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x86/retbleed: Add fine grained Kconfig knobs

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commit f43b9876e857c739d407bc56df288b0ebe1a9164 upstream.

Do fine-grained Kconfig for all the various retbleed parts.

NOTE: if your compiler doesn't support return thunks this will
silently 'upgrade' your mitigation to IBPB, you might not like this.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
[cascardo: there is no CONFIG_OBJTOOL]
[cascardo: objtool calling and option parsing has changed]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Zijlstra
2022-06-27 22:21:17 +00:00
committed by Greg Kroah-Hartman
parent 12a1357005
commit cc3011cdbe
19 changed files with 170 additions and 69 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
tools/objtool/builtin-check.c
View File

@@ -20,7 +20,7 @@
#include <objtool/objtool.h>
bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
validate_dup, vmlinux, mcount, noinstr, backup, sls, unret;
validate_dup, vmlinux, mcount, noinstr, backup, sls, unret, rethunk;
static const char * const check_usage[] = {
"objtool check [<options>] file.o",
@@ -36,6 +36,7 @@ const struct option check_options[] = {
OPT_BOOLEAN('f', "no-fp", &no_fp, "Skip frame pointer validation"),
OPT_BOOLEAN('u', "no-unreachable", &no_unreachable, "Skip 'unreachable instruction' warnings"),
OPT_BOOLEAN('r', "retpoline", &retpoline, "Validate retpoline assumptions"),
OPT_BOOLEAN(0, "rethunk", &rethunk, "validate and annotate rethunk usage"),
OPT_BOOLEAN(0, "unret", &unret, "validate entry unret placement"),
OPT_BOOLEAN('m', "module", &module, "Indicates the object will be part of a kernel module"),
OPT_BOOLEAN('b', "backtrace", &backtrace, "unwind on error"),

9
tools/objtool/check.c
View File

@@ -3440,8 +3440,11 @@ static int validate_retpoline(struct objtool_file *file)
continue;
if (insn->type == INSN_RETURN) {
WARN_FUNC("'naked' return found in RETPOLINE build",
insn->sec, insn->offset);
if (rethunk) {
WARN_FUNC("'naked' return found in RETHUNK build",
insn->sec, insn->offset);
} else
continue;
} else {
WARN_FUNC("indirect %s found in RETPOLINE build",
insn->sec, insn->offset,
@@ -3711,7 +3714,9 @@ int check(struct objtool_file *file)
if (ret < 0)
goto out;
warnings += ret;
}
if (rethunk) {
ret = create_return_sites_sections(file);
if (ret < 0)
goto out;

2
tools/objtool/include/objtool/builtin.h
View File

@@ -9,7 +9,7 @@
extern const struct option check_options[];
extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
validate_dup, vmlinux, mcount, noinstr, backup, sls, unret;
validate_dup, vmlinux, mcount, noinstr, backup, sls, unret, rethunk;
extern int cmd_parse_options(int argc, const char **argv, const char * const usage[]);