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

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Message-Id: <1369394983-65360-3-git-send-email-holzheu@linux.vnet.ibm.com>
Date:	Fri, 24 May 2013 13:29:42 +0200
From:	Michael Holzheu <holzheu@...ux.vnet.ibm.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	Jan Willeke <willeke@...ibm.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	Michael Holzheu <holzheu@...ux.vnet.ibm.com>
Subject: [PATCH v4 2/3] s390/kdump: Use ELF header in new memory feature

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@...ux.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

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