diff options
Diffstat (limited to 'arch/riscv/kernel/mcount.S')
-rw-r--r-- | arch/riscv/kernel/mcount.S | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/arch/riscv/kernel/mcount.S b/arch/riscv/kernel/mcount.S new file mode 100644 index 0000000..c46a778 --- /dev/null +++ b/arch/riscv/kernel/mcount.S @@ -0,0 +1,126 @@ +/* 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 + + /* + * The call to ftrace_return_to_handler would overwrite the return + * register if a0 was not saved. + */ + .macro SAVE_RET_ABI_STATE + addi sp, sp, -32 + sd s0, 16(sp) + sd ra, 24(sp) + sd a0, 8(sp) + addi s0, sp, 32 + .endm + + .macro STORE_ABI_STATE + ld ra, 8(sp) + ld s0, 0(sp) + addi sp, sp, 16 + .endm + + .macro STORE_RET_ABI_STATE + ld ra, 24(sp) + ld s0, 16(sp) + ld a0, 8(sp) + addi sp, sp, 32 + .endm + +ENTRY(ftrace_stub) + ret +ENDPROC(ftrace_stub) + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +ENTRY(return_to_handler) +/* + * On implementing the frame point test, the ideal way is to compare the + * s0 (frame pointer, if enabled) on entry and the sp (stack pointer) on return. + * However, the psABI of variable-length-argument functions does not allow this. + * + * So alternatively we check the *old* frame pointer position, that is, the + * value stored in -16(s0) on entry, and the s0 on return. + */ +#ifdef HAVE_FUNCTION_GRAPH_FP_TEST + mv t6, s0 +#endif + SAVE_RET_ABI_STATE +#ifdef HAVE_FUNCTION_GRAPH_FP_TEST + mv a0, t6 +#endif + la t0, ftrace_return_to_handler + jalr t0 + mv a1, a0 + STORE_RET_ABI_STATE + jalr a1 +ENDPROC(return_to_handler) +EXPORT_SYMBOL(return_to_handler) +#endif + +ENTRY(_mcount) + la t4, ftrace_stub +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + la t0, ftrace_graph_return + ld t1, 0(t0) + bne t1, t4, do_ftrace_graph_caller + + la t3, ftrace_graph_entry + ld t2, 0(t3) + la t6, ftrace_graph_entry_stub + bne t2, t6, do_ftrace_graph_caller +#endif + la t3, ftrace_trace_function + ld t5, 0(t3) + bne t5, t4, do_trace + ret + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +/* + * A pseudo representation for the function graph tracer: + * prepare_to_return(&ra_to_caller_of_caller, ra_to_caller) + */ +do_ftrace_graph_caller: + addi a0, s0, -8 + mv a1, ra +#ifdef HAVE_FUNCTION_GRAPH_FP_TEST + ld a2, -16(s0) +#endif + SAVE_ABI_STATE + la t0, prepare_ftrace_return + jalr t0 + STORE_ABI_STATE + ret +#endif + +/* + * A pseudo representation for the function tracer: + * (*ftrace_trace_function)(ra_to_caller, ra_to_caller_of_caller) + */ +do_trace: + ld a1, -8(s0) + mv a0, ra + + SAVE_ABI_STATE + jalr t5 + STORE_ABI_STATE + ret +ENDPROC(_mcount) +EXPORT_SYMBOL(_mcount) |