Add a new option --no-checks to kexec that allows for a fast
reboot by avoiding the purgatory integrity checks. This option is
intended for use by kexec based bootloaders that load a new
image and then immediately transfer control to it.
Signed-off-by: Geoff Levand <geoff@xxxxxxxxxxxxx>
---
Hi Simon,
On 10/21/2015 04:12 PM, Geoff Levand wrote:
> Hi Simon,
>
> It was reported that on some systems where purgatory is running
> without caches enabled the sha256 calculations would take several
> minutes. For bootloaders that just load a new image and
> immediately jump into it the loss of the integrity check is worth
> the increase in boot speed. Please consider.
There seems to be continued interest in faster kexec re-boot times
on arm64 systems so I rebased my old patch and renamed the
option from '--lite' to '--no-checks'. Please consider.
-Geoff
kexec/kexec.8 | 3 +++
kexec/kexec.c | 19 +++++++++++++++++--
kexec/kexec.h | 6 +++++-
purgatory/purgatory.c | 3 ++-
4 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/kexec/kexec.8 b/kexec/kexec.8
index fb8a4c9..2fafaaa 100644
--- a/kexec/kexec.8
+++ b/kexec/kexec.8
@@ -132,6 +132,9 @@ in one call.
Open a help file for
.BR kexec .
.TP
+.B \-i\ (\-\-no-checks)
+Fast reboot, no memory integrity checks.
+.TP
.BI \-l\ (\-\-load) \ kernel
Load the specified
.I kernel
diff --git a/kexec/kexec.c b/kexec/kexec.c
index 313d9fe..a512047 100644
--- a/kexec/kexec.c
+++ b/kexec/kexec.c
@@ -647,6 +647,15 @@ static void update_purgatory(struct kexec_info *info)
return;
}
arch_update_purgatory(info);
+
+ if (info->skip_checks) {
+ unsigned int tmp = 1;
+
+ elf_rel_set_symbol(&info->rhdr, "skip_checks", &tmp,
+ sizeof(tmp));
+ return;
+ }
+
memset(region, 0, sizeof(region));
sha256_starts(&ctx);
/* Compute a hash of the loaded kernel */
@@ -686,7 +695,7 @@ static void update_purgatory(struct kexec_info *info)
* Load the new kernel
*/
static int my_load(const char *type, int fileind, int argc, char **argv,
- unsigned long kexec_flags, void *entry)
+ unsigned long kexec_flags, int skip_checks, void *entry)
{
char *kernel;
char *kernel_buf;
@@ -699,6 +708,7 @@ static int my_load(const char *type, int fileind, int argc, char **argv,
memset(&info, 0, sizeof(info));
info.kexec_flags = kexec_flags;
+ info.skip_checks = skip_checks;
result = 0;
if (argc - fileind <= 0) {
@@ -980,6 +990,7 @@ void usage(void)
" -v, --version Print the version of kexec.\n"
" -f, --force Force an immediate kexec,\n"
" don't call shutdown.\n"
+ " -i, --no-checks Fast reboot, no memory integrity checks.\n"
" -x, --no-ifdown Don't bring down network interfaces.\n"
" -y, --no-sync Don't sync filesystems before kexec.\n"
" -l, --load Load the new kernel into the\n"
@@ -1250,6 +1261,7 @@ int main(int argc, char *argv[])
int do_reuse_initrd = 0;
int do_kexec_file_syscall = 0;
int do_kexec_fallback = 0;
+ int skip_checks = 0;
int do_status = 0;
void *entry = 0;
char *type = 0;
@@ -1385,6 +1397,9 @@ int main(int argc, char *argv[])
do_kexec_file_syscall = 1;
do_kexec_fallback = 1;
break;
+ case OPT_NOCHECKS:
+ skip_checks = 1;
+ break;
case OPT_STATUS:
do_status = 1;
break;
@@ -1519,7 +1534,7 @@ int main(int argc, char *argv[])
}
if (!do_kexec_file_syscall)
result = my_load(type, fileind, argc, argv,
- kexec_flags, entry);
+ kexec_flags, skip_checks, entry);
}
/* Don't shutdown unless there is something to reboot to! */
if ((result == 0) && (do_shutdown || do_exec) && !kexec_loaded(KEXEC_LOADED_PATH)) {
diff --git a/kexec/kexec.h b/kexec/kexec.h
index d445fbe..a97b9ce 100644
--- a/kexec/kexec.h
+++ b/kexec/kexec.h
@@ -166,6 +166,8 @@ struct kexec_info {
int initrd_fd;
char *command_line;
int command_line_len;
+
+ int skip_checks;
};
struct arch_map_entry {
@@ -211,6 +213,7 @@ extern int file_types;
#define OPT_VERSION 'v'
#define OPT_DEBUG 'd'
#define OPT_FORCE 'f'
+#define OPT_NOCHECKS 'i'
#define OPT_NOIFDOWN 'x'
#define OPT_NOSYNC 'y'
#define OPT_EXEC 'e'
@@ -234,6 +237,7 @@ extern int file_types;
{ "help", 0, 0, OPT_HELP }, \
{ "version", 0, 0, OPT_VERSION }, \
{ "force", 0, 0, OPT_FORCE }, \
+ { "no-checks", 0, 0, OPT_NOCHECKS }, \
{ "no-ifdown", 0, 0, OPT_NOIFDOWN }, \
{ "no-sync", 0, 0, OPT_NOSYNC }, \
{ "load", 0, 0, OPT_LOAD }, \
@@ -254,7 +258,7 @@ extern int file_types;
{ "status", 0, 0, OPT_STATUS }, \
{ "print-ckr-size", 0, 0, OPT_PRINT_CKR_SIZE }, \
-#define KEXEC_OPT_STR "h?vdfxyluet:pscaS"
+#define KEXEC_OPT_STR "h?vdfixyluet:pscaS"
extern void dbgprint_mem_range(const char *prefix, struct memory_range *mr, int nr_mr);
extern void die(const char *fmt, ...)
diff --git a/purgatory/purgatory.c b/purgatory/purgatory.c
index 3bbcc09..73930aa 100644
--- a/purgatory/purgatory.c
+++ b/purgatory/purgatory.c
@@ -8,6 +8,7 @@
struct sha256_region sha256_regions[SHA256_REGIONS] = {};
sha256_digest_t sha256_digest = { };
+int skip_checks = 0;
int verify_sha256_digest(void)
{
@@ -43,7 +44,7 @@ void purgatory(void)
{
printf("I'm in purgatory\n");
setup_arch();
- if (verify_sha256_digest()) {
+ if (!skip_checks && verify_sha256_digest()) {
for(;;) {
/* loop forever */
}
--
2.14.1
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