kernel/arch/mips/include/asm/ftrace.h, branch linux-rolling-stable

mips: Replace ASSEMBLY with ASSEMBLER in the mips headers

2025-08-29T20:34:29Z

While the GCC and Clang compilers already define __ASSEMBLER__ automatically when compiling assembler code, __ASSEMBLY__ is a macro that only gets defined by the Makefiles in the kernel. Defining such a macro was necessary in the early days of the kernel, since GCC only started providing __ASSEMBLER__ since version 3.0 in 2000 (see https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=f8f769ea4e69 ). However, having two macros can be very confusing nowadays for the developers when switching between userspace and kernelspace coding, or when dealing with uapi headers that should use __ASSEMBLER__ instead. So let's now standardize on the __ASSEMBLER__ macro that is provided by the compilers. This is almost a completely mechanical patch (done with a simple "sed -i" statement), with just one comment tweaked manually in arch/mips/include/asm/cpu.h (that was missing some underscores). Cc: Thomas Bogendoerfer Cc: linux-mips@vger.kernel.org Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Maciej W. Rozycki Signed-off-by: Thomas Huth Signed-off-by: Thomas Bogendoerfer

MIPS: Use arch specific syscall name match function

2025-02-21T16:46:30Z

On MIPS system, most of the syscall function name begin with prefix sys_. Some syscalls are special such as clone/fork, function name of these begin with __sys_. Since scratch registers need be saved in stack when these system calls happens. With ftrace system call method, system call functions are declared with SYSCALL_DEFINEx, metadata of the system call symbol name begins with sys_. Here mips specific function arch_syscall_match_sym_name is used to compare function name between sys_call_table[] and metadata of syscall symbol. Signed-off-by: Bibo Mao Signed-off-by: Thomas Bogendoerfer

arch: add missing prepare_ftrace_return() prototypes

2023-11-23T10:32:32Z

The prototype for prepare_ftrace_return() is architecture specific and can't be in a global header. Since it's normally called from assembly, it doesn't really need a prototype, but we get a warning if it's missing: arch/csky/kernel/ftrace.c:147:6: error: no previous prototype for 'prepare_ftrace_return' [-Werror=missing-prototypes] arch/microblaze/kernel/ftrace.c:22:6: error: no previous prototype for 'prepare_ftrace_return' [-Werror=missing-prototypes] arch/mips/kernel/ftrace.c:305:6: error: no previous prototype for 'prepare_ftrace_return' [-Werror=missing-prototypes] Add the prototypes for the three architectures that don't already have one in asm/ftrace.h. Signed-off-by: Arnd Bergmann

MIPS: Fix build error due to PTR used in more places

2022-01-27T08:04:19Z

Use PTR_WD instead of PTR to avoid clashes with other parts. Signed-off-by: Thomas Bogendoerfer

MIPS: ftrace: Fix a microMIPS build problem

2014-10-24T00:38:33Z

Code before the .fixup section needs to have the .insn directive. This has no side effects on MIPS32/64 but it affects the way microMIPS loads the address for the return label. Fixes the following build problem: mips-linux-gnu-ld: arch/mips/built-in.o: .fixup+0x4a0: Unsupported jump between ISA modes; consider recompiling with interlinking enabled. mips-linux-gnu-ld: final link failed: Bad value Makefile:819: recipe for target 'vmlinux' failed The fix is similar to 1658f914ff91c3bf ("MIPS: microMIPS: Disable LL/SC and fix linker bug.") Signed-off-by: Markos Chandras Cc: stable@vger.kernel.org Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/8117/ Signed-off-by: Ralf Baechle

MIPS: ftrace: Tweak safe_load()/safe_store() macros

2014-03-19T22:18:40Z

Due to name collision in ftrace safe_load and safe_store macros, these macros cannot take expressions as operands. For example, compiler will complain for a macro call like the following: safe_store_code(new_code2, ip + 4, faulted); arch/mips/include/asm/ftrace.h:61:6: note: in definition of macro 'safe_store' : [dst] "r" (dst), [src] "r" (src)\ ^ arch/mips/kernel/ftrace.c:118:2: note: in expansion of macro 'safe_store_code' safe_store_code(new_code2, ip + 4, faulted); ^ arch/mips/kernel/ftrace.c:118:32: error: undefined named operand 'ip + 4' safe_store_code(new_code2, ip + 4, faulted); ^ arch/mips/include/asm/ftrace.h:61:6: note: in definition of macro 'safe_store' : [dst] "r" (dst), [src] "r" (src)\ ^ arch/mips/kernel/ftrace.c:118:2: note: in expansion of macro 'safe_store_code' safe_store_code(new_code2, ip + 4, faulted); ^ This build error is triggered by a4671094 [MIPS: ftrace: Fix icache flush range error]. Tweak variable naming in those macros to allow flexible operands. Signed-off-by: Viller Hsiao Cc: linux-mips@linux-mips.org Cc: rostedt@goodmis.org Cc: fweisbec@gmail.com Cc: mingo@redhat.com Cc: Qais.Yousef@imgtec.com Patchwork: https://patchwork.linux-mips.org/patch/6622/ 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 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 tracer support

2009-12-17T01:57:23Z

With dynamic function tracer, by default, _mcount is defined as an "empty" function, it returns directly without any more action . When enabling it in user-space, it will jump to a real tracing function(ftrace_caller), and do the real job for us. Differ from the static function tracer, dynamic function tracer provides two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the tracing of some indicated kernel functions(set_ftrace_filter). In the -v4 version, the implementation of this support is basically the same as X86 version does: _mcount is implemented as an empty function and ftrace_caller is implemented as a real tracing function respectively. But in this version, to support module tracing with the help of -mlong-calls in arch/mips/Makefile: MODFLAGS += -mlong-calls. The stuff becomes a little more complex. We need to cope with two different type of calling to _mcount. For the kernel part, the calling to _mcount(result of "objdump -hdr vmlinux"). is like this: 108: 03e0082d move at,ra 10c: 0c000000 jal 0 10c: R_MIPS_26 _mcount 10c: R_MIPS_NONE *ABS* 10c: R_MIPS_NONE *ABS* 110: 00020021 nop For the module with -mlong-calls, it looks like this: c: 3c030000 lui v1,0x0 c: R_MIPS_HI16 _mcount c: R_MIPS_NONE *ABS* c: R_MIPS_NONE *ABS* 10: 64630000 daddiu v1,v1,0 10: R_MIPS_LO16 _mcount 10: R_MIPS_NONE *ABS* 10: R_MIPS_NONE *ABS* 14: 03e0082d move at,ra 18: 0060f809 jalr v1 In the kernel version, there is only one "_mcount" string for every kernel function, so, we just need to match this one in mcount_regex of scripts/recordmcount.pl, but in the module version, we need to choose one of the two to match. Herein, I choose the first one with "R_MIPS_HI16 _mcount". and In the kernel verion, without module tracing support, we just need to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and filter the tracing of some kernel functions via replacing it by a nop instruction. but as we have described before, the instruction "jal ftrace_caller" only left 32bit length for the address of ftrace_caller, it will fail when calling from the module space. so, herein, we must replace something else. the basic idea is loading the address of ftrace_caller to v1 via changing these two instructions: lui v1,0x0 addiu v1,v1,0 If we want to enable the tracing, we need to replace the above instructions to: lui v1, HI_16BIT_ftrace_caller addiu v1, v1, LOW_16BIT_ftrace_caller If we want to stop the tracing of the indicated kernel functions, we just need to replace the "jalr v1" to a nop instruction. but we need to replace two instructions and encode the above two instructions oursevles. Is there a simpler solution? Yes! Here it is, in this version, we put _mcount and ftrace_caller together, which means the address of _mcount and ftrace_caller is the same: _mcount: ftrace_caller: j ftrace_stub nop ...(do real tracing here)... ftrace_stub: jr ra move ra, at By default, the kernel functions call _mcount, and then jump to ftrace_stub and return. and when we want to do real tracing, we just need to remove that "j ftrace_stub", and it will run through the two "nop" instructions and then do the real tracing job. what about filtering job? we just need to do this: lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004) addiu v1, v1, low_16bit_of_mcount move at, ra jalr v1 nop 1f: (rec->ip + 12) In linux-mips64, there will be some local symbols, whose name are prefixed by $L, which need to be filtered. thanks goes to Steven for writing the mips64-specific function_regex. In a conclusion, with RISC, things becomes easier with such a "stupid" trick, RISC is something like K.I.S.S, and also, there are lots of "simple" tricks in the whole ftrace support, thanks goes to Steven and the other folks for providing such a wonderful tracing framework! Signed-off-by: Wu Zhangjin 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/675/ Acked-by: Steven Rostedt Signed-off-by: Ralf Baechle

MIPS: Tracing: Add static function tracer support for MIPS

2009-12-17T01:57:21Z

If -pg of gcc is enabled with CONFIG_FUNCTION_TRACER=y. a calling to _mcount will be inserted into each kernel function. so, there is a possibility to trace the kernel functions in _mcount. This patch add the MIPS specific _mcount support for static function tracing. by default, ftrace_trace_function is initialized as ftrace_stub(an empty function), so, the default _mcount will introduce very little overhead. after enabling ftrace in user-space, it will jump to a real tracing function and do static function tracing for us. and -ffunction-sections is incompatible with -pg, so, disable it when ftracer is enabled. Signed-off-by: Wu Zhangjin Reviewed-by: 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/672/ Signed-off-by: Ralf Baechle