In purgatory(), the main things are as below:
[1] verify sha256 hashes for various segments.
Lets keep these codes, and do not touch the logic.
[2] copy the first 640k content to a backup region.
Lets safely remove it and clean all code related to backup region.
This patch series will remove the backup region, because the current
handling of copying the first 640k runs into problems when SME is
active(https://bugzilla.kernel.org/show_bug.cgi?id=204793).
The low 1MiB region will always be reserved when the crashkernel kernel
command line option is specified. And this way makes it unnecessary to
do anything with the low 1MiB region, because the memory allocated later
won't fall into the low 1MiB area.
This series includes three patches:
[1] x86/kdump: always reserve the low 1MiB when the crashkernel option
is specified
The low 1MiB region will always be reserved when the crashkernel
kernel command line option is specified, which ensures that the
memory allocated later won't fall into the low 1MiB area.
[2] x86/kdump: remove the unused crash_copy_backup_region()
The crash_copy_backup_region() has never been used, so clean
up the redundant code.
[3] x86/kdump: clean up all the code related to the backup region
Remove the backup region and clean up.
Changes since v1:
[1] Add extra checking condition: when the crashkernel option is
specified, reserve the low 640k area.
Changes since v2:
[1] Reserve the low 1MiB region when the crashkernel option is only
specified.(Suggested by Eric)
[2] Remove the unused crash_copy_backup_region()
[3] Remove the backup region and clean up
[4] Split them into three patches
Changes since v3:
[1] Improve the first patch's log
[2] Improve the third patch based on Eric's suggestions
Lianbo Jiang (3):
x86/kdump: always reserve the low 1MiB when the crashkernel option is
specified
x86/kdump: remove the unused crash_copy_backup_region()
x86/kdump: clean up all the code related to the backup region
arch/x86/include/asm/crash.h | 1 -
arch/x86/include/asm/kexec.h | 10 ----
arch/x86/include/asm/purgatory.h | 10 ----
arch/x86/kernel/crash.c | 87 ++++--------------------------
arch/x86/kernel/machine_kexec_64.c | 47 ----------------
arch/x86/purgatory/purgatory.c | 19 -------
arch/x86/realmode/init.c | 11 ++++
7 files changed, 22 insertions(+), 163 deletions(-)
--
2.17.1
The crash_copy_backup_region() has never been used, so clean
up the redundant code.
Signed-off-by: Lianbo Jiang <[email protected]>
---
arch/x86/include/asm/crash.h | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/x86/include/asm/crash.h b/arch/x86/include/asm/crash.h
index 0acf5ee45a21..089b2850f9d1 100644
--- a/arch/x86/include/asm/crash.h
+++ b/arch/x86/include/asm/crash.h
@@ -3,7 +3,6 @@
#define _ASM_X86_CRASH_H
int crash_load_segments(struct kimage *image);
-int crash_copy_backup_region(struct kimage *image);
int crash_setup_memmap_entries(struct kimage *image,
struct boot_params *params);
void crash_smp_send_stop(void);
--
2.17.1
When the crashkernel kernel command line option is specified, the
low 1MiB memory will always be reserved, which makes that the memory
allocated later won't fall into the low 1MiB area, thereby, it's not
necessary to create a backup region and also no need to copy the first
640k content to a backup region.
Currently, the code related to the backup region can be safely removed,
so lets clean up.
Signed-off-by: Lianbo Jiang <[email protected]>
---
arch/x86/include/asm/kexec.h | 10 ----
arch/x86/include/asm/purgatory.h | 10 ----
arch/x86/kernel/crash.c | 87 ++++--------------------------
arch/x86/kernel/machine_kexec_64.c | 47 ----------------
arch/x86/purgatory/purgatory.c | 19 -------
5 files changed, 11 insertions(+), 162 deletions(-)
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index 5e7d6b46de97..6802c59e8252 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -66,10 +66,6 @@ struct kimage;
# define KEXEC_ARCH KEXEC_ARCH_X86_64
#endif
-/* Memory to backup during crash kdump */
-#define KEXEC_BACKUP_SRC_START (0UL)
-#define KEXEC_BACKUP_SRC_END (640 * 1024UL - 1) /* 640K */
-
/*
* This function is responsible for capturing register states if coming
* via panic otherwise just fix up the ss and sp if coming via kernel
@@ -154,12 +150,6 @@ struct kimage_arch {
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
- /* Details of backup region */
- unsigned long backup_src_start;
- unsigned long backup_src_sz;
-
- /* Physical address of backup segment */
- unsigned long backup_load_addr;
/* Core ELF header buffer */
void *elf_headers;
diff --git a/arch/x86/include/asm/purgatory.h b/arch/x86/include/asm/purgatory.h
index 92c34e517da1..5528e9325049 100644
--- a/arch/x86/include/asm/purgatory.h
+++ b/arch/x86/include/asm/purgatory.h
@@ -6,16 +6,6 @@
#include <linux/purgatory.h>
extern void purgatory(void);
-/*
- * These forward declarations serve two purposes:
- *
- * 1) Make sparse happy when checking arch/purgatory
- * 2) Document that these are required to be global so the symbol
- * lookup in kexec works
- */
-extern unsigned long purgatory_backup_dest;
-extern unsigned long purgatory_backup_src;
-extern unsigned long purgatory_backup_sz;
#endif /* __ASSEMBLY__ */
#endif /* _ASM_PURGATORY_H */
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index eb651fbde92a..ef54b3ffb0f6 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -173,8 +173,6 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
#ifdef CONFIG_KEXEC_FILE
-static unsigned long crash_zero_bytes;
-
static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
{
unsigned int *nr_ranges = arg;
@@ -217,6 +215,11 @@ static int elf_header_exclude_ranges(struct crash_mem *cmem)
{
int ret = 0;
+ /* Exclude the low 1MiB because it is always reserved */
+ ret = crash_exclude_mem_range(cmem, 0, 1<<20);
+ if (ret)
+ return ret;
+
/* Exclude crashkernel region */
ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
if (ret)
@@ -246,9 +249,7 @@ static int prepare_elf_headers(struct kimage *image, void **addr,
unsigned long *sz)
{
struct crash_mem *cmem;
- Elf64_Ehdr *ehdr;
- Elf64_Phdr *phdr;
- int ret, i;
+ int ret;
cmem = fill_up_crash_elf_data();
if (!cmem)
@@ -267,22 +268,7 @@ static int prepare_elf_headers(struct kimage *image, void **addr,
/* By default prepare 64bit headers */
ret = crash_prepare_elf64_headers(cmem,
IS_ENABLED(CONFIG_X86_64), addr, sz);
- if (ret)
- goto out;
- /*
- * If a range matches backup region, adjust offset to backup
- * segment.
- */
- ehdr = (Elf64_Ehdr *)*addr;
- phdr = (Elf64_Phdr *)(ehdr + 1);
- for (i = 0; i < ehdr->e_phnum; phdr++, i++)
- if (phdr->p_type == PT_LOAD &&
- phdr->p_paddr == image->arch.backup_src_start &&
- phdr->p_memsz == image->arch.backup_src_sz) {
- phdr->p_offset = image->arch.backup_load_addr;
- break;
- }
out:
vfree(cmem);
return ret;
@@ -321,19 +307,11 @@ static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
unsigned long long mend)
{
unsigned long start, end;
- int ret = 0;
cmem->ranges[0].start = mstart;
cmem->ranges[0].end = mend;
cmem->nr_ranges = 1;
- /* Exclude Backup region */
- start = image->arch.backup_load_addr;
- end = start + image->arch.backup_src_sz - 1;
- ret = crash_exclude_mem_range(cmem, start, end);
- if (ret)
- return ret;
-
/* Exclude elf header region */
start = image->arch.elf_load_addr;
end = start + image->arch.elf_headers_sz - 1;
@@ -356,11 +334,11 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
memset(&cmd, 0, sizeof(struct crash_memmap_data));
cmd.params = params;
- /* Add first 640K segment */
- ei.addr = image->arch.backup_src_start;
- ei.size = image->arch.backup_src_sz;
- ei.type = E820_TYPE_RAM;
- add_e820_entry(params, &ei);
+ /* Add the low 1MiB */
+ cmd.type = E820_TYPE_RAM;
+ flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
+ walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, (1<<20)-1, &cmd,
+ memmap_entry_callback);
/* Add ACPI tables */
cmd.type = E820_TYPE_ACPI;
@@ -409,55 +387,12 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
return ret;
}
-static int determine_backup_region(struct resource *res, void *arg)
-{
- struct kimage *image = arg;
-
- image->arch.backup_src_start = res->start;
- image->arch.backup_src_sz = resource_size(res);
-
- /* Expecting only one range for backup region */
- return 1;
-}
-
int crash_load_segments(struct kimage *image)
{
int ret;
struct kexec_buf kbuf = { .image = image, .buf_min = 0,
.buf_max = ULONG_MAX, .top_down = false };
- /*
- * Determine and load a segment for backup area. First 640K RAM
- * region is backup source
- */
-
- ret = walk_system_ram_res(KEXEC_BACKUP_SRC_START, KEXEC_BACKUP_SRC_END,
- image, determine_backup_region);
-
- /* Zero or postive return values are ok */
- if (ret < 0)
- return ret;
-
- /* Add backup segment. */
- if (image->arch.backup_src_sz) {
- kbuf.buffer = &crash_zero_bytes;
- kbuf.bufsz = sizeof(crash_zero_bytes);
- kbuf.memsz = image->arch.backup_src_sz;
- kbuf.buf_align = PAGE_SIZE;
- /*
- * Ideally there is no source for backup segment. This is
- * copied in purgatory after crash. Just add a zero filled
- * segment for now to make sure checksum logic works fine.
- */
- ret = kexec_add_buffer(&kbuf);
- if (ret)
- return ret;
- image->arch.backup_load_addr = kbuf.mem;
- pr_debug("Loaded backup region at 0x%lx backup_start=0x%lx memsz=0x%lx\n",
- image->arch.backup_load_addr,
- image->arch.backup_src_start, kbuf.memsz);
- }
-
/* Prepare elf headers and add a segment */
ret = prepare_elf_headers(image, &kbuf.buffer, &kbuf.bufsz);
if (ret)
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 5dcd438ad8f2..16e125a50b33 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -298,48 +298,6 @@ static void load_segments(void)
);
}
-#ifdef CONFIG_KEXEC_FILE
-/* Update purgatory as needed after various image segments have been prepared */
-static int arch_update_purgatory(struct kimage *image)
-{
- int ret = 0;
-
- if (!image->file_mode)
- return 0;
-
- /* Setup copying of backup region */
- if (image->type == KEXEC_TYPE_CRASH) {
- ret = kexec_purgatory_get_set_symbol(image,
- "purgatory_backup_dest",
- &image->arch.backup_load_addr,
- sizeof(image->arch.backup_load_addr), 0);
- if (ret)
- return ret;
-
- ret = kexec_purgatory_get_set_symbol(image,
- "purgatory_backup_src",
- &image->arch.backup_src_start,
- sizeof(image->arch.backup_src_start), 0);
- if (ret)
- return ret;
-
- ret = kexec_purgatory_get_set_symbol(image,
- "purgatory_backup_sz",
- &image->arch.backup_src_sz,
- sizeof(image->arch.backup_src_sz), 0);
- if (ret)
- return ret;
- }
-
- return ret;
-}
-#else /* !CONFIG_KEXEC_FILE */
-static inline int arch_update_purgatory(struct kimage *image)
-{
- return 0;
-}
-#endif /* CONFIG_KEXEC_FILE */
-
int machine_kexec_prepare(struct kimage *image)
{
unsigned long start_pgtable;
@@ -353,11 +311,6 @@ int machine_kexec_prepare(struct kimage *image)
if (result)
return result;
- /* update purgatory as needed */
- result = arch_update_purgatory(image);
- if (result)
- return result;
-
return 0;
}
diff --git a/arch/x86/purgatory/purgatory.c b/arch/x86/purgatory/purgatory.c
index 3b95410ff0f8..2961234d0795 100644
--- a/arch/x86/purgatory/purgatory.c
+++ b/arch/x86/purgatory/purgatory.c
@@ -14,28 +14,10 @@
#include "../boot/string.h"
-unsigned long purgatory_backup_dest __section(.kexec-purgatory);
-unsigned long purgatory_backup_src __section(.kexec-purgatory);
-unsigned long purgatory_backup_sz __section(.kexec-purgatory);
-
u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(.kexec-purgatory);
struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(.kexec-purgatory);
-/*
- * On x86, second kernel requries first 640K of memory to boot. Copy
- * first 640K to a backup region in reserved memory range so that second
- * kernel can use first 640K.
- */
-static int copy_backup_region(void)
-{
- if (purgatory_backup_dest) {
- memcpy((void *)purgatory_backup_dest,
- (void *)purgatory_backup_src, purgatory_backup_sz);
- }
- return 0;
-}
-
static int verify_sha256_digest(void)
{
struct kexec_sha_region *ptr, *end;
@@ -66,7 +48,6 @@ void purgatory(void)
for (;;)
;
}
- copy_backup_region();
}
/*
--
2.17.1
On Thu, Oct 17, 2019 at 05:43:47PM +0800, Lianbo Jiang wrote:
> When the crashkernel kernel command line option is specified, the
> low 1MiB memory will always be reserved, which makes that the memory
> allocated later won't fall into the low 1MiB area, thereby, it's not
> necessary to create a backup region and also no need to copy the first
> 640k content to a backup region.
>
> Currently, the code related to the backup region can be safely removed,
> so lets clean up.
>
> Signed-off-by: Lianbo Jiang <[email protected]>
> ---
> arch/x86/include/asm/kexec.h | 10 ----
> arch/x86/include/asm/purgatory.h | 10 ----
> arch/x86/kernel/crash.c | 87 ++++--------------------------
> arch/x86/kernel/machine_kexec_64.c | 47 ----------------
> arch/x86/purgatory/purgatory.c | 19 -------
> 5 files changed, 11 insertions(+), 162 deletions(-)
That's a diffstat one cannot object to nowadays. :)
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette