From: madvenka@linux.microsoft.com To: jpoimboe@redhat.com, peterz@infradead.org, chenzhongjin@huawei.com, mark.rutland@arm.com, broonie@kernel.org, nobuta.keiya@fujitsu.com, sjitindarsingh@gmail.com, catalin.marinas@arm.com, will@kernel.org, jamorris@linux.microsoft.com, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com Subject: [RFC PATCH v2 11/20] objtool: arm64: Walk instructions and compute CFI for each instruction Date: Mon, 23 May 2022 19:16:28 -0500 [thread overview] Message-ID: <20220524001637.1707472-12-madvenka@linux.microsoft.com> (raw) In-Reply-To: <20220524001637.1707472-1-madvenka@linux.microsoft.com> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> Implement arch_initial_func_cfi_state() to initialize the CFI for a function. Add code to fpv_decode() to walk the instructions in every function and compute the CFI information for each instruction. Implement special handling for cases like jump tables. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> --- tools/objtool/arch/arm64/decode.c | 15 +++ tools/objtool/fpv.c | 204 ++++++++++++++++++++++++++++++ 2 files changed, 219 insertions(+) diff --git a/tools/objtool/arch/arm64/decode.c b/tools/objtool/arch/arm64/decode.c index f9df8b321659..93ef7c0811f1 100644 --- a/tools/objtool/arch/arm64/decode.c +++ b/tools/objtool/arch/arm64/decode.c @@ -35,6 +35,21 @@ struct decode { /* --------------------- arch support functions ------------------------- */ +void arch_initial_func_cfi_state(struct cfi_init_state *state) +{ + int i; + + for (i = 0; i < CFI_NUM_REGS; i++) { + state->regs[i].base = CFI_UNDEFINED; + state->regs[i].offset = 0; + } + state->regs[CFI_FP].base = CFI_CFA; + + /* initial CFA (call frame address) */ + state->cfa.base = CFI_SP; + state->cfa.offset = 0; +} + unsigned long arch_dest_reloc_offset(int addend) { return addend; diff --git a/tools/objtool/fpv.c b/tools/objtool/fpv.c index 92ad0d0aac8e..52f613ae998f 100644 --- a/tools/objtool/fpv.c +++ b/tools/objtool/fpv.c @@ -13,6 +13,8 @@ #include <objtool/insn.h> #include <objtool/warn.h> +static bool fill; + /* * Find the destination instructions for all jumps. */ @@ -50,15 +52,217 @@ static void add_jump_destinations(struct objtool_file *file) } } +static void update_cfi_state(struct cfi_state *cfi, struct stack_op *op) +{ + struct cfi_reg *cfa = &cfi->cfa; + struct cfi_reg *regs = cfi->regs; + + if (op->src.reg == CFI_SP) { + if (op->dest.reg == CFI_SP) + cfa->offset -= op->src.offset; + else + regs[CFI_FP].offset = -cfa->offset + op->src.offset; + } else { + if (op->dest.reg == CFI_SP) + cfa->offset = -(regs[CFI_FP].offset + op->src.offset); + else + regs[CFI_FP].offset += op->src.offset; + } + + if (cfa->offset < -regs[CFI_FP].offset) + regs[CFI_FP].offset = 0; +} + +static void do_stack_ops(struct instruction *insn, struct insn_state *state) +{ + struct stack_op *op; + + list_for_each_entry(op, &insn->stack_ops, list) { + update_cfi_state(&state->cfi, op); + } +} + +static void walk_code(struct objtool_file *file, struct section *sec, + struct symbol *func, + struct instruction *insn, struct insn_state *state) +{ + struct symbol *insn_func = insn->func; + struct instruction *dest; + struct cfi_state save_cfi; + unsigned long start, end; + + for (; insn; insn = next_insn_same_sec(file, insn)) { + + if (insn->func != insn_func) + return; + + if (insn->cfi) { + if (fill) { + /* CFI is present. Nothing to fill. */ + return; + } + if (insn->cfi->regs[CFI_FP].offset || + !state->cfi.regs[CFI_FP].offset) { + return; + } + /* + * The new CFI contains a valid frame and the existing + * CFI doesn't. Replace the existing CFI with the new + * one. + */ + } + insn->cfi = cfi_hash_find_or_add(&state->cfi); + dest = insn->jump_dest; + + do_stack_ops(insn, state); + + switch (insn->type) { + case INSN_BUG: + case INSN_RETURN: + case INSN_UNRELIABLE: + return; + + case INSN_CALL: + case INSN_CALL_DYNAMIC: + start = func->offset; + end = start + func->len; + /* + * Treat intra-function calls as jumps and fall + * through. + */ + if (!dest || dest->sec != sec || + dest->offset <= start || dest->offset >= end) { + break; + } + /* fallthrough */ + + case INSN_JUMP_UNCONDITIONAL: + case INSN_JUMP_CONDITIONAL: + case INSN_JUMP_DYNAMIC: + if (dest) { + save_cfi = state->cfi; + walk_code(file, sec, func, dest, state); + state->cfi = save_cfi; + } + if (insn->type == INSN_JUMP_UNCONDITIONAL || + insn->type == INSN_JUMP_DYNAMIC) { + return; + } + break; + + default: + break; + } + } +} + +static void walk_function(struct objtool_file *file, struct section *sec, + struct symbol *func) +{ + struct instruction *insn = find_insn(file, sec, func->offset); + struct insn_state state; + + init_insn_state(&state, sec); + set_func_state(&state.cfi); + + walk_code(file, sec, func, insn, &state); +} + +/* + * This function addresses cases like jump tables where there is an array + * of unconditional branches. The normal walk would not have visited these + * instructions and established CFIs for them. Find those instructions. For + * each such instruction, copy the CFI from the branch instruction and + * propagate it down. + */ +static void fill_function(struct objtool_file *file, struct section *sec, + struct symbol *func) +{ + struct instruction *insn, *prev; + struct insn_state state; + + func_for_each_insn(file, func, insn) { + + if (insn->cfi) { + /* Instruction already has a CFI. */ + continue; + } + + prev = list_prev_entry(insn, list); + if (!prev || !prev->cfi) { + /* + * Previous instruction does not have a CFI that can + * be used for this instruction. + */ + continue; + } + + if (prev->type != INSN_JUMP_UNCONDITIONAL && + prev->type != INSN_JUMP_DYNAMIC) { + /* Only copy CFI from unconditional branches. */ + continue; + } + + /* + * Propagate the CFI to all the instructions that can be + * visited from the current instruction that don't already + * have a CFI. + */ + state.cfi = *prev->cfi; + walk_code(file, insn->sec, insn->func, insn, &state); + } +} + +static void walk_section(struct objtool_file *file, struct section *sec) +{ + struct symbol *func; + + list_for_each_entry(func, &sec->symbol_list, list) { + + if (func->type != STT_FUNC || !func->len || + func->pfunc != func || func->alias != func) { + /* No CFI generated for this function. */ + continue; + } + + if (!fill) + walk_function(file, sec, func); + else + fill_function(file, sec, func); + } +} + +static void walk_sections(struct objtool_file *file) +{ + struct section *sec; + + for_each_sec(file, sec) { + if (sec->sh.sh_flags & SHF_EXECINSTR) + walk_section(file, sec); + } +} + int fpv_decode(struct objtool_file *file) { int ret; + arch_initial_func_cfi_state(&initial_func_cfi); + + if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3))) + return -1; + ret = decode_instructions(file); if (ret) return ret; add_jump_destinations(file); + if (!list_empty(&file->insn_list)) { + fill = false; + walk_sections(file); + fill = true; + walk_sections(file); + } + return 0; } -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: madvenka@linux.microsoft.com To: jpoimboe@redhat.com, peterz@infradead.org, chenzhongjin@huawei.com, mark.rutland@arm.com, broonie@kernel.org, nobuta.keiya@fujitsu.com, sjitindarsingh@gmail.com, catalin.marinas@arm.com, will@kernel.org, jamorris@linux.microsoft.com, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com Subject: [RFC PATCH v2 11/20] objtool: arm64: Walk instructions and compute CFI for each instruction Date: Mon, 23 May 2022 19:16:28 -0500 [thread overview] Message-ID: <20220524001637.1707472-12-madvenka@linux.microsoft.com> (raw) In-Reply-To: <20220524001637.1707472-1-madvenka@linux.microsoft.com> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> Implement arch_initial_func_cfi_state() to initialize the CFI for a function. Add code to fpv_decode() to walk the instructions in every function and compute the CFI information for each instruction. Implement special handling for cases like jump tables. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> --- tools/objtool/arch/arm64/decode.c | 15 +++ tools/objtool/fpv.c | 204 ++++++++++++++++++++++++++++++ 2 files changed, 219 insertions(+) diff --git a/tools/objtool/arch/arm64/decode.c b/tools/objtool/arch/arm64/decode.c index f9df8b321659..93ef7c0811f1 100644 --- a/tools/objtool/arch/arm64/decode.c +++ b/tools/objtool/arch/arm64/decode.c @@ -35,6 +35,21 @@ struct decode { /* --------------------- arch support functions ------------------------- */ +void arch_initial_func_cfi_state(struct cfi_init_state *state) +{ + int i; + + for (i = 0; i < CFI_NUM_REGS; i++) { + state->regs[i].base = CFI_UNDEFINED; + state->regs[i].offset = 0; + } + state->regs[CFI_FP].base = CFI_CFA; + + /* initial CFA (call frame address) */ + state->cfa.base = CFI_SP; + state->cfa.offset = 0; +} + unsigned long arch_dest_reloc_offset(int addend) { return addend; diff --git a/tools/objtool/fpv.c b/tools/objtool/fpv.c index 92ad0d0aac8e..52f613ae998f 100644 --- a/tools/objtool/fpv.c +++ b/tools/objtool/fpv.c @@ -13,6 +13,8 @@ #include <objtool/insn.h> #include <objtool/warn.h> +static bool fill; + /* * Find the destination instructions for all jumps. */ @@ -50,15 +52,217 @@ static void add_jump_destinations(struct objtool_file *file) } } +static void update_cfi_state(struct cfi_state *cfi, struct stack_op *op) +{ + struct cfi_reg *cfa = &cfi->cfa; + struct cfi_reg *regs = cfi->regs; + + if (op->src.reg == CFI_SP) { + if (op->dest.reg == CFI_SP) + cfa->offset -= op->src.offset; + else + regs[CFI_FP].offset = -cfa->offset + op->src.offset; + } else { + if (op->dest.reg == CFI_SP) + cfa->offset = -(regs[CFI_FP].offset + op->src.offset); + else + regs[CFI_FP].offset += op->src.offset; + } + + if (cfa->offset < -regs[CFI_FP].offset) + regs[CFI_FP].offset = 0; +} + +static void do_stack_ops(struct instruction *insn, struct insn_state *state) +{ + struct stack_op *op; + + list_for_each_entry(op, &insn->stack_ops, list) { + update_cfi_state(&state->cfi, op); + } +} + +static void walk_code(struct objtool_file *file, struct section *sec, + struct symbol *func, + struct instruction *insn, struct insn_state *state) +{ + struct symbol *insn_func = insn->func; + struct instruction *dest; + struct cfi_state save_cfi; + unsigned long start, end; + + for (; insn; insn = next_insn_same_sec(file, insn)) { + + if (insn->func != insn_func) + return; + + if (insn->cfi) { + if (fill) { + /* CFI is present. Nothing to fill. */ + return; + } + if (insn->cfi->regs[CFI_FP].offset || + !state->cfi.regs[CFI_FP].offset) { + return; + } + /* + * The new CFI contains a valid frame and the existing + * CFI doesn't. Replace the existing CFI with the new + * one. + */ + } + insn->cfi = cfi_hash_find_or_add(&state->cfi); + dest = insn->jump_dest; + + do_stack_ops(insn, state); + + switch (insn->type) { + case INSN_BUG: + case INSN_RETURN: + case INSN_UNRELIABLE: + return; + + case INSN_CALL: + case INSN_CALL_DYNAMIC: + start = func->offset; + end = start + func->len; + /* + * Treat intra-function calls as jumps and fall + * through. + */ + if (!dest || dest->sec != sec || + dest->offset <= start || dest->offset >= end) { + break; + } + /* fallthrough */ + + case INSN_JUMP_UNCONDITIONAL: + case INSN_JUMP_CONDITIONAL: + case INSN_JUMP_DYNAMIC: + if (dest) { + save_cfi = state->cfi; + walk_code(file, sec, func, dest, state); + state->cfi = save_cfi; + } + if (insn->type == INSN_JUMP_UNCONDITIONAL || + insn->type == INSN_JUMP_DYNAMIC) { + return; + } + break; + + default: + break; + } + } +} + +static void walk_function(struct objtool_file *file, struct section *sec, + struct symbol *func) +{ + struct instruction *insn = find_insn(file, sec, func->offset); + struct insn_state state; + + init_insn_state(&state, sec); + set_func_state(&state.cfi); + + walk_code(file, sec, func, insn, &state); +} + +/* + * This function addresses cases like jump tables where there is an array + * of unconditional branches. The normal walk would not have visited these + * instructions and established CFIs for them. Find those instructions. For + * each such instruction, copy the CFI from the branch instruction and + * propagate it down. + */ +static void fill_function(struct objtool_file *file, struct section *sec, + struct symbol *func) +{ + struct instruction *insn, *prev; + struct insn_state state; + + func_for_each_insn(file, func, insn) { + + if (insn->cfi) { + /* Instruction already has a CFI. */ + continue; + } + + prev = list_prev_entry(insn, list); + if (!prev || !prev->cfi) { + /* + * Previous instruction does not have a CFI that can + * be used for this instruction. + */ + continue; + } + + if (prev->type != INSN_JUMP_UNCONDITIONAL && + prev->type != INSN_JUMP_DYNAMIC) { + /* Only copy CFI from unconditional branches. */ + continue; + } + + /* + * Propagate the CFI to all the instructions that can be + * visited from the current instruction that don't already + * have a CFI. + */ + state.cfi = *prev->cfi; + walk_code(file, insn->sec, insn->func, insn, &state); + } +} + +static void walk_section(struct objtool_file *file, struct section *sec) +{ + struct symbol *func; + + list_for_each_entry(func, &sec->symbol_list, list) { + + if (func->type != STT_FUNC || !func->len || + func->pfunc != func || func->alias != func) { + /* No CFI generated for this function. */ + continue; + } + + if (!fill) + walk_function(file, sec, func); + else + fill_function(file, sec, func); + } +} + +static void walk_sections(struct objtool_file *file) +{ + struct section *sec; + + for_each_sec(file, sec) { + if (sec->sh.sh_flags & SHF_EXECINSTR) + walk_section(file, sec); + } +} + int fpv_decode(struct objtool_file *file) { int ret; + arch_initial_func_cfi_state(&initial_func_cfi); + + if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3))) + return -1; + ret = decode_instructions(file); if (ret) return ret; add_jump_destinations(file); + if (!list_empty(&file->insn_list)) { + fill = false; + walk_sections(file); + fill = true; + walk_sections(file); + } + return 0; } -- 2.25.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-05-24 0:17 UTC|newest] Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <e81e773678f88f7c2ff7480e2eb096973ec198db> 2022-05-24 0:16 ` [RFC PATCH v2 00/20] arm64: livepatch: Use ORC for dynamic frame pointer validation madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 01/20] objtool: Reorganize CFI code madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 02/20] objtool: Reorganize instruction-related code madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 03/20] objtool: Move decode_instructions() to a separate file madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 04/20] objtool: Reorganize Unwind hint code madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 05/20] objtool: Reorganize ORC types madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 14:27 ` Chen Zhongjin 2022-05-24 14:27 ` Chen Zhongjin 2022-05-29 15:36 ` Madhavan T. Venkataraman 2022-05-29 15:36 ` Madhavan T. Venkataraman 2022-05-24 0:16 ` [RFC PATCH v2 06/20] objtool: Reorganize ORC code madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 07/20] objtool: Reorganize ORC kernel code madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 08/20] objtool: arm64: Implement decoder for FP validation madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 09/20] objtool: arm64: Implement command to invoke the decoder madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 14:09 ` Mark Brown 2022-05-24 14:09 ` Mark Brown 2022-05-29 14:49 ` Madhavan T. Venkataraman 2022-05-29 14:49 ` Madhavan T. Venkataraman 2022-05-30 7:51 ` Peter Zijlstra 2022-05-30 7:51 ` Peter Zijlstra 2022-06-01 22:45 ` Madhavan T. Venkataraman 2022-06-01 22:45 ` Madhavan T. Venkataraman 2022-06-07 18:13 ` Madhavan T. Venkataraman 2022-06-07 18:13 ` Madhavan T. Venkataraman 2022-05-24 0:16 ` [RFC PATCH v2 10/20] objtool: arm64: Compute destinations for call and jump instructions madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` madvenka [this message] 2022-05-24 0:16 ` [RFC PATCH v2 11/20] objtool: arm64: Walk instructions and compute CFI for each instruction madvenka 2022-05-24 13:45 ` Chen Zhongjin 2022-05-24 13:45 ` Chen Zhongjin 2022-05-29 15:18 ` Madhavan T. Venkataraman 2022-05-29 15:18 ` Madhavan T. Venkataraman 2022-05-30 1:44 ` Chen Zhongjin 2022-05-30 1:44 ` Chen Zhongjin 2022-05-24 0:16 ` [RFC PATCH v2 12/20] objtool: arm64: Generate ORC data from CFI for object files madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 13/20] objtool: arm64: Dump ORC data present in " madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 14/20] objtool: arm64: Add unwind hint support madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 15/20] arm64: Add unwind hints to specific points in code madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 16/20] arm64: Add kernel and module support for ORC madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 17/20] arm64: Build the kernel with ORC information madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 18/20] arm64: unwinder: Add a reliability check in the unwinder based on ORC madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 0:16 ` [RFC PATCH v2 19/20] arm64: Miscellaneous changes required for enabling livepatch madvenka 2022-05-24 0:16 ` madvenka 2022-07-01 14:16 ` Miroslav Benes 2022-07-01 14:16 ` Miroslav Benes 2022-07-01 19:53 ` Madhavan T. Venkataraman 2022-07-01 19:53 ` Madhavan T. Venkataraman 2022-05-24 0:16 ` [RFC PATCH v2 20/20] arm64: Enable livepatch for ARM64 madvenka 2022-05-24 0:16 ` madvenka 2022-05-24 14:24 ` [RFC PATCH v2 00/20] arm64: livepatch: Use ORC for dynamic frame pointer validation Chen Zhongjin 2022-05-24 14:24 ` Chen Zhongjin 2022-05-29 15:30 ` Madhavan T. Venkataraman 2022-05-29 15:30 ` Madhavan T. Venkataraman 2022-06-15 12:18 ` Ivan T. Ivanov 2022-06-15 12:18 ` Ivan T. Ivanov 2022-06-15 13:37 ` Mark Rutland 2022-06-15 13:37 ` Mark Rutland 2022-06-15 14:18 ` Ivan T. Ivanov 2022-06-15 14:18 ` Ivan T. Ivanov 2022-06-15 20:50 ` Madhavan T. Venkataraman 2022-06-15 20:50 ` Madhavan T. Venkataraman 2022-06-15 20:47 ` Madhavan T. Venkataraman 2022-06-15 20:47 ` Madhavan T. Venkataraman
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