arc, arm32, and csky all have these sections too, but I've never seen arc or csky in real life, and arm32 isn't as regular as riscv's "odd vs even" decoding, so we should probably wait until someone actually needs to decode those before adding the decoder? --- toys/other/readelf.c | 88 +++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 83 insertions(+), 5 deletions(-)
From ec9a224ed98981fcee95c0c71e6ea12a33b9a012 Mon Sep 17 00:00:00 2001 From: Elliott Hughes <e...@google.com> Date: Fri, 3 Nov 2023 17:22:00 -0700 Subject: [PATCH] readelf: decode RISCV_ATTRIBUTES sections.
arc, arm32, and csky all have these sections too, but I've never seen arc or csky in real life, and arm32 isn't as regular as riscv's "odd vs even" decoding, so we should probably wait until someone actually needs to decode those before adding the decoder? --- toys/other/readelf.c | 88 +++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 83 insertions(+), 5 deletions(-) diff --git a/toys/other/readelf.c b/toys/other/readelf.c index 3f6b49be..b5450677 100644 --- a/toys/other/readelf.c +++ b/toys/other/readelf.c @@ -4,17 +4,18 @@ * * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/nm.html -USE_READELF(NEWTOY(readelf, "<1(dyn-syms)adehlnp:SsWx:", TOYFLAG_USR|TOYFLAG_BIN)) +USE_READELF(NEWTOY(readelf, "<1(dyn-syms)Aadehlnp:SsWx:", TOYFLAG_USR|TOYFLAG_BIN)) config READELF bool "readelf" default y help - usage: readelf [-adehlnSs] [-p SECTION] [-x SECTION] [file...] + usage: readelf [-AadehlnSs] [-p SECTION] [-x SECTION] [file...] Displays information about ELF files. - -a Equivalent to -dhlnSs + -A Show architecture-specific info + -a Equivalent to -AdhlnSs -d Show dynamic section -e Headers (equivalent to -hlS) -h Show ELF header @@ -235,7 +236,7 @@ DECODER(sh_type, MAP({{0,"NULL"},{1,"PROGBITS"},{2,"SYMTAB"},{3,"STRTAB"}, {0x6fffff00,"ANDROID_RELR"},{0x6ffffff6,"GNU_HASH"}, {0x6ffffffd,"VERDEF"},{0x6ffffffe,"VERNEED"}, {0x6fffffff,"VERSYM"},{0x70000001,"ARM_EXIDX"}, - {0x70000003,"ARM_ATTRIBUTES"}})) + {0x70000003,"ATTRIBUTES"}})) DECODER(stb_type, MAP({{0,"LOCAL"},{1,"GLOBAL"},{2,"WEAK"}})) @@ -245,6 +246,10 @@ DECODER(stt_type, MAP({{0,"NOTYPE"},{1,"OBJECT"},{2,"FUNC"},{3,"SECTION"}, DECODER(stv_type, MAP({{0,"DEFAULT"},{1,"INTERNAL"},{2,"HIDDEN"}, {3,"PROTECTED"}})) +DECODER(riscv_attr_tag, MAP({{4,"stack_align"},{5,"arch"}, + {6,"unaligned_access"},{8,"priv_spec"},{10,"priv_spec_minor"}, + {12,"priv_spec_revision"},{14,"atomic_abi"},{16,"x3_reg_usage"}})) + static void show_symbols(struct sh *table, struct sh *strtab) { char *symtab = TT.elf+table->offset, *ndx; @@ -300,6 +305,69 @@ static int notematch(int namesz, char **p, char *expected) return 1; } +static unsigned long long uleb(char **ptr, char *end) +{ + unsigned long long result = 0; + int shift = 0; + unsigned char b; + + do { + if (*ptr >= end) error_exit("EOF in uleb128"); + b = **ptr; + *ptr = *ptr + 1; + result |= (b & 0x7f) << shift; + shift += 7; + if (shift > 56) error_exit("uleb128 too long"); + } while ((b & 0x80)); + return result; +} + +static void show_attributes(unsigned long offset, unsigned long size) +{ + char *attr = TT.elf + offset, *end = TT.elf + offset + size; + unsigned long long tag; + unsigned len; + + // Attributes sections start with an 'A'... + if (offset == size || *attr++ != 'A') + return error_msg("%s: bad attributes @%lu", TT.f, offset); + + // ...followed by vendor-specific subsections. + // TODO: there's a loop implied there, but i've never seen >1 subsection. + + // A subsection starts with a uint32 length and ASCII vendor name. + len = elf_int(&attr); + if (!memchr(attr, 0, 32)) return error_msg("%s: bad vendor name", TT.f); + printf("\nAttribute Section: %s\n", attr); + attr += strlen(attr) + 1; + + // ...followed by one or more sub-subsections. + // TODO: there's a loop implied there, but i've never seen >1 sub-subsection. + // A sub-subsection starts with a uleb128 tag and uint32 length. + tag = uleb(&attr, end); + len = elf_int(&attr); + if (tag == 1) { + printf("File Attributes\n"); + + // ...followed by actual attribute tag/value pairs. + while (attr < end) { + tag = uleb(&attr, end); + + // TODO: arm tags don't seem to follow any pattern? + printf(" Tag_RISCV_%s: ", riscv_attr_tag(tag)); + // Even riscv tags have uleb128 values, odd ones strings. + if (!(tag & 1)) printf("%lld\n", uleb(&attr, end)); + else { + printf("%s\n", attr); + attr += strlen(attr) + 1; + } + } + } else { + // Do other tags exist? + error_msg("%s: unknown attributes tag=%llx (size=%u)\n", TT.f, tag, len); + } +} + static void show_notes(unsigned long offset, unsigned long size) { char *note = TT.elf + offset; @@ -601,6 +669,16 @@ static void scan_elf() } } + // TODO: ARC/ARM/CSKY have these too. + if (FLAG(A) && machine == 243) { // RISCV + for (i=0; i<TT.shnum; i++) { + if (!get_sh(i, &s)) continue; + if (s.type == 0x70000003 /*SHT_RISCV_ATTRIBUTES*/) { + show_attributes(s.offset, s.size); + } + } + } + if (find_section(TT.x, &s)) { char *p = TT.elf+s.offset; long offset = 0; @@ -640,7 +718,7 @@ static void scan_elf() void readelf_main(void) { char **arg; - int all = FLAG_d|FLAG_h|FLAG_l|FLAG_n|FLAG_S|FLAG_s|FLAG_dyn_syms; + int all = FLAG_A|FLAG_d|FLAG_h|FLAG_l|FLAG_n|FLAG_S|FLAG_s|FLAG_dyn_syms; if (FLAG(a)) toys.optflags |= all; if (FLAG(e)) toys.optflags |= FLAG_h|FLAG_l|FLAG_S; -- 2.42.0.869.gea05f2083d-goog
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