diff options
| author | Alan Kao <alankao@andestech.com> | 2018-02-13 13:13:17 +0800 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@sifive.com> | 2018-04-02 19:59:12 -0700 |
| commit | c15ac4fd60d5ffdb151bb2c7805f377fd7f90363 (patch) | |
| tree | 758628a4b5779f5af742da0b1781e8a467736827 /arch/riscv/kernel/mcount-dyn.S | |
| parent | a1d2a6b4cee858a2f27eebce731fbf1dfd72cb4e (diff) | |
riscv/ftrace: Add dynamic function tracer support
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 <greentime@andestech.com>
Signed-off-by: Alan Kao <alankao@andestech.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Diffstat (limited to 'arch/riscv/kernel/mcount-dyn.S')
| -rw-r--r-- | arch/riscv/kernel/mcount-dyn.S | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S new file mode 100644 index 000000000000..a3ebeadbe698 --- /dev/null +++ b/arch/riscv/kernel/mcount-dyn.S @@ -0,0 +1,50 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2017 Andes Technology Corporation */ + +#include <linux/init.h> +#include <linux/linkage.h> +#include <asm/asm.h> +#include <asm/csr.h> +#include <asm/unistd.h> +#include <asm/thread_info.h> +#include <asm/asm-offsets.h> +#include <asm-generic/export.h> +#include <asm/ftrace.h> + + .text + + .macro SAVE_ABI_STATE + addi sp, sp, -16 + sd s0, 0(sp) + sd ra, 8(sp) + addi s0, sp, 16 + .endm + + .macro RESTORE_ABI_STATE + ld ra, 8(sp) + ld s0, 0(sp) + addi sp, sp, 16 + .endm + +ENTRY(ftrace_caller) + /* + * a0: the address in the caller when calling ftrace_caller + * a1: the caller's return address + */ + ld a1, -8(s0) + addi a0, ra, -MCOUNT_INSN_SIZE + SAVE_ABI_STATE +ftrace_call: + .global ftrace_call + /* + * For the dynamic ftrace to work, here we should reserve at least + * 8 bytes for a functional auipc-jalr pair. The following call + * serves this purpose. + * + * Calling ftrace_update_ftrace_func would overwrite the nops below. + * Check ftrace_modify_all_code for details. + */ + call ftrace_stub + RESTORE_ABI_STATE + ret +ENDPROC(ftrace_caller) |