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From: Sami Tolvanen <samitolvanen@google.com>
To: Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>
Cc: Kees Cook <keescook@chromium.org>,
	Kristen Carlson Accardi <kristen@linux.intel.com>,
	linux-kernel@vger.kernel.org,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v2 1/2] objtool: use gelf_getsymshndx to handle >64k sections
Date: Tue, 21 Apr 2020 15:08:42 -0700	[thread overview]
Message-ID: <20200421220843.188260-2-samitolvanen@google.com> (raw)
In-Reply-To: <20200421220843.188260-1-samitolvanen@google.com>

Currently, objtool fails to load the correct section for symbols when
the index is greater than SHN_LORESERVE. Use gelf_getsymshndx instead
of gelf_getsym to handle >64k sections.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 tools/objtool/elf.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 09ddc8f1def3..887445e87380 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -327,12 +327,14 @@ static int read_sections(struct elf *elf)
 
 static int read_symbols(struct elf *elf)
 {
-	struct section *symtab, *sec;
+	struct section *symtab, *symtab_shndx, *sec;
 	struct symbol *sym, *pfunc;
 	struct list_head *entry;
 	struct rb_node *pnode;
 	int symbols_nr, i;
 	char *coldstr;
+	Elf_Data *shndx_data = NULL;
+	Elf32_Word shndx;
 
 	symtab = find_section_by_name(elf, ".symtab");
 	if (!symtab) {
@@ -340,6 +342,10 @@ static int read_symbols(struct elf *elf)
 		return -1;
 	}
 
+	symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
+	if (symtab_shndx)
+		shndx_data = symtab_shndx->data;
+
 	symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
 
 	for (i = 0; i < symbols_nr; i++) {
@@ -353,8 +359,9 @@ static int read_symbols(struct elf *elf)
 
 		sym->idx = i;
 
-		if (!gelf_getsym(symtab->data, i, &sym->sym)) {
-			WARN_ELF("gelf_getsym");
+		if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym,
+				      &shndx)) {
+			WARN_ELF("gelf_getsymshndx");
 			goto err;
 		}
 
@@ -368,10 +375,13 @@ static int read_symbols(struct elf *elf)
 		sym->type = GELF_ST_TYPE(sym->sym.st_info);
 		sym->bind = GELF_ST_BIND(sym->sym.st_info);
 
-		if (sym->sym.st_shndx > SHN_UNDEF &&
-		    sym->sym.st_shndx < SHN_LORESERVE) {
-			sym->sec = find_section_by_index(elf,
-							 sym->sym.st_shndx);
+		if ((sym->sym.st_shndx > SHN_UNDEF &&
+		     sym->sym.st_shndx < SHN_LORESERVE) ||
+		    (shndx_data && sym->sym.st_shndx == SHN_XINDEX)) {
+			if (sym->sym.st_shndx != SHN_XINDEX)
+				shndx = sym->sym.st_shndx;
+
+			sym->sec = find_section_by_index(elf, shndx);
 			if (!sym->sec) {
 				WARN("couldn't find section for symbol %s",
 				     sym->name);
-- 
2.26.1.301.g55bc3eb7cb9-goog


  reply	other threads:[~2020-04-21 22:08 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-21 18:07 [PATCH 0/3] objtool: add support for >64k sections Sami Tolvanen
2020-04-21 18:07 ` [PATCH 1/3] objtool: use gelf_getsymshndx to handle " Sami Tolvanen
2020-04-21 20:11   ` Kees Cook
2020-04-21 18:07 ` [PATCH 2/3] objtool: optimize insn_hash for split sections Sami Tolvanen
2020-04-21 19:47   ` Peter Zijlstra
2020-04-21 20:13     ` Kees Cook
2020-04-21 20:20     ` Sami Tolvanen
2020-04-21 18:07 ` [PATCH 3/3] objtool: optimize add_dead_ends " Sami Tolvanen
2020-04-21 20:13   ` Josh Poimboeuf
2020-04-21 20:17     ` Kees Cook
2020-04-21 22:02     ` Sami Tolvanen
2020-04-21 20:14   ` Kees Cook
2020-04-21 20:11 ` [PATCH 0/3] objtool: add support for >64k sections Kees Cook
2020-04-21 22:08 ` [PATCH v2 0/2] " Sami Tolvanen
2020-04-21 22:08   ` Sami Tolvanen [this message]
2020-05-15 17:22     ` [tip: objtool/core] objtool: use gelf_getsymshndx to handle " tip-bot2 for Sami Tolvanen
2020-04-21 22:08   ` [PATCH v2 2/2] objtool: optimize add_dead_ends for split sections Sami Tolvanen
2020-04-21 23:43     ` Kees Cook
2020-05-15 17:22     ` [tip: objtool/core] " tip-bot2 for Sami Tolvanen
2020-04-21 23:52   ` [PATCH v2 0/2] objtool: add support for >64k sections Josh Poimboeuf

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