s390/vmcore: use ELF header in new memory feature

Exchange 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@linux.vnet.ibm.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Jan Willeke <willeke@de.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/s390/kernel/crash_dump.c

@@ -63,6 +63,11 @@ static ssize_t copy_page_real(void *buf, void *src, size_t csize)
 	}
 }
 
+/*
+ * Pointer to ELF header in new kernel
+ */
+static void *elfcorehdr_newmem;
+
 /*
  * Copy one page from "oldmem"
  *
@@ -367,14 +372,6 @@ static int get_mem_chunk_cnt(void)
 	return cnt;
 }
 
-/*
- * 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)
  */
@@ -426,7 +423,7 @@ 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;
@@ -435,7 +432,7 @@ 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)
+int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size)
 {
 	Elf64_Phdr *phdr_notes, *phdr_loads;
 	int mem_chunk_cnt;
@@ -443,6 +440,11 @@ static void s390_elf_corehdr_create(char **elfcorebuf, size_t *elfcorebuf_sz)
 	u32 alloc_size;
 	u64 hdr_off;
 
+	if (!OLDMEM_BASE)
+		return 0;
+	/* If elfcorehdr= has been passed via cmdline, we use that one */
+	if (elfcorehdr_addr != ELFCORE_ADDR_MAX)
+		return 0;
 	mem_chunk_cnt = get_mem_chunk_cnt();
 
 	alloc_size = 0x1000 + get_cpu_cnt() * 0x300 +
@@ -460,27 +462,52 @@ static void s390_elf_corehdr_create(char **elfcorebuf, size_t *elfcorebuf_sz)
 	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);
-	*elfcorebuf_sz = hdr_off;
-	*elfcorebuf = (void *) relocate((unsigned long) hdr);
-	BUG_ON(*elfcorebuf_sz > alloc_size);
+	loads_init(phdr_loads, hdr_off);
+	*addr = (unsigned long long) hdr;
+	elfcorehdr_newmem = hdr;
+	*size = (unsigned long long) hdr_off;
+	BUG_ON(elfcorehdr_size > alloc_size);
+	return 0;
 }
 
 /*
- * Create kdump ELF core header in new kernel, if it has not been passed via
- * the "elfcorehdr" kernel parameter
+ * Free ELF core header (new kernel)
  */
-static int setup_kdump_elfcorehdr(void)
+void elfcorehdr_free(unsigned long long addr)
 {
-	size_t elfcorebuf_sz;
-	char *elfcorebuf;
-
-	if (!OLDMEM_BASE || is_kdump_kernel())
-		return -EINVAL;
-	s390_elf_corehdr_create(&elfcorebuf, &elfcorebuf_sz);
-	elfcorehdr_addr = (unsigned long long) elfcorebuf;
-	elfcorehdr_size = elfcorebuf_sz;
-	return 0;
+	if (!elfcorehdr_newmem)
+		return;
+	kfree((void *)(unsigned long)addr);
+}
+
+/*
+ * Read from ELF header
+ */
+ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
+{
+	void *src = (void *)(unsigned long)*ppos;
+
+	src = elfcorehdr_newmem ? src : src - OLDMEM_BASE;
+	memcpy(buf, src, count);
+	*ppos += count;
+	return count;
 }
 
-subsys_initcall(setup_kdump_elfcorehdr);
+/*
+ * Read from ELF notes data
+ */
+ssize_t elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
+{
+	void *src = (void *)(unsigned long)*ppos;
+	int rc;
+
+	if (elfcorehdr_newmem) {
+		memcpy(buf, src, count);
+	} else {
+		rc = copy_from_oldmem(buf, src, count);
+		if (rc)
+			return rc;
+	}
+	*ppos += count;
+	return count;
+}