCTION_TRACER && FRAME_POINTER
default y
config DEBUG_USER
bool "Verbose user fault messages"
help
......
......@@ -165,6 +165,8 @@ EXPORT_SYMBOL(_find_next_bit_be);
#endif
#ifdef CONFIG_FUNCTION_TRACER
#ifdef CONFIG_OLD_MCOUNT
EXPORT_SYMBOL(mcount);
#endif
EXPORT_SYMBOL(__gnu_mcount_nc);
#endif
......@@ -128,6 +128,13 @@ ENDPROC(ret_from_fork)
* allows it to be clobbered in subroutines and doesn't use it to hold
* parameters.)
*/
#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
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(mcount)
stmdb sp!, {r0-r3, lr}
......@@ -173,6 +180,12 @@ gnu_trace:
ldmia sp!, {r0-r3, ip, lr}
mov pc, ip
#ifdef CONFIG_OLD_MCOUNT
/*
* This is under an ifdef in order to force link-time errors for people trying
* to build with !FRAME_POINTER with a GCC which doesn't use the new-style
* mcount.
*/
ENTRY(mcount)
stmdb sp!, {r0-r3, lr}
ldr r0, =ftrace_trace_function
......@@ -191,6 +204,7 @@ trace:
mov pc, r2
ldr lr, [fp, #-4] @ restore lr
ldmia sp!, {r0-r3, pc}
#endif
#endif /* CONFIG_DYNAMIC_FTRACE */
......
......@@ -121,7 +121,7 @@ if FTRACE
config FUNCTION_TRACER
bool "Kernel Function Tracer"
depends on HAVE_FUNCTION_TRACER
select FRAME_POINTER
select FRAME_POINTER if (!ARM_UNWIND)
select KALLSYMS
select GENERIC_TRACER
select CONTEXT_SWITCH_TRACER
......
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