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objtool: Add support for alternatives at the end of a section
commit 17bc33914b
Now that the previous patch gave objtool the ability to read retpoline
alternatives, it shows a new warning:
arch/x86/entry/entry_64.o: warning: objtool: .entry_trampoline: don't know how to handle alternatives at end of section
This is due to the JMP_NOSPEC in entry_SYSCALL_64_trampoline().
Previously, objtool ignored this situation because it wasn't needed, and
it would have required a bit of extra code. Now that this case exists,
add proper support for it.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2a30a3c2158af47d891a76e69bb1ef347e0443fd.1517284349.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
a358df0327
commit
3e04e09855
1 changed files with 30 additions and 21 deletions
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@ -594,7 +594,7 @@ static int handle_group_alt(struct objtool_file *file,
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struct instruction *orig_insn,
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struct instruction *orig_insn,
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struct instruction **new_insn)
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struct instruction **new_insn)
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{
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{
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struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump;
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struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL;
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unsigned long dest_off;
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unsigned long dest_off;
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last_orig_insn = NULL;
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last_orig_insn = NULL;
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@ -610,28 +610,30 @@ static int handle_group_alt(struct objtool_file *file,
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last_orig_insn = insn;
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last_orig_insn = insn;
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}
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}
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if (!next_insn_same_sec(file, last_orig_insn)) {
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if (next_insn_same_sec(file, last_orig_insn)) {
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WARN("%s: don't know how to handle alternatives at end of section",
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fake_jump = malloc(sizeof(*fake_jump));
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special_alt->orig_sec->name);
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if (!fake_jump) {
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return -1;
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WARN("malloc failed");
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}
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return -1;
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}
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memset(fake_jump, 0, sizeof(*fake_jump));
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INIT_LIST_HEAD(&fake_jump->alts);
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clear_insn_state(&fake_jump->state);
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fake_jump = malloc(sizeof(*fake_jump));
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fake_jump->sec = special_alt->new_sec;
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if (!fake_jump) {
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fake_jump->offset = -1;
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WARN("malloc failed");
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fake_jump->type = INSN_JUMP_UNCONDITIONAL;
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return -1;
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fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
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fake_jump->ignore = true;
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}
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}
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memset(fake_jump, 0, sizeof(*fake_jump));
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INIT_LIST_HEAD(&fake_jump->alts);
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clear_insn_state(&fake_jump->state);
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fake_jump->sec = special_alt->new_sec;
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fake_jump->offset = -1;
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fake_jump->type = INSN_JUMP_UNCONDITIONAL;
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fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
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fake_jump->ignore = true;
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if (!special_alt->new_len) {
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if (!special_alt->new_len) {
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if (!fake_jump) {
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WARN("%s: empty alternative at end of section",
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special_alt->orig_sec->name);
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return -1;
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}
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*new_insn = fake_jump;
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*new_insn = fake_jump;
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return 0;
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return 0;
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}
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}
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@ -654,8 +656,14 @@ static int handle_group_alt(struct objtool_file *file,
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continue;
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continue;
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dest_off = insn->offset + insn->len + insn->immediate;
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dest_off = insn->offset + insn->len + insn->immediate;
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if (dest_off == special_alt->new_off + special_alt->new_len)
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if (dest_off == special_alt->new_off + special_alt->new_len) {
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if (!fake_jump) {
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WARN("%s: alternative jump to end of section",
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special_alt->orig_sec->name);
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return -1;
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}
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insn->jump_dest = fake_jump;
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insn->jump_dest = fake_jump;
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}
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if (!insn->jump_dest) {
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if (!insn->jump_dest) {
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WARN_FUNC("can't find alternative jump destination",
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WARN_FUNC("can't find alternative jump destination",
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@ -670,7 +678,8 @@ static int handle_group_alt(struct objtool_file *file,
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return -1;
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return -1;
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}
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}
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list_add(&fake_jump->list, &last_new_insn->list);
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if (fake_jump)
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list_add(&fake_jump->list, &last_new_insn->list);
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return 0;
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return 0;
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}
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}
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