[PATCH v4 2/3] s390/kdump: Use ELF header in new memory feature

[holzheu@xxxxxxxxxxxxxxxxxx (Michael Holzheu)]

This patch now exchanges the old relocate mechanism with the new
arch function call override mechanism that allows to create the ELF
core header in the 2nd kernel.

Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
---
 arch/s390/kernel/crash_dump.c | 64 ++++++++++++++++++++++++++++++-------------
 1 file changed, 45 insertions(+), 19 deletions(-)

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index f703d91..aeb1207 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -21,6 +21,9 @@
 #define PTR_SUB(x, y) (((char *) (x)) - ((unsigned long) (y)))
 #define PTR_DIFF(x, y) ((unsigned long)(((char *) (x)) - ((unsigned long) (y))))
 
+static size_t elfcorebuf_sz;
+static char *elfcorebuf;
+
 /*
  * Copy one page from "oldmem"
  *
@@ -325,14 +328,6 @@ static int get_mem_chunk_cnt(void)
 }
 
 /*
- * Relocate pointer in order to allow vmcore code access the data
- */
-static inline unsigned long relocate(unsigned long addr)
-{
-	return OLDMEM_BASE + addr;
-}
-
-/*
  * Initialize ELF loads (new kernel)
  */
 static int loads_init(Elf64_Phdr *phdr, u64 loads_offset)
@@ -383,7 +378,7 @@ static void *notes_init(Elf64_Phdr *phdr, void *ptr, u64 notes_offset)
 	ptr = nt_vmcoreinfo(ptr);
 	memset(phdr, 0, sizeof(*phdr));
 	phdr->p_type = PT_NOTE;
-	phdr->p_offset = relocate(notes_offset);
+	phdr->p_offset = notes_offset;
 	phdr->p_filesz = (unsigned long) PTR_SUB(ptr, ptr_start);
 	phdr->p_memsz = phdr->p_filesz;
 	return ptr;
@@ -392,7 +387,7 @@ static void *notes_init(Elf64_Phdr *phdr, void *ptr, u64 notes_offset)
 /*
  * Create ELF core header (new kernel)
  */
-static void s390_elf_corehdr_create(char **elfcorebuf, size_t *elfcorebuf_sz)
+static int s390_elf_corehdr_create(char **elfcorebuf, size_t *elfcorebuf_sz)
 {
 	Elf64_Phdr *phdr_notes, *phdr_loads;
 	int mem_chunk_cnt;
@@ -414,28 +409,59 @@ static void s390_elf_corehdr_create(char **elfcorebuf, size_t *elfcorebuf_sz)
 	ptr = PTR_ADD(ptr, sizeof(Elf64_Phdr) * mem_chunk_cnt);
 	/* Init notes */
 	hdr_off = PTR_DIFF(ptr, hdr);
-	ptr = notes_init(phdr_notes, ptr, ((unsigned long) hdr) + hdr_off);
+	ptr = notes_init(phdr_notes, ptr, (unsigned long) hdr + hdr_off);
 	/* Init loads */
 	hdr_off = PTR_DIFF(ptr, hdr);
-	loads_init(phdr_loads, ((unsigned long) hdr) + hdr_off);
+	loads_init(phdr_loads, hdr_off);
 	*elfcorebuf_sz = hdr_off;
-	*elfcorebuf = (void *) relocate((unsigned long) hdr);
+	*elfcorebuf = hdr;
 	BUG_ON(*elfcorebuf_sz > alloc_size);
+	return 0;
 }
 
 /*
- * Create kdump ELF core header in new kernel, if it has not been passed via
- * the "elfcorehdr" kernel parameter
+ * Return address of ELF core header (new or old memory)
  */
-static int setup_kdump_elfcorehdr(void)
+unsigned long long arch_get_crash_header(void)
 {
-	size_t elfcorebuf_sz;
-	char *elfcorebuf;
+	if (elfcorebuf)
+		return elfcorehdr_addr;
+	else
+		return __pa(elfcorebuf);
+}
 
+/*
+ * Free crash header
+ */
+void arch_free_crash_header(void)
+{
+	kfree(elfcorebuf);
+	elfcorebuf = 0;
+}
+
+/*
+ * Read from crash header (new or old memory)
+ */
+ssize_t arch_read_from_crash_header(char *buf, size_t count, u64 *ppos)
+{
+	if (elfcorebuf)
+		memcpy(buf, (void *)*ppos, count);
+	else
+		copy_from_oldmem(buf, (void *)*ppos, count);
+	*ppos += count;
+	return count;
+}
+
+/*
+ * Create kdump ELF core header in new kernel if it has not been passed via
+ * the "elfcorehdr=" kernel parameter
+ */
+static int setup_kdump_elfcorehdr(void)
+{
 	if (!OLDMEM_BASE || is_kdump_kernel())
 		return -EINVAL;
 	s390_elf_corehdr_create(&elfcorebuf, &elfcorebuf_sz);
-	elfcorehdr_addr = (unsigned long long) elfcorebuf;
+	elfcorehdr_addr = __pa(elfcorebuf);
 	elfcorehdr_size = elfcorebuf_sz;
 	return 0;
 }
-- 
1.8.1.6