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ANDROID: objtool: Ignore CFI jump tables

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Skip checking for the compiler-generated jump table symbols when Clang's
Control-Flow Integrity (CFI) is enabled.

Bug: 145210207
Change-Id: Icd1fad50214016348289ac5980b062708ab9ecd0
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
This commit is contained in:
Sami Tolvanen
2020-04-14 16:20:30 -07:00
committed by Alistair Delva
parent e135c46cdf
commit 66d2edaa08
1 changed files with 40 additions and 1 deletions
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41
tools/objtool/check.c
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@@ -825,6 +825,37 @@ static int add_ignore_alternatives(struct objtool_file *file)
return 0;
}
/*
* CONFIG_CFI_CLANG: Check if the section is a CFI jump table or a
* compiler-generated CFI handler.
*/
static bool is_cfi_section(struct section *sec)
{
return (sec->name &&
(!strncmp(sec->name, ".text..L.cfi.jumptable", 22) ||
!strcmp(sec->name, ".text.__cfi_check")));
}
/*
* CONFIG_CFI_CLANG: Ignore CFI jump tables.
*/
static void add_cfi_jumptables(struct objtool_file *file)
{
struct section *sec;
struct symbol *func;
struct instruction *insn;
for_each_sec(file, sec) {
if (!is_cfi_section(sec))
continue;
list_for_each_entry(func, &sec->symbol_list, list) {
sym_for_each_insn(file, func, insn)
insn->ignore = true;
}
}
}
/*
* Find the destination instructions for all jumps.
*/
@@ -887,6 +918,9 @@ static int add_jump_destinations(struct objtool_file *file)
if (!strcmp(insn->sec->name, ".altinstr_replacement"))
continue;
if (is_cfi_section(insn->sec))
continue;
WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
insn->sec, insn->offset, dest_sec->name,
dest_off);
@@ -994,6 +1028,9 @@ static int add_call_destinations(struct objtool_file *file)
insn->call_dest = find_call_destination(reloc->sym->sec,
dest_off);
if (!insn->call_dest) {
if (is_cfi_section(reloc->sym->sec))
continue;
WARN_FUNC("can't find call dest symbol at %s+0x%lx",
insn->sec, insn->offset,
reloc->sym->sec->name,
@@ -1728,6 +1765,7 @@ static int decode_sections(struct objtool_file *file)
add_ignores(file);
add_uaccess_safe(file);
add_cfi_jumptables(file);
ret = add_ignore_alternatives(file);
if (ret)
@@ -2599,7 +2637,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
if (dead_end_function(file, insn->call_dest))
return 0;
if (insn->type == INSN_CALL && insn->call_dest->static_call_tramp) {
if (insn->type == INSN_CALL && insn->call_dest &&
insn->call_dest->static_call_tramp) {
list_add_tail(&insn->static_call_node,
&file->static_call_list);
}