kernel.git/arch/mips/kernel/ftrace.c, branch linux-2.6.37.y

MIPS: Tracing: Cleanup of address space checking

2010-07-05T16:17:30Z

This patch adds an inline function in_module() to check which space the instruction pointer in, kernel space or module space. Note: This will not work when the kernel space and module space are the same. If they are the same, we need to modify scripts/recordmcount.pl, ftrace_make_nop/call() and the other related parts to ensure the enabling/disabling of the calling site to _mcount is right for both kernel and module. [Ralf: It also is still incorrect for some 64-bit kernels.] Signed-off-by: Wu Zhangjin Cc: linux-mips Cc: David Daney Patchwork: http://patchwork.linux-mips.org/patch/1232/ Signed-off-by: Ralf Baechle

MIPS: Tracing: Cleanup of function graph tracer

2010-07-05T16:17:30Z

Cleans up comments and ftrace_get_parent_addr() of function graph tracer. Signed-off-by: Wu Zhangjin Cc: linux-mips Cc: David Daney Patchwork: http://patchwork.linux-mips.org/patch/1231/ Signed-off-by: Ralf Baechle

MIPS: Tracing: Reduce the overhead of dynamic Function Tracer

2010-07-05T16:17:29Z

With the help of uasm this patch encodes the instructions of the dynamic function tracer in ftrace_dyn_arch_init() when initializing it. As a result we can remove the dynamic encoding of instructions in ftrace_make_nop()/call(), ftrace_enable_ftrace_graph_caller() and remove the macro jump_insn_encode() and at last this reduce the overhead of dynamic Function Tracer. This also is cleaner. Signed-off-by: Wu Zhangjin Cc: linux-mips Cc: David Daney Patchwork: http://patchwork.linux-mips.org/patch/1230/ Signed-off-by: Ralf Baechle

MIPS: Tracing: Cleanup of instructions used

2010-07-05T16:17:29Z

This patch adds some cleanups of the instructions: o use macros instead of magic numbers o use macros instead of variables to reduce some overhead o add new macro for the jal instruction Signed-off-by: Wu Zhangjin Cc: linux-mips Cc: David Daney Patchwork: http://patchwork.linux-mips.org/patch/1229/ Signed-off-by: Ralf Baechle

MIPS: Tracing: Fix 32-bit support with -mmcount-ra-address

2010-07-05T16:17:28Z

For 32-bit kernel the -mmcount-ra-address option of gcc 4.5 emits one extra instruction before calling to _mcount so we need to use a different "b 1f" for it. Signed-off-by: Wu Zhangjin Cc: linux-mips Cc: David Daney Patchwork: http://patchwork.linux-mips.org/patch/1228/ Signed-off-by: Ralf Baechle

MIPS: Loongson: Change the Email address of Wu Zhangjin

2010-02-27T11:53:12Z

Currently wuzj@lemote.com is not usable; change it to wuzhangjin@gmail.com. Signed-off-by: Wu Zhangjin Cc: linux-mips@linux-mips.org Cc: yanh@lemote.com Cc: huhb@lemote.com Cc: zhangfx@lemote.com Patchwork: http://patchwork.linux-mips.org/patch/829/ Signed-off-by: Ralf Baechle

MIPS: Tracing: Make function graph tracer work with -mmcount-ra-address

2009-12-17T01:57:27Z

That thread "MIPS: Add option to pass return address location to _mcount" from "David Daney " have added a new option -mmcount-ra-address to gcc(4.5) for MIPS to transfer the location of the return address to _mcount. Benefit from this new feature, function graph tracer on MIPS will be easier and safer to hijack the return address of the kernel function, which will save some overhead and make the whole thing more reliable. In this patch, at first, try to enable the option -mmcount-ra-address in arch/mips/Makefile with cc-option, if gcc support it, it will be enabled, otherwise, no side effect. and then, we need to support this new option of gcc 4.5 and also support the old gcc versions. with _mcount in the old gcc versions, it's not easy to get the location of return address(tracing: add function graph tracer support for MIPS), so, we do it in a C function: ftrace_get_parent_addr(ftrace.c), but with -mmcount-ra-address, only several instructions need to get what we want, so, I put into asm(mcount.S). and also, as the $12(t0) is used by -mmcount-ra-address for transferring the localtion of return address to _mcount, we need to save it into the stack and restore it when enabled dynamic function tracer, 'Cause we have called "ftrace_call" before "ftrace_graph_caller", which may destroy $12(t0). (Thanks to David for providing that -mcount-ra-address and giving the idea of KBUILD_MCOUNT_RA_ADDRESS, both of them have made the whole thing more beautiful!) Signed-off-by: Wu Zhangjin Cc: Steven Rostedt Cc: Nicholas Mc Guire Cc: zhangfx@lemote.com Cc: Wu Zhangjin Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Frederic Weisbecker Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/681/ Signed-off-by: Ralf Baechle

MIPS: Tracing: Make ftrace for MIPS work without -fno-omit-frame-pointer

2009-12-17T01:57:25Z

When remove the -fno-omit-frame-pointer, gcc will not save the frame pointer for us, we need to save one ourselves. Signed-off-by: Wu Zhangjin Cc: Steven Rostedt Cc: Nicholas Mc Guire Cc: zhangfx@lemote.com Cc: Wu Zhangjin Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Frederic Weisbecker Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/679/ Signed-off-by: Ralf Baechle

MIPS: Tracing: Add dynamic function graph tracer for MIPS

2009-12-17T01:57:25Z

This patch make function graph tracer work with dynamic function tracer. To share the source code of dynamic function tracer(MCOUNT_SAVE_REGS), and avoid restoring the whole saved registers, we need to restore the ra register from the stack. (NOTE: This not work with 32bit! need to ensure why!) Signed-off-by: Wu Zhangjin Cc: Steven Rostedt Cc: Nicholas Mc Guire Cc: zhangfx@lemote.com Cc: Wu Zhangjin Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Frederic Weisbecker Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/678/ Signed-off-by: Ralf Baechle

MIPS: Tracing: Add function graph tracer support for MIPS

2009-12-17T01:57:25Z

The implementation of function graph tracer for MIPS is a little different from X86. in MIPS, gcc(with -pg) only transfer the caller's return address(at) and the _mcount's return address(ra) to us. For the kernel part without -mlong-calls: move at, ra jal _mcount For the module part with -mlong-calls: lui v1, hi16bit_of_mcount addiu v1, v1, low16bit_of_mcount move at, ra jal _mcount Without -mlong-calls, if the function is a leaf, it will not save the return address(ra): ffffffff80101298 : ffffffff80101298: 67bdfff0 daddiu sp,sp,-16 ffffffff8010129c: ffbe0008 sd s8,8(sp) ffffffff801012a0: 03a0f02d move s8,sp ffffffff801012a4: 03e0082d move at,ra ffffffff801012a8: 0c042930 jal ffffffff8010a4c0 <_mcount> ffffffff801012ac: 00020021 nop so, we can hijack it directly in _mcount, but if the function is non-leaf, the return address is saved in the stack. ffffffff80133030 : ffffffff80133030: 67bdff50 daddiu sp,sp,-176 ffffffff80133034: ffbe00a0 sd s8,160(sp) ffffffff80133038: 03a0f02d move s8,sp ffffffff8013303c: ffbf00a8 sd ra,168(sp) ffffffff80133040: ffb70098 sd s7,152(sp) ffffffff80133044: ffb60090 sd s6,144(sp) ffffffff80133048: ffb50088 sd s5,136(sp) ffffffff8013304c: ffb40080 sd s4,128(sp) ffffffff80133050: ffb30078 sd s3,120(sp) ffffffff80133054: ffb20070 sd s2,112(sp) ffffffff80133058: ffb10068 sd s1,104(sp) ffffffff8013305c: ffb00060 sd s0,96(sp) ffffffff80133060: 03e0082d move at,ra ffffffff80133064: 0c042930 jal ffffffff8010a4c0 <_mcount> ffffffff80133068: 00020021 nop but we can not get the exact stack address(which saved ra) directly in _mcount, we need to search the content of at register in the stack space or search the "s{d,w} ra, offset(sp)" instruction in the text. 'Cause we can not prove there is only a match in the stack space, so, we search the text instead. as we can see, if the first instruction above "move at, ra" is not a store instruction, there should be a leaf function, so we hijack the at register directly via putting &return_to_handler into it, otherwise, we search the "s{d,w} ra, offset(sp)" instruction to get the stack offset, and then the stack address. we use the above copy_process() as an example, we at last find "ffbf00a8", 0xa8 is the stack offset, we plus it with s8(fp), that is the stack address, we hijack the content via writing the &return_to_handler in. If with -mlong-calls, since there are two more instructions above "move at, ra", so, we can move the pointer to the position above "lui v1, hi16bit_of_mcount". Signed-off-by: Wu Zhangjin Cc: Steven Rostedt Cc: Nicholas Mc Guire Cc: zhangfx@lemote.com Cc: Wu Zhangjin Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Frederic Weisbecker Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/677/ Signed-off-by: Ralf Baechle