From efb11fdb3e1a9f694fa12b70b21e69e55ec59c36 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Mon, 14 Nov 2022 23:27:46 +0530 Subject: objtool: Fix SEGFAULT find_insn() will return NULL in case of failure. Check insn in order to avoid a kernel Oops for NULL pointer dereference. Tested-by: Naveen N. Rao Reviewed-by: Naveen N. Rao Acked-by: Josh Poimboeuf Acked-by: Peter Zijlstra (Intel) Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114175754.1131267-9-sv@linux.ibm.com --- tools/objtool/check.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 43ec14c29a60..8427af808221 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -207,7 +207,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, return false; insn = find_insn(file, func->sec, func->offset); - if (!insn->func) + if (!insn || !insn->func) return false; func_for_each_insn(file, func, insn) { -- cgit From 0646c28b417b7fe307c9da72ca1c508e43b57dc0 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Mon, 14 Nov 2022 23:27:47 +0530 Subject: objtool: Use target file endianness instead of a compiled constant Some architectures like powerpc support both endianness, it's therefore not possible to fix the endianness via arch/endianness.h because there is no easy way to get the target endianness at build time. Use the endianness recorded in the file objtool is working on. Tested-by: Naveen N. Rao Reviewed-by: Naveen N. Rao Acked-by: Josh Poimboeuf Acked-by: Peter Zijlstra (Intel) Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114175754.1131267-10-sv@linux.ibm.com --- tools/objtool/check.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 8427af808221..ad5dab175701 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2100,7 +2100,7 @@ static int read_unwind_hints(struct objtool_file *file) return -1; } - cfi.cfa.offset = bswap_if_needed(hint->sp_offset); + cfi.cfa.offset = bswap_if_needed(file->elf, hint->sp_offset); cfi.type = hint->type; cfi.end = hint->end; -- cgit From 86ea7f361537f825a699e86fdc9e49be19f128d1 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Mon, 14 Nov 2022 23:27:48 +0530 Subject: objtool: Use target file class size instead of a compiled constant In order to allow using objtool on cross-built kernels, determine size of long from elf data instead of using sizeof(long) at build time. For the time being this covers only mcount. [Sathvika Vasireddy: Rename variable "size" to "addrsize" and function "elf_class_size()" to "elf_class_addrsize()", and modify create_mcount_loc_sections() function to follow reverse christmas tree format to order local variable declarations.] Tested-by: Naveen N. Rao Reviewed-by: Naveen N. Rao Acked-by: Josh Poimboeuf Acked-by: Peter Zijlstra (Intel) Signed-off-by: Christophe Leroy Signed-off-by: Sathvika Vasireddy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114175754.1131267-11-sv@linux.ibm.com --- tools/objtool/check.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index ad5dab175701..b64518c7c7b4 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -852,9 +852,9 @@ static int create_ibt_endbr_seal_sections(struct objtool_file *file) static int create_mcount_loc_sections(struct objtool_file *file) { - struct section *sec; - unsigned long *loc; + int addrsize = elf_class_addrsize(file->elf); struct instruction *insn; + struct section *sec; int idx; sec = find_section_by_name(file->elf, "__mcount_loc"); @@ -871,23 +871,25 @@ static int create_mcount_loc_sections(struct objtool_file *file) list_for_each_entry(insn, &file->mcount_loc_list, call_node) idx++; - sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx); + sec = elf_create_section(file->elf, "__mcount_loc", 0, addrsize, idx); if (!sec) return -1; + sec->sh.sh_addralign = addrsize; + idx = 0; list_for_each_entry(insn, &file->mcount_loc_list, call_node) { + void *loc; - loc = (unsigned long *)sec->data->d_buf + idx; - memset(loc, 0, sizeof(unsigned long)); + loc = sec->data->d_buf + idx; + memset(loc, 0, addrsize); - if (elf_add_reloc_to_insn(file->elf, sec, - idx * sizeof(unsigned long), + if (elf_add_reloc_to_insn(file->elf, sec, idx, R_X86_64_64, insn->sec, insn->offset)) return -1; - idx++; + idx += addrsize; } return 0; -- cgit From 280981d6994e0700abd36647b141e73059851e66 Mon Sep 17 00:00:00 2001 From: Sathvika Vasireddy Date: Mon, 14 Nov 2022 23:27:49 +0530 Subject: objtool: Add --mnop as an option to --mcount Some architectures (powerpc) may not support ftrace locations being nop'ed out at build time. Introduce CONFIG_HAVE_OBJTOOL_NOP_MCOUNT for objtool, as a means for architectures to enable nop'ing of ftrace locations. Add --mnop as an option to objtool --mcount, to indicate support for the same. Also, make sure that --mnop can be passed as an option to objtool only when --mcount is passed. Tested-by: Naveen N. Rao Reviewed-by: Naveen N. Rao Acked-by: Josh Poimboeuf Reviewed-by: Christophe Leroy Signed-off-by: Sathvika Vasireddy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114175754.1131267-12-sv@linux.ibm.com --- tools/objtool/check.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index b64518c7c7b4..71cf4b4ba1da 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1256,17 +1256,18 @@ static void annotate_call_site(struct objtool_file *file, if (opts.mcount && sym->fentry) { if (sibling) WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset); + if (opts.mnop) { + if (reloc) { + reloc->type = R_NONE; + elf_write_reloc(file->elf, reloc); + } - if (reloc) { - reloc->type = R_NONE; - elf_write_reloc(file->elf, reloc); - } - - elf_write_insn(file->elf, insn->sec, - insn->offset, insn->len, - arch_nop_insn(insn->len)); + elf_write_insn(file->elf, insn->sec, + insn->offset, insn->len, + arch_nop_insn(insn->len)); - insn->type = INSN_NOP; + insn->type = INSN_NOP; + } list_add_tail(&insn->call_node, &file->mcount_loc_list); return; -- cgit From de6fbcedf5abce4c321eeb15d7d286b79804b8b6 Mon Sep 17 00:00:00 2001 From: Sathvika Vasireddy Date: Mon, 14 Nov 2022 23:27:50 +0530 Subject: objtool: Read special sections with alts only when specific options are selected Call add_special_section_alts() only when stackval or orc or uaccess or noinstr options are passed to objtool. Tested-by: Naveen N. Rao Reviewed-by: Naveen N. Rao Reviewed-by: Christophe Leroy Acked-by: Josh Poimboeuf Signed-off-by: Sathvika Vasireddy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114175754.1131267-13-sv@linux.ibm.com --- tools/objtool/check.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 71cf4b4ba1da..752a6ffd5c4c 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2392,9 +2392,11 @@ static int decode_sections(struct objtool_file *file) * Must be before add_jump_destinations(), which depends on 'func' * being set for alternatives, to enable proper sibling call detection. */ - ret = add_special_section_alts(file); - if (ret) - return ret; + if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr) { + ret = add_special_section_alts(file); + if (ret) + return ret; + } ret = add_jump_destinations(file); if (ret) -- cgit From c1449735211dd8c4c2d54fa0ece6890ecbd74e24 Mon Sep 17 00:00:00 2001 From: Sathvika Vasireddy Date: Mon, 14 Nov 2022 23:27:51 +0530 Subject: objtool: Use macros to define arch specific reloc types Make relocation types architecture specific. Tested-by: Naveen N. Rao Reviewed-by: Naveen N. Rao Reviewed-by: Christophe Leroy Acked-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Signed-off-by: Sathvika Vasireddy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114175754.1131267-14-sv@linux.ibm.com --- tools/objtool/check.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 752a6ffd5c4c..2d7153b5d5d1 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -885,7 +885,7 @@ static int create_mcount_loc_sections(struct objtool_file *file) memset(loc, 0, addrsize); if (elf_add_reloc_to_insn(file->elf, sec, idx, - R_X86_64_64, + addrsize == sizeof(u64) ? R_ABS64 : R_ABS32, insn->sec, insn->offset)) return -1; -- cgit From 4ca993d498987332ceeedee5380101b84accaf35 Mon Sep 17 00:00:00 2001 From: Sathvika Vasireddy Date: Mon, 14 Nov 2022 23:27:52 +0530 Subject: objtool: Add arch specific function arch_ftrace_match() Add architecture specific function to look for relocation records pointing to architecture specific symbols. Suggested-by: Christophe Leroy Tested-by: Naveen N. Rao Reviewed-by: Naveen N. Rao Reviewed-by: Christophe Leroy Acked-by: Josh Poimboeuf Signed-off-by: Sathvika Vasireddy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114175754.1131267-15-sv@linux.ibm.com --- tools/objtool/check.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 2d7153b5d5d1..7580c66ca5c8 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2316,7 +2316,7 @@ static int classify_symbols(struct objtool_file *file) if (arch_is_rethunk(func)) func->return_thunk = true; - if (!strcmp(func->name, "__fentry__")) + if (arch_ftrace_match(func->name)) func->fentry = true; if (is_profiling_func(func->name)) -- cgit