Jan H. Schönherr <jschoenh@xxxxxxxxx> writes: > Give the administrator the ability to trade kexec safety for kexec speed > by disabling the digest calculation/verification for regular kexecs. > > The behavior of kexec-on-crash is not touched. The performance of the digest caculation is acceptable on 386s. Or it was years ago when I tested it on a 386. What is the problem you are having. Is there something silly like a cache disable in your configuration? Eric > Signed-off-by: Jan H. Schönherr <jschoenh@xxxxxxxxx> > --- > arch/x86/Kconfig | 12 ++++++++++++ > arch/x86/purgatory/purgatory.c | 9 +++++++++ > kernel/kexec_file.c | 5 +++++ > 3 files changed, 26 insertions(+) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 20da391b5f32..7b257f655327 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1984,6 +1984,18 @@ config KEXEC_BZIMAGE_VERIFY_SIG > ---help--- > Enable bzImage signature verification support. > > +config KEXEC_SKIP_NONCRASH_DIGEST > + bool "Disable digest calculation for regular kexec" > + depends on KEXEC > + ---help--- > + Disable the calculation and verification of the SHA digest before > + and during a regular kexec. This speeds up kexec a bit at the cost > + of a bit of safety. > + > + Note, that the digest calculation is still done for a kexec-on-crash. > + > + If unsure, say N. > + > config CRASH_DUMP > bool "kernel crash dumps" > depends on X86_64 || (X86_32 && HIGHMEM) > diff --git a/arch/x86/purgatory/purgatory.c b/arch/x86/purgatory/purgatory.c > index 470edad96bb9..2b5189b851b3 100644 > --- a/arch/x86/purgatory/purgatory.c > +++ b/arch/x86/purgatory/purgatory.c > @@ -44,6 +44,15 @@ static int verify_sha256_digest(void) > u8 digest[SHA256_DIGEST_SIZE]; > struct sha256_state sctx; > > +#ifdef CONFIG_KEXEC_SKIP_NONCRASH_DIGEST > + /* > + * Skip digest verification for non-crash kernels, we trust the > + * mechanism enough to trade-off the digest for a quicker kexec > + */ > + if (!purgatory_backup_dest) > + return 0; > +#endif > + > sha256_init(&sctx); > end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions); > > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index e5bcd94c1efb..ac01b34a7f87 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -532,6 +532,11 @@ static int kexec_calculate_store_digests(struct kimage *image) > struct kexec_sha_region *sha_regions; > struct purgatory_info *pi = &image->purgatory_info; > > +#ifdef CONFIG_KEXEC_SKIP_NONCRASH_DIGEST > + if (image->type != KEXEC_TYPE_CRASH) > + return 0; > +#endif > + > zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT); > zero_buf_sz = PAGE_SIZE; _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
