Messages in this thread Patch in this message | | | From | Qing Zhang <> | Subject | [PATCH v6 8/9] LoongArch: modules/ftrace: Initialize PLT at load time | Date | Tue, 15 Nov 2022 10:55:26 +0800 |
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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 | 22 +++++++ 8 files changed, 135 insertions(+), 1 deletion(-)
diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h index 1583ec2171fc..8d194f6da8af 100644 --- a/arch/loongarch/include/asm/ftrace.h +++ b/arch/loongarch/include/asm/ftrace.h @@ -8,6 +8,10 @@ #define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1])) +#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 0ec775d39ca5..3c13fb673f1e 100644 --- a/arch/loongarch/include/asm/inst.h +++ b/arch/loongarch/include/asm/inst.h @@ -16,10 +16,12 @@ #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) @@ -364,6 +366,7 @@ 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 cd64887e26b5..b070ce225989 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 825fcf77f9e7..a606a0cab968 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> @@ -18,6 +19,7 @@ #include <linux/string.h> #include <linux/kernel.h> #include <asm/alternative.h> +#include <asm/inst.h> static int rela_stack_push(s64 stack_value, s64 *rela_stack, size_t *rela_stack_top) { @@ -458,6 +460,24 @@ void *module_alloc(unsigned long size) GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, __builtin_return_address(0)); } +static int module_init_ftrace_plt(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, + struct module *mod) +{ +#ifdef CONFIG_DYNAMIC_FTRACE + struct plt_entry *ftrace_plts; + + ftrace_plts = (void *)sechdrs->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) { @@ -467,6 +487,8 @@ int module_finalize(const Elf_Ehdr *hdr, for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) { if (!strcmp(".altinstructions", secstrs + s->sh_name)) apply_alternatives((void *)s->sh_addr, (void *)s->sh_addr + s->sh_size); + if (!strcmp(".ftrace_trampoline", secstrs + s->sh_name)) + return module_init_ftrace_plt(hdr, s, mod); } return 0; -- 2.36.0
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