linux-dev/arch/riscv/kernel/mcount.S, branch linus/master

riscv: Workaround mcount name prior to clang-13

2021-04-26T15:25:01Z

Prior to clang 13.0.0, the RISC-V name for the mcount symbol was "mcount", which differs from the GCC version of "_mcount", which results in the following errors: riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_level': main.c:(.text+0xe): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_start': main.c:(.text+0x4e): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_finish': main.c:(.text+0x92): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `.LBB32_28': main.c:(.text+0x30c): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `free_initmem': main.c:(.text+0x54c): undefined reference to `mcount' This has been corrected in https://reviews.llvm.org/D98881 but the minimum supported clang version is 10.0.1. To avoid build errors and to gain a working function tracer, adjust the name of the mcount symbol for older versions of clang in mount.S and recordmcount.pl. Link: https://github.com/ClangBuiltLinux/linux/issues/1331 Signed-off-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Signed-off-by: Palmer Dabbelt

RISC-V: remove the unused return_to_handler export

2018-10-23T00:38:12Z

This export is not only not needed, but also breaks symbol versioning due to being an undeclared assembly export. Signed-off-by: Christoph Hellwig Signed-off-by: Palmer Dabbelt

riscv/ftrace: Export _mcount when DYNAMIC_FTRACE isn't set

2018-06-11T16:04:03Z

The EXPORT_SYMBOL(_mcount) for RISC-V ended up inside a CONFIG_DYNAMIC_FTRACE ifdef. If you enable modules without enabling CONFIG_DYNAMIC_FTRACE then you'll get a build error without this patch because the modules won't be able to find _mcount. The new behavior is to export _mcount whenever CONFIG_FUNCTION_TRACER is defined. This matches what every other architecture is doing. Signed-off-by: Alan Kao Cc: Greentime Hu Cc: Zong Li Signed-off-by: Palmer Dabbelt

riscv/ftrace: Add dynamic function tracer support

2018-04-03T02:59:12Z

We now have dynamic ftrace with the following added items: * ftrace_make_call, ftrace_make_nop (in kernel/ftrace.c) The two functions turn each recorded call site of filtered functions into a call to ftrace_caller or nops * ftracce_update_ftrace_func (in kernel/ftrace.c) turns the nops at ftrace_call into a call to a generic entry for function tracers. * ftrace_caller (in kernel/mcount-dyn.S) The entry where each _mcount call sites calls to once they are filtered to be traced. Also, this patch fixes the semantic problems in mcount.S, which will be treated as only a reference implementation once we have the dynamic ftrace. Cc: Greentime Hu Signed-off-by: Alan Kao Signed-off-by: Palmer Dabbelt

riscv/ftrace: Add basic support

2018-01-31T03:10:54Z

This patch contains basic ftrace support for RV64I platform. Specifically, function tracer (HAVE_FUNCTION_TRACER), function graph tracer (HAVE_FUNCTION_GRAPH_TRACER), and a frame pointer test (HAVE_FUNCTION_GRAPH_FP_TEST) are implemented following the instructions in Documentation/trace/ftrace-design.txt. Note that the functions in both ftrace.c and setup.c should not be hooked with the compiler's -pg option: to prevent infinite self- referencing for the former, and to ignore early setup stuff for the latter. Signed-off-by: Alan Kao Signed-off-by: Palmer Dabbelt