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authorPhilipp Rudo <prudo@linux.vnet.ibm.com>2017-09-05 12:55:23 +0300
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2018-04-16 10:10:22 +0300
commitee337f5469fd67f22d231e520ec4189ce0589d92 (patch)
tree7b2d0e72573aaca14b54520ffa2c59fbcfaac81a /arch/s390/purgatory
parente49bb0a27fa3c6ec45cc13e2102a6ec13c4ae697 (diff)
downloadlinux-ee337f5469fd67f22d231e520ec4189ce0589d92.tar.xz
s390/kexec_file: Add crash support to image loader
Add support to load a crash kernel to the image loader. This requires extending the purgatory. Signed-off-by: Philipp Rudo <prudo@linux.vnet.ibm.com> Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/purgatory')
-rw-r--r--arch/s390/purgatory/head.S185
-rw-r--r--arch/s390/purgatory/purgatory.c4
2 files changed, 188 insertions, 1 deletions
diff --git a/arch/s390/purgatory/head.S b/arch/s390/purgatory/head.S
index 8735409d0280..660c96a05a9b 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 52b92f2bf0b9..4e2beb3c29b7 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)
{