Messages in this thread | | | Subject | Re: [PATCH v5 07/10] LoongArch: modules/ftrace: Initialize PLT at load time | From | Qing Zhang <> | Date | Fri, 28 Oct 2022 13:21:23 +0800 |
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Hi, Hucai
On 2022/10/28 上午11:06, Huacai Chen wrote: > Hi, Qing, > > Maybe this patch can be squashed to another one? If not, please move > it earlier because it looks like some preparation work. >
ok, I'll move this patch sequence and send it later.
- Qing
> Huacai > > On Mon, Sep 19, 2022 at 11:16 AM Qing Zhang <zhangqing@loongson.cn> wrote: >> >> To Implement ftrace trampiones through plt entry. >> >> Tested by forcing ftrace_make_call() to use the module PLT, and then >> loading up a module after setting up ftrace with: >> >> | echo ":mod:<module-name>" > set_ftrace_filter; >> | echo function > current_tracer; >> | modprobe <module-name> >> >> Since FTRACE_ADDR/FTRACE_REGS_ADDR is only defined when CONFIG_DYNAMIC_FTRACE >> is selected, we wrap its use along with most of module_init_ftrace_plt() with >> ifdeffery rather than using IS_ENABLED(). >> >> Signed-off-by: Qing Zhang <zhangqing@loongson.cn> >> --- >> arch/loongarch/include/asm/ftrace.h | 4 ++ >> arch/loongarch/include/asm/inst.h | 3 + >> arch/loongarch/include/asm/module.h | 5 +- >> arch/loongarch/include/asm/module.lds.h | 1 + >> arch/loongarch/kernel/ftrace_dyn.c | 79 +++++++++++++++++++++++++ >> arch/loongarch/kernel/inst.c | 11 ++++ >> arch/loongarch/kernel/module-sections.c | 11 ++++ >> arch/loongarch/kernel/module.c | 47 +++++++++++++++ >> 8 files changed, 160 insertions(+), 1 deletion(-) >> >> diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h >> index 5cc13ae48164..807226aad1c0 100644 >> --- a/arch/loongarch/include/asm/ftrace.h >> +++ b/arch/loongarch/include/asm/ftrace.h >> @@ -6,6 +6,10 @@ >> #ifndef _ASM_LOONGARCH_FTRACE_H >> #define _ASM_LOONGARCH_FTRACE_H >> >> +#define FTRACE_PLT_IDX 0 >> +#define FTRACE_REGS_PLT_IDX 1 >> +#define NR_FTRACE_PLTS 2 >> + >> #ifdef CONFIG_FUNCTION_TRACER >> #define MCOUNT_INSN_SIZE 4 /* sizeof mcount call */ >> >> diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h >> index f4a12f872a71..5a1aa977ae20 100644 >> --- a/arch/loongarch/include/asm/inst.h >> +++ b/arch/loongarch/include/asm/inst.h >> @@ -15,10 +15,12 @@ >> >> #define ADDR_IMMMASK_LU52ID 0xFFF0000000000000 >> #define ADDR_IMMMASK_LU32ID 0x000FFFFF00000000 >> +#define ADDR_IMMMASK_LU12IW 0x00000000FFFFF000 >> #define ADDR_IMMMASK_ADDU16ID 0x00000000FFFF0000 >> >> #define ADDR_IMMSHIFT_LU52ID 52 >> #define ADDR_IMMSHIFT_LU32ID 32 >> +#define ADDR_IMMSHIFT_LU12IW 12 >> #define ADDR_IMMSHIFT_ADDU16ID 16 >> >> #define ADDR_IMM(addr, INSN) ((addr & ADDR_IMMMASK_##INSN) >> ADDR_IMMSHIFT_##INSN) >> @@ -346,6 +348,7 @@ u32 larch_insn_gen_or(enum loongarch_gpr rd, enum loongarch_gpr rj, >> enum loongarch_gpr rk); >> u32 larch_insn_gen_move(enum loongarch_gpr rd, enum loongarch_gpr rj); >> >> +u32 larch_insn_gen_lu12iw(enum loongarch_gpr rd, int imm); >> u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm); >> u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm); >> u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned long pc, unsigned long dest); >> diff --git a/arch/loongarch/include/asm/module.h b/arch/loongarch/include/asm/module.h >> index b29b19a46f42..a311cfec2b23 100644 >> --- a/arch/loongarch/include/asm/module.h >> +++ b/arch/loongarch/include/asm/module.h >> @@ -20,6 +20,9 @@ struct mod_arch_specific { >> struct mod_section got; >> struct mod_section plt; >> struct mod_section plt_idx; >> + >> + /* for CONFIG_DYNAMIC_FTRACE */ >> + struct plt_entry *ftrace_trampolines; >> }; >> >> struct got_entry { >> @@ -49,7 +52,7 @@ static inline struct plt_entry emit_plt_entry(unsigned long val) >> { >> u32 lu12iw, lu32id, lu52id, jirl; >> >> - lu12iw = (lu12iw_op << 25 | (((val >> 12) & 0xfffff) << 5) | LOONGARCH_GPR_T1); >> + lu12iw = larch_insn_gen_lu12iw(LOONGARCH_GPR_T1, ADDR_IMM(val, LU12IW)); >> lu32id = larch_insn_gen_lu32id(LOONGARCH_GPR_T1, ADDR_IMM(val, LU32ID)); >> lu52id = larch_insn_gen_lu52id(LOONGARCH_GPR_T1, LOONGARCH_GPR_T1, ADDR_IMM(val, LU52ID)); >> jirl = larch_insn_gen_jirl(0, LOONGARCH_GPR_T1, 0, (val & 0xfff)); >> diff --git a/arch/loongarch/include/asm/module.lds.h b/arch/loongarch/include/asm/module.lds.h >> index a3d1bc0fcc72..438f09d4ccf4 100644 >> --- a/arch/loongarch/include/asm/module.lds.h >> +++ b/arch/loongarch/include/asm/module.lds.h >> @@ -5,4 +5,5 @@ SECTIONS { >> .got : { BYTE(0) } >> .plt : { BYTE(0) } >> .plt.idx : { BYTE(0) } >> + .ftrace_trampoline : { BYTE(0) } >> } >> diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c >> index f538829312d7..dd37185d446e 100644 >> --- a/arch/loongarch/kernel/ftrace_dyn.c >> +++ b/arch/loongarch/kernel/ftrace_dyn.c >> @@ -9,6 +9,7 @@ >> #include <linux/uaccess.h> >> >> #include <asm/inst.h> >> +#include <asm/module.h> >> >> static int ftrace_modify_code(unsigned long pc, u32 old, u32 new, >> bool validate) >> @@ -72,12 +73,63 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) >> return ftrace_modify_code(pc, old, new, true); >> } >> >> +static inline int __get_mod(struct module **mod, unsigned long addr) >> +{ >> + preempt_disable(); >> + *mod = __module_text_address(addr); >> + preempt_enable(); >> + >> + if (WARN_ON(!(*mod))) >> + return -EINVAL; >> + >> + return 0; >> +} >> + >> +static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr) >> +{ >> + struct plt_entry *plt = mod->arch.ftrace_trampolines; >> + >> + if (addr == FTRACE_ADDR) >> + return &plt[FTRACE_PLT_IDX]; >> + if (addr == FTRACE_REGS_ADDR && >> + IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) >> + return &plt[FTRACE_REGS_PLT_IDX]; >> + >> + return NULL; >> +} >> + >> +static unsigned long get_plt_addr(struct module *mod, unsigned long addr) >> +{ >> + struct plt_entry *plt; >> + >> + plt = get_ftrace_plt(mod, addr); >> + if (!plt) { >> + pr_err("ftrace: no module PLT for %ps\n", (void *)addr); >> + return -EINVAL; >> + } >> + >> + return (unsigned long)plt; >> +} >> + >> int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) >> { >> unsigned long pc; >> + long offset; >> u32 old, new; >> >> pc = rec->ip + LOONGARCH_INSN_SIZE; >> + offset = (long)pc - (long)addr; >> + >> + if (offset < -SZ_128M || offset >= SZ_128M) { >> + int ret; >> + struct module *mod; >> + >> + ret = __get_mod(&mod, pc); >> + if (ret) >> + return ret; >> + >> + addr = get_plt_addr(mod, addr); >> + } >> >> old = larch_insn_gen_nop(); >> new = larch_insn_gen_bl(pc, addr); >> @@ -89,9 +141,22 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, >> unsigned long addr) >> { >> unsigned long pc; >> + long offset; >> u32 old, new; >> >> pc = rec->ip + LOONGARCH_INSN_SIZE; >> + offset = (long)pc - (long)addr; >> + >> + if (offset < -SZ_128M || offset >= SZ_128M) { >> + int ret; >> + struct module *mod; >> + >> + ret = __get_mod(&mod, pc); >> + if (ret) >> + return ret; >> + >> + addr = get_plt_addr(mod, addr); >> + } >> >> new = larch_insn_gen_nop(); >> old = larch_insn_gen_bl(pc, addr); >> @@ -108,6 +173,20 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, >> u32 old, new; >> >> pc = rec->ip + LOONGARCH_INSN_SIZE; >> + offset = (long)pc - (long)addr; >> + >> + if (offset < -SZ_128M || offset >= SZ_128M) { >> + int ret; >> + struct module *mod; >> + >> + ret = __get_mod(&mod, pc); >> + if (ret) >> + return ret; >> + >> + addr = get_plt_addr(mod, addr); >> + >> + old_addr = get_plt_addr(mod, old_addr); >> + } >> >> old = larch_insn_gen_bl(pc, old_addr); >> new = larch_insn_gen_bl(pc, addr); >> diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c >> index 2d2e942eb06a..0d6bd7000ba6 100644 >> --- a/arch/loongarch/kernel/inst.c >> +++ b/arch/loongarch/kernel/inst.c >> @@ -103,6 +103,17 @@ u32 larch_insn_gen_bl(unsigned long pc, unsigned long dest) >> return insn.word; >> } >> >> +u32 larch_insn_gen_lu12iw(enum loongarch_gpr rd, int imm) >> +{ >> + union loongarch_instruction insn; >> + >> + insn.reg1i20_format.opcode = lu12iw_op; >> + insn.reg1i20_format.rd = rd; >> + insn.reg1i20_format.immediate = imm; >> + >> + return insn.word; >> +} >> + >> u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm) >> { >> union loongarch_instruction insn; >> diff --git a/arch/loongarch/kernel/module-sections.c b/arch/loongarch/kernel/module-sections.c >> index d296a70b758f..bd1a96691c98 100644 >> --- a/arch/loongarch/kernel/module-sections.c >> +++ b/arch/loongarch/kernel/module-sections.c >> @@ -4,6 +4,7 @@ >> */ >> >> #include <linux/elf.h> >> +#include <linux/ftrace.h> >> #include <linux/kernel.h> >> #include <linux/module.h> >> >> @@ -103,6 +104,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, >> char *secstrings, struct module *mod) >> { >> unsigned int i, num_plts = 0, num_gots = 0; >> + Elf_Shdr *tramp = NULL; >> >> /* >> * Find the empty .plt sections. >> @@ -114,6 +116,8 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, >> mod->arch.plt.shdr = sechdrs + i; >> else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx")) >> mod->arch.plt_idx.shdr = sechdrs + i; >> + else if (!strcmp(secstrings + sechdrs[i].sh_name, ".ftrace_trampoline")) >> + tramp = sechdrs + i; >> } >> >> if (!mod->arch.got.shdr) { >> @@ -166,5 +170,12 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, >> mod->arch.plt_idx.num_entries = 0; >> mod->arch.plt_idx.max_entries = num_plts; >> >> + if (tramp) { >> + tramp->sh_type = SHT_NOBITS; >> + tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC; >> + tramp->sh_addralign = __alignof__(struct plt_entry); >> + tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry); >> + } >> + >> return 0; >> } >> diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c >> index 097595b2fc14..e036b1ebf98e 100644 >> --- a/arch/loongarch/kernel/module.c >> +++ b/arch/loongarch/kernel/module.c >> @@ -10,6 +10,7 @@ >> >> #include <linux/moduleloader.h> >> #include <linux/elf.h> >> +#include <linux/ftrace.h> >> #include <linux/mm.h> >> #include <linux/numa.h> >> #include <linux/vmalloc.h> >> @@ -17,6 +18,7 @@ >> #include <linux/fs.h> >> #include <linux/string.h> >> #include <linux/kernel.h> >> +#include <asm/inst.h> >> >> static int rela_stack_push(s64 stack_value, s64 *rela_stack, size_t *rela_stack_top) >> { >> @@ -456,3 +458,48 @@ void *module_alloc(unsigned long size) >> return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END, >> GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, __builtin_return_address(0)); >> } >> + >> +#ifdef CONFIG_DYNAMIC_FTRACE >> +static const Elf_Shdr *find_section(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, >> + const char *name) >> +{ >> + const Elf_Shdr *s, *se; >> + const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; >> + >> + for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) { >> + if (strcmp(name, secstrs + s->sh_name) == 0) >> + return s; >> + } >> + >> + return NULL; >> +} >> +#endif >> + >> +static int module_init_ftrace_plt(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, >> + struct module *mod) >> +{ >> +#ifdef CONFIG_DYNAMIC_FTRACE >> + const Elf_Shdr *s; >> + struct plt_entry *ftrace_plts; >> + >> + s = find_section(hdr, sechdrs, ".ftrace_trampoline"); >> + if (!s) >> + return -ENOEXEC; >> + >> + ftrace_plts = (void *)s->sh_addr; >> + >> + ftrace_plts[FTRACE_PLT_IDX] = emit_plt_entry(FTRACE_ADDR); >> + >> + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) >> + ftrace_plts[FTRACE_REGS_PLT_IDX] = emit_plt_entry(FTRACE_REGS_ADDR); >> + >> + mod->arch.ftrace_trampolines = ftrace_plts; >> +#endif >> + return 0; >> +} >> + >> +int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *mod) >> +{ >> + return module_init_ftrace_plt(hdr, sechdrs, mod); >> + >> +} >> -- >> 2.36.1 >>
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