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objtool: Fix infinite loop in find_jump_table()

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Kristen found a hang in objtool when building with -ffunction-sections.

It was caused by evergreen_pcie_gen2_enable.cold() being laid out
immediately before evergreen_pcie_gen2_enable().  Since their "pfunc" is
always the same, find_jump_table() got into an infinite loop because it
didn't recognize the boundary between the two functions.

Fix that with a new prev_insn_same_sym() helper, which doesn't cross
subfunction boundaries.

Reported-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/378b51c9d9c894dc3294bc460b4b0869e950b7c5.1588110291.git.jpoimboe@redhat.com
This commit is contained in:
Josh Poimboeuf 2020-04-28 16:45:16 -05:00 committed by Peter Zijlstra
parent 0e698dfa28
commit 1119d265bc
1 changed files with 13 additions and 2 deletions
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15
tools/objtool/check.c
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@ -72,6 +72,17 @@ static struct instruction *next_insn_same_func(struct objtool_file *file,
return find_insn(file, func->cfunc->sec, func->cfunc->offset);
}
static struct instruction *prev_insn_same_sym(struct objtool_file *file,
struct instruction *insn)
{
struct instruction *prev = list_prev_entry(insn, list);
if (&prev->list != &file->insn_list && prev->func == insn->func)
return prev;
return NULL;
}
#define func_for_each_insn(file, func, insn) \
for (insn = find_insn(file, func->sec, func->offset); \
insn; \
@ -1050,8 +1061,8 @@ static struct rela *find_jump_table(struct objtool_file *file,
* it.
*/
for (;
&insn->list != &file->insn_list && insn->func && insn->func->pfunc == func;
insn = insn->first_jump_src ?: list_prev_entry(insn, list)) {
insn && insn->func && insn->func->pfunc == func;
insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
break;