[PATCH] x86/purgatory: provide config to disable purgatory

From: Usama Arif
Date: Tue Nov 23 2021 - 10:05:45 EST

This can help in reducing boot time if purgatory is not needed
as the sha256 digest of kexec segments is no longer calculated
or verified if the config is disabled.

Signed-off-by: Usama Arif <usama.arif@xxxxxxxxxxxxx>
Reviewed-by: Fam Zheng <fam.zheng@xxxxxxxxxxxxx>
---
arch/powerpc/Kbuild | 2 +-
arch/powerpc/Kconfig | 2 +-
arch/s390/Kbuild | 2 +-
arch/s390/Kconfig | 2 +-
arch/s390/purgatory/Makefile | 2 +-
arch/x86/Kbuild | 2 +-
arch/x86/Kconfig | 6 ++--
arch/x86/kernel/kexec-bzimage64.c | 59 +++++++++++++++++++++------------------
arch/x86/purgatory/Makefile | 2 +-
kernel/kexec_file.c | 6 ++--
10 files changed, 46 insertions(+), 39 deletions(-)

diff --git a/arch/powerpc/Kbuild b/arch/powerpc/Kbuild
index 22cd0d55a892..072e62d7898e 100644
--- a/arch/powerpc/Kbuild
+++ b/arch/powerpc/Kbuild
@@ -15,7 +15,7 @@ obj-$(CONFIG_KVM) += kvm/

obj-$(CONFIG_PERF_EVENTS) += perf/
obj-$(CONFIG_KEXEC_CORE) += kexec/
-obj-$(CONFIG_KEXEC_FILE) += purgatory/
+obj-$(CONFIG_KEXEC_PURGATORY) += purgatory/

# for cleaning
subdir- += boot
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index dea74d7717c0..58bdfd1abb44 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -557,7 +557,7 @@ config KEXEC_FILE
for kernel and initramfs as opposed to a list of segments as is the
case for the older kexec call.

-config ARCH_HAS_KEXEC_PURGATORY
+config KEXEC_PURGATORY
def_bool KEXEC_FILE

config RELOCATABLE
diff --git a/arch/s390/Kbuild b/arch/s390/Kbuild
index 76e362277179..2ed4ee5cdf59 100644
--- a/arch/s390/Kbuild
+++ b/arch/s390/Kbuild
@@ -7,7 +7,7 @@ obj-$(CONFIG_S390_HYPFS_FS) += hypfs/
obj-$(CONFIG_APPLDATA_BASE) += appldata/
obj-y += net/
obj-$(CONFIG_PCI) += pci/
-obj-$(CONFIG_ARCH_HAS_KEXEC_PURGATORY) += purgatory/
+obj-$(CONFIG_KEXEC_PURGATORY) += purgatory/

# for cleaning
subdir- += boot tools
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 2a5bb4f29cfe..d15bdaa0e198 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -538,7 +538,7 @@ config KEXEC_FILE
kexec system call this system call takes file descriptors for the
kernel and initramfs as arguments.

-config ARCH_HAS_KEXEC_PURGATORY
+config KEXEC_PURGATORY
def_bool y
depends on KEXEC_FILE

diff --git a/arch/s390/purgatory/Makefile b/arch/s390/purgatory/Makefile
index 360ada80d20c..03cac6d7310a 100644
--- a/arch/s390/purgatory/Makefile
+++ b/arch/s390/purgatory/Makefile
@@ -51,4 +51,4 @@ $(obj)/purgatory.ro: $(obj)/purgatory $(obj)/purgatory.chk FORCE
$(obj)/kexec-purgatory.o: $(obj)/kexec-purgatory.S $(obj)/purgatory.ro FORCE
$(call if_changed_rule,as_o_S)

-obj-$(CONFIG_ARCH_HAS_KEXEC_PURGATORY) += kexec-purgatory.o
+obj-$(CONFIG_KEXEC_PURGATORY) += kexec-purgatory.o
diff --git a/arch/x86/Kbuild b/arch/x86/Kbuild
index f384cb1a4f7a..9089438ed6d8 100644
--- a/arch/x86/Kbuild
+++ b/arch/x86/Kbuild
@@ -24,7 +24,7 @@ obj-$(CONFIG_IA32_EMULATION) += ia32/
obj-y += platform/
obj-y += net/

-obj-$(CONFIG_KEXEC_FILE) += purgatory/
+obj-$(CONFIG_KEXEC_PURGATORY) += purgatory/

# for cleaning
subdir- += boot tools
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7399327d1eff..7efe6dbfdc67 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2000,8 +2000,10 @@ config KEXEC_FILE
for kernel and initramfs as opposed to list of segments as
accepted by previous system call.

-config ARCH_HAS_KEXEC_PURGATORY
- def_bool KEXEC_FILE
+config KEXEC_PURGATORY
+ bool "A standalone relocatable object run between the 2 kernels during kexec"
+ depends on KEXEC_FILE
+ default y

config KEXEC_SIG
bool "Verify kernel signature during kexec_file_load() syscall"
diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 170d0fd68b1f..bf37a2c4ab8b 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -374,18 +374,19 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
return ERR_PTR(ret);
}

- /*
- * Load purgatory. For 64bit entry point, purgatory code can be
- * anywhere.
- */
- ret = kexec_load_purgatory(image, &pbuf);
- if (ret) {
- pr_err("Loading purgatory failed\n");
- return ERR_PTR(ret);
- }
-
- pr_debug("Loaded purgatory at 0x%lx\n", pbuf.mem);
+ if (IS_ENABLED(CONFIG_KEXEC_PURGATORY)) {
+ /*
+ * Load purgatory. For 64bit entry point, purgatory code can be
+ * anywhere.
+ */
+ ret = kexec_load_purgatory(image, &pbuf);
+ if (ret) {
+ pr_err("Loading purgatory failed\n");
+ return ERR_PTR(ret);
+ }

+ pr_debug("Loaded purgatory at 0x%lx\n", pbuf.mem);
+ }

/*
* Load Bootparams and cmdline and space for efi stuff.
@@ -466,28 +467,32 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
params->hdr.type_of_loader = 0x0D << 4;
params->hdr.loadflags = 0;

- /* Setup purgatory regs for entry */
- ret = kexec_purgatory_get_set_symbol(image, "entry64_regs", &regs64,
- sizeof(regs64), 1);
- if (ret)
- goto out_free_params;
+ if (IS_ENABLED(CONFIG_KEXEC_PURGATORY)) {
+ /* Setup purgatory regs for entry */
+ ret = kexec_purgatory_get_set_symbol(image, "entry64_regs", &regs64,
+ sizeof(regs64), 1);
+ if (ret)
+ goto out_free_params;
+ }

regs64.rbx = 0; /* Bootstrap Processor */
regs64.rsi = bootparam_load_addr;
regs64.rip = kernel_load_addr + 0x200;
- stack = kexec_purgatory_get_symbol_addr(image, "stack_end");
- if (IS_ERR(stack)) {
- pr_err("Could not find address of symbol stack_end\n");
- ret = -EINVAL;
- goto out_free_params;
- }

- regs64.rsp = (unsigned long)stack;
- ret = kexec_purgatory_get_set_symbol(image, "entry64_regs", &regs64,
- sizeof(regs64), 0);
- if (ret)
- goto out_free_params;
+ if (IS_ENABLED(CONFIG_KEXEC_PURGATORY)) {
+ stack = kexec_purgatory_get_symbol_addr(image, "stack_end");
+ if (IS_ERR(stack)) {
+ pr_err("Could not find address of symbol stack_end\n");
+ ret = -EINVAL;
+ goto out_free_params;
+ }

+ regs64.rsp = (unsigned long)stack;
+ ret = kexec_purgatory_get_set_symbol(image, "entry64_regs", &regs64,
+ sizeof(regs64), 0);
+ if (ret)
+ goto out_free_params;
+ }
ret = setup_boot_parameters(image, params, bootparam_load_addr,
efi_map_offset, efi_map_sz,
efi_setup_data_offset);
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 95ea17a9d20c..688b3f21be8f 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -81,4 +81,4 @@ quiet_cmd_bin2c = BIN2C $@
$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro $(obj)/purgatory.chk FORCE
$(call if_changed,bin2c)

-obj-$(CONFIG_KEXEC_FILE) += kexec-purgatory.o
+obj-$(CONFIG_KEXEC_PURGATORY) += kexec-purgatory.o
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 8347fc158d2b..e5f4c2d27249 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -724,7 +724,7 @@ static int kexec_calculate_store_digests(struct kimage *image)
struct kexec_sha_region *sha_regions;
struct purgatory_info *pi = &image->purgatory_info;

- if (!IS_ENABLED(CONFIG_ARCH_HAS_KEXEC_PURGATORY))
+ if (!IS_ENABLED(CONFIG_KEXEC_PURGATORY))
return 0;

zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
@@ -829,7 +829,7 @@ static int kexec_calculate_store_digests(struct kimage *image)
return ret;
}

-#ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
+#ifdef CONFIG_KEXEC_PURGATORY
/*
* kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
* @pi: Purgatory to be loaded.
@@ -1176,7 +1176,7 @@ int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,

return 0;
}
-#endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */
+#endif /* CONFIG_KEXEC_PURGATORY */

int crash_exclude_mem_range(struct crash_mem *mem,
unsigned long long mstart, unsigned long long mend)
--
2.11.0