diff options
| -rw-r--r-- | arch/riscv/Kconfig | 1 | ||||
| -rw-r--r-- | arch/riscv/include/asm/ftrace.h | 54 | ||||
| -rw-r--r-- | arch/riscv/kernel/Makefile | 5 | ||||
| -rw-r--r-- | arch/riscv/kernel/ftrace.c | 103 | ||||
| -rw-r--r-- | arch/riscv/kernel/mcount-dyn.S | 50 | ||||
| -rw-r--r-- | arch/riscv/kernel/mcount.S | 22 |
6 files changed, 223 insertions, 12 deletions
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index c9ccc6ea4371..1e9d878c1ac4 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -115,6 +115,7 @@ config ARCH_RV64I select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FTRACE_MCOUNT_RECORD + select HAVE_DYNAMIC_FTRACE endchoice diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h index 66d4175eb13e..078743aacfd3 100644 --- a/arch/riscv/include/asm/ftrace.h +++ b/arch/riscv/include/asm/ftrace.h @@ -8,3 +8,57 @@ #if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_FRAME_POINTER) #define HAVE_FUNCTION_GRAPH_FP_TEST #endif + +#ifndef __ASSEMBLY__ +void _mcount(void); +static inline unsigned long ftrace_call_adjust(unsigned long addr) +{ + return addr; +} + +struct dyn_arch_ftrace { +}; +#endif + +#ifdef CONFIG_DYNAMIC_FTRACE +/* + * A general call in RISC-V is a pair of insts: + * 1) auipc: setting high-20 pc-related bits to ra register + * 2) jalr: setting low-12 offset to ra, jump to ra, and set ra to + * return address (original pc + 4) + * + * Dynamic ftrace generates probes to call sites, so we must deal with + * both auipc and jalr at the same time. + */ + +#define MCOUNT_ADDR ((unsigned long)_mcount) +#define JALR_SIGN_MASK (0x00000800) +#define JALR_OFFSET_MASK (0x00000fff) +#define AUIPC_OFFSET_MASK (0xfffff000) +#define AUIPC_PAD (0x00001000) +#define JALR_SHIFT 20 +#define JALR_BASIC (0x000080e7) +#define AUIPC_BASIC (0x00000097) +#define NOP4 (0x00000013) + +#define make_call(caller, callee, call) \ +do { \ + call[0] = to_auipc_insn((unsigned int)((unsigned long)callee - \ + (unsigned long)caller)); \ + call[1] = to_jalr_insn((unsigned int)((unsigned long)callee - \ + (unsigned long)caller)); \ +} while (0) + +#define to_jalr_insn(offset) \ + (((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_BASIC) + +#define to_auipc_insn(offset) \ + ((offset & JALR_SIGN_MASK) ? \ + (((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_BASIC) : \ + ((offset & AUIPC_OFFSET_MASK) | AUIPC_BASIC)) + +/* + * Let auipc+jalr be the basic *mcount unit*, so we make it 8 bytes here. + */ +#define MCOUNT_INSN_SIZE 8 +#endif diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 196f62ffc428..d7bdf888f1ca 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -34,7 +34,8 @@ CFLAGS_setup.o := -mcmodel=medany obj-$(CONFIG_SMP) += smpboot.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_MODULES) += module.o -obj-$(CONFIG_FUNCTION_TRACER) += mcount.o -obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o + +obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o +obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o clean: diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c index d0de68d144cb..be4b24332d97 100644 --- a/arch/riscv/kernel/ftrace.c +++ b/arch/riscv/kernel/ftrace.c @@ -6,9 +6,109 @@ */ #include <linux/ftrace.h> +#include <linux/uaccess.h> +#include <asm/cacheflush.h> +#ifdef CONFIG_DYNAMIC_FTRACE +static int ftrace_check_current_call(unsigned long hook_pos, + unsigned int *expected) +{ + unsigned int replaced[2]; + unsigned int nops[2] = {NOP4, NOP4}; + + /* we expect nops at the hook position */ + if (!expected) + expected = nops; + + /* + * Read the text we want to modify; + * return must be -EFAULT on read error + */ + if (probe_kernel_read(replaced, (void *)hook_pos, MCOUNT_INSN_SIZE)) + return -EFAULT; + + /* + * Make sure it is what we expect it to be; + * return must be -EINVAL on failed comparison + */ + if (memcmp(expected, replaced, sizeof(replaced))) { + pr_err("%p: expected (%08x %08x) but get (%08x %08x)", + (void *)hook_pos, expected[0], expected[1], replaced[0], + replaced[1]); + return -EINVAL; + } + + return 0; +} + +static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target, + bool enable) +{ + unsigned int call[2]; + unsigned int nops[2] = {NOP4, NOP4}; + int ret = 0; + + make_call(hook_pos, target, call); + + /* replace the auipc-jalr pair at once */ + ret = probe_kernel_write((void *)hook_pos, enable ? call : nops, + MCOUNT_INSN_SIZE); + /* return must be -EPERM on write error */ + if (ret) + return -EPERM; + + smp_mb(); + flush_icache_range((void *)hook_pos, (void *)hook_pos + MCOUNT_INSN_SIZE); + + return 0; +} + +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + int ret = ftrace_check_current_call(rec->ip, NULL); + + if (ret) + return ret; + + return __ftrace_modify_call(rec->ip, addr, true); +} + +int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, + unsigned long addr) +{ + unsigned int call[2]; + int ret; + + make_call(rec->ip, addr, call); + ret = ftrace_check_current_call(rec->ip, call); + + if (ret) + return ret; + + return __ftrace_modify_call(rec->ip, addr, false); +} + +int ftrace_update_ftrace_func(ftrace_func_t func) +{ + int ret = __ftrace_modify_call((unsigned long)&ftrace_call, + (unsigned long)func, true); + if (!ret) { + ret = __ftrace_modify_call((unsigned long)&ftrace_regs_call, + (unsigned long)func, true); + } + + return ret; +} + +int __init ftrace_dyn_arch_init(void) +{ + return 0; +} +#endif + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER /* - * Most of this file is copied from arm64. + * Most of this function is copied from arm64. */ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, unsigned long frame_pointer) @@ -39,3 +139,4 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, return; *parent = return_hooker; } +#endif 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) diff --git a/arch/riscv/kernel/mcount.S b/arch/riscv/kernel/mcount.S index c46a778627be..ce9bdc57a2a1 100644 --- a/arch/riscv/kernel/mcount.S +++ b/arch/riscv/kernel/mcount.S @@ -32,13 +32,13 @@ addi s0, sp, 32 .endm - .macro STORE_ABI_STATE + .macro RESTORE_ABI_STATE ld ra, 8(sp) ld s0, 0(sp) addi sp, sp, 16 .endm - .macro STORE_RET_ABI_STATE + .macro RESTORE_RET_ABI_STATE ld ra, 24(sp) ld s0, 16(sp) ld a0, 8(sp) @@ -46,6 +46,10 @@ .endm ENTRY(ftrace_stub) +#ifdef CONFIG_DYNAMIC_FTRACE + .global _mcount + .set _mcount, ftrace_stub +#endif ret ENDPROC(ftrace_stub) @@ -66,15 +70,15 @@ ENTRY(return_to_handler) #ifdef HAVE_FUNCTION_GRAPH_FP_TEST mv a0, t6 #endif - la t0, ftrace_return_to_handler - jalr t0 + call ftrace_return_to_handler mv a1, a0 - STORE_RET_ABI_STATE + RESTORE_RET_ABI_STATE jalr a1 ENDPROC(return_to_handler) EXPORT_SYMBOL(return_to_handler) #endif +#ifndef CONFIG_DYNAMIC_FTRACE ENTRY(_mcount) la t4, ftrace_stub #ifdef CONFIG_FUNCTION_GRAPH_TRACER @@ -104,9 +108,8 @@ do_ftrace_graph_caller: ld a2, -16(s0) #endif SAVE_ABI_STATE - la t0, prepare_ftrace_return - jalr t0 - STORE_ABI_STATE + call prepare_ftrace_return + RESTORE_ABI_STATE ret #endif @@ -120,7 +123,8 @@ do_trace: SAVE_ABI_STATE jalr t5 - STORE_ABI_STATE + RESTORE_ABI_STATE ret ENDPROC(_mcount) EXPORT_SYMBOL(_mcount) +#endif |