[PATCH 16/17] s390/kexec_file: Add crash support to image loader
Philipp Rudo
prudo at linux.vnet.ibm.com
Mon Feb 12 02:07:53 PST 2018
Add support to load a crash kernel to the image loader. This requires
extending the purgatory.
Signed-off-by: Philipp Rudo <prudo at linux.vnet.ibm.com>
Reviewed-by: Martin Schwidefsky <schwidefsky at de.ibm.com>
---
arch/s390/kernel/kexec_image.c | 6 +-
arch/s390/kernel/machine_kexec_file.c | 45 ++++++++-
arch/s390/purgatory/head.S | 185 +++++++++++++++++++++++++++++++++-
arch/s390/purgatory/purgatory.c | 4 +
4 files changed, 234 insertions(+), 6 deletions(-)
diff --git a/arch/s390/kernel/kexec_image.c b/arch/s390/kernel/kexec_image.c
index 83cf5a9be3a4..60e03f7048b9 100644
--- a/arch/s390/kernel/kexec_image.c
+++ b/arch/s390/kernel/kexec_image.c
@@ -25,6 +25,8 @@ static int kexec_file_add_image_kernel(struct kimage *image,
buf.bufsz = kernel_len - STARTUP_NORMAL_OFFSET;
buf.mem = STARTUP_NORMAL_OFFSET;
+ if (image->type == KEXEC_TYPE_CRASH)
+ buf.mem += crashk_res.start;
buf.memsz = buf.bufsz;
ret = kexec_add_buffer(&buf);
@@ -43,10 +45,6 @@ static void *s390_image_load(struct kimage *image,
struct s390_load_data data = {0};
int ret;
- /* We don't support crash kernels yet. */
- if (image->type == KEXEC_TYPE_CRASH)
- return ERR_PTR(-ENOTSUPP);
-
ret = kexec_file_add_image_kernel(image, &data, kernel, kernel_len);
if (ret)
return ERR_PTR(ret);
diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
index 052640220361..050ceab746ec 100644
--- a/arch/s390/kernel/machine_kexec_file.c
+++ b/arch/s390/kernel/machine_kexec_file.c
@@ -28,6 +28,14 @@ void kexec_file_update_kernel(struct kimage *image,
memcpy(data->kernel_buf + COMMAND_LINE_OFFSET,
image->cmdline_buf, image->cmdline_buf_len);
+ if (image->type == KEXEC_TYPE_CRASH) {
+ loc = (unsigned long *)(data->kernel_buf + OLDMEM_BASE_OFFSET);
+ *loc = crashk_res.start;
+
+ loc = (unsigned long *)(data->kernel_buf + OLDMEM_SIZE_OFFSET);
+ *loc = crashk_res.end - crashk_res.start + 1;
+ }
+
if (image->initrd_buf) {
loc = (unsigned long *)(data->kernel_buf + INITRD_START_OFFSET);
*loc = data->initrd_load_addr;
@@ -42,9 +50,40 @@ static int kexec_file_update_purgatory(struct kimage *image)
u64 entry, type;
int ret;
- entry = STARTUP_NORMAL_OFFSET;
+ if (image->type == KEXEC_TYPE_CRASH) {
+ entry = STARTUP_KDUMP_OFFSET;
+ type = KEXEC_TYPE_CRASH;
+ } else {
+ entry = STARTUP_NORMAL_OFFSET;
+ type = KEXEC_TYPE_DEFAULT;
+ }
+
ret = kexec_purgatory_get_set_symbol(image, "kernel_entry", &entry,
sizeof(entry), false);
+ if (ret)
+ return ret;
+
+ ret = kexec_purgatory_get_set_symbol(image, "kernel_type", &type,
+ sizeof(type), false);
+ if (ret)
+ return ret;
+
+ if (image->type == KEXEC_TYPE_CRASH) {
+ u64 crash_size;
+
+ ret = kexec_purgatory_get_set_symbol(image, "crash_start",
+ &crashk_res.start,
+ sizeof(crashk_res.start),
+ false);
+ if (ret)
+ return ret;
+
+ crash_size = crashk_res.end - crashk_res.start + 1;
+ ret = kexec_purgatory_get_set_symbol(image, "crash_size",
+ &crash_size,
+ sizeof(crash_size),
+ false);
+ }
return ret;
}
@@ -57,6 +96,8 @@ int kexec_file_add_purgatory(struct kimage *image, struct s390_load_data *data)
data->memsz = ALIGN(data->memsz, PAGE_SIZE);
buf.mem = data->memsz;
+ if (image->type == KEXEC_TYPE_CRASH)
+ buf.mem += crashk_res.start;
ret = kexec_load_purgatory(image, &buf);
if (ret)
@@ -79,6 +120,8 @@ int kexec_file_add_initrd(struct kimage *image, struct s390_load_data *data,
data->memsz = ALIGN(data->memsz, PAGE_SIZE);
buf.mem = data->memsz;
+ if (image->type == KEXEC_TYPE_CRASH)
+ buf.mem += crashk_res.start;
buf.memsz = buf.bufsz;
data->initrd_load_addr = buf.mem;
diff --git a/arch/s390/purgatory/head.S b/arch/s390/purgatory/head.S
index 8735409d0280..6bfb13aa3f42 100644
--- a/arch/s390/purgatory/head.S
+++ b/arch/s390/purgatory/head.S
@@ -15,8 +15,52 @@
/* The purgatory is the code running between two kernels. It's main purpose
* is to verify that the next kernel was not corrupted after load and to
* start it.
+ *
+ * If the next kernel is a crash kernel there are some peculiarities to
+ * consider:
+ *
+ * First the purgatory is called twice. Once only to verify the
+ * sha digest. So if the crash kernel got corrupted the old kernel can try
+ * to trigger a stand-alone dumper. And once to actually load the crash kernel.
+ *
+ * Second the purgatory also has to swap the crash memory region with its
+ * destination at address 0. As the purgatory is part of crash memory this
+ * requires some finesse. The tactic here is that the purgatory first copies
+ * itself to the end of the destination and then swaps the rest of the
+ * memory running from there.
*/
+#define bufsz purgatory_end-stack
+
+.macro MEMCPY dst,src,len
+ lgr %r0,\dst
+ lgr %r1,\len
+ lgr %r2,\src
+ lgr %r3,\len
+
+20: mvcle %r0,%r2,0
+ jo 20b
+.endm
+
+.macro MEMSWAP dst,src,buf,len
+10: cghi \len,bufsz
+ jh 11f
+ lgr %r4,\len
+ j 12f
+11: lghi %r4,bufsz
+
+12: MEMCPY \buf,\dst,%r4
+ MEMCPY \dst,\src,%r4
+ MEMCPY \src,\buf,%r4
+
+ agr \dst,%r4
+ agr \src,%r4
+ sgr \len,%r4
+
+ cghi \len,0
+ jh 10b
+.endm
+
.macro START_NEXT_KERNEL base
lg %r4,kernel_entry-\base(%r13)
lg %r5,load_psw_mask-\base(%r13)
@@ -47,18 +91,144 @@ ENTRY(purgatory_start)
larl %r15,purgatory_end
aghi %r15,-160
+ /* If the next kernel is KEXEC_TYPE_CRASH the purgatory is called
+ * directly with a flag passed in %r2 whether the purgatory shall do
+ * checksum verification only (%r2 = 0 -> verification only).
+ *
+ * Check now and preserve over C function call by storing in
+ * %r10 whith
+ * 1 -> checksum verification only
+ * 0 -> load new kernel
+ */
+ lghi %r10,0
+ lg %r11,kernel_type-.base_crash(%r13)
+ cghi %r11,1 /* KEXEC_TYPE_CRASH */
+ jne .do_checksum_verification
+ cghi %r2,0 /* checksum verification only */
+ jne .do_checksum_verification
+ lghi %r10,1
+
.do_checksum_verification:
brasl %r14,verify_sha256_digest
+ cghi %r10,1 /* checksum verification only */
+ je .return_old_kernel
cghi %r2,0 /* checksum match */
jne .disabled_wait
+ /* If the next kernel is a crash kernel the purgatory has to swap
+ * the mem regions first.
+ */
+ cghi %r11,1 /* KEXEC_TYPE_CRASH */
+ je .start_crash_kernel
+
/* start normal kernel */
START_NEXT_KERNEL .base_crash
+.return_old_kernel:
+ lmg %r6,%r15,gprregs-.base_crash(%r13)
+ br %r14
+
.disabled_wait:
lpswe disabled_wait_psw-.base_crash(%r13)
+.start_crash_kernel:
+ /* Location of purgatory_start in crash memory */
+ lgr %r8,%r13
+ aghi %r8,-(.base_crash-purgatory_start)
+
+ /* Destination for this code i.e. end of memory to be swapped. */
+ lg %r9,crash_size-.base_crash(%r13)
+ aghi %r9,-(purgatory_end-purgatory_start)
+
+ /* Destination in crash memory, i.e. same as r9 but in crash memory. */
+ lg %r10,crash_start-.base_crash(%r13)
+ agr %r10,%r9
+
+ /* Buffer location (in crash memory) and size. As the purgatory is
+ * behind the point of no return it can re-use the stack as buffer.
+ */
+ lghi %r11,bufsz
+ larl %r12,stack
+
+ MEMCPY %r12,%r9,%r11 /* dst -> (crash) buf */
+ MEMCPY %r9,%r8,%r11 /* self -> dst */
+
+ /* Jump to new location. */
+ lgr %r7,%r9
+ aghi %r7,.jump_to_dst-purgatory_start
+ br %r7
+
+.jump_to_dst:
+ basr %r13,0
+.base_dst:
+
+ /* clear buffer */
+ MEMCPY %r12,%r10,%r11 /* (crash) buf -> (crash) dst */
+
+ /* Load new buffer location after jump */
+ larl %r7,stack
+ aghi %r10,stack-purgatory_start
+ MEMCPY %r10,%r7,%r11 /* (new) buf -> (crash) buf */
+
+ /* Now the code is set up to run from its designated location. Start
+ * swapping the rest of crash memory now.
+ *
+ * The registers will be used as follow:
+ *
+ * %r0-%r4 reserved for macros defined above
+ * %r5-%r6 tmp registers
+ * %r7 pointer to current struct sha region
+ * %r8 index to iterate over all sha regions
+ * %r9 pointer in crash memory
+ * %r10 pointer in old kernel
+ * %r11 total size (still) to be moved
+ * %r12 pointer to buffer
+ */
+ lgr %r12,%r7
+ lgr %r11,%r9
+ lghi %r10,0
+ lg %r9,crash_start-.base_dst(%r13)
+ lghi %r8,16 /* KEXEC_SEGMENTS_MAX */
+ larl %r7,purgatory_sha_regions
+
+ j .loop_first
+
+ /* Loop over all purgatory_sha_regions. */
+.loop_next:
+ aghi %r8,-1
+ cghi %r8,0
+ je .loop_out
+
+ aghi %r7,__KEXEC_SHA_REGION_SIZE
+
+.loop_first:
+ lg %r5,__KEXEC_SHA_REGION_START(%r7)
+ cghi %r5,0
+ je .loop_next
+
+ /* Copy [end last sha region, start current sha region) */
+ /* Note: kexec_sha_region->start points in crash memory */
+ sgr %r5,%r9
+ MEMCPY %r9,%r10,%r5
+
+ agr %r9,%r5
+ agr %r10,%r5
+ sgr %r11,%r5
+
+ /* Swap sha region */
+ lg %r6,__KEXEC_SHA_REGION_LEN(%r7)
+ MEMSWAP %r9,%r10,%r12,%r6
+ sg %r11,__KEXEC_SHA_REGION_LEN(%r7)
+ j .loop_next
+
+.loop_out:
+ /* Copy rest of crash memory */
+ MEMCPY %r9,%r10,%r11
+
+ /* start crash kernel */
+ START_NEXT_KERNEL .base_dst
+
load_psw_mask:
.long 0x00080000,0x80000000
@@ -89,8 +259,21 @@ kernel_entry:
.global kernel_entry
.quad 0
+kernel_type:
+ .global kernel_type
+ .quad 0
+
+crash_start:
+ .global crash_start
+ .quad 0
+
+crash_size:
+ .global crash_size
+ .quad 0
+
.align PAGE_SIZE
stack:
- .skip PAGE_SIZE
+ /* The buffer to move this code must be as big as the code. */
+ .skip stack-purgatory_start
.align PAGE_SIZE
purgatory_end:
diff --git a/arch/s390/purgatory/purgatory.c b/arch/s390/purgatory/purgatory.c
index fec67b58b8be..67ded81e0430 100644
--- a/arch/s390/purgatory/purgatory.c
+++ b/arch/s390/purgatory/purgatory.c
@@ -16,6 +16,10 @@ struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX];
u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE];
u64 kernel_entry;
+u64 kernel_type;
+
+u64 crash_start;
+u64 crash_size;
int verify_sha256_digest(void)
{
--
2.13.5
More information about the kexec
mailing list