[PATCH] ia64: make kcore work

/proc/kcore is what you need, but it is broken on ia64 (and
has been since the dawn of time for access to region 5) because
it assumes that all kernel virtual addresses are above PAGE+AF8-OFFSET.
This isn't true on ia64, VMALLOC+AF8-START is smaller than PAGE+AF8-OFFSET.

Attached is a patch (applies to 2.4.19 and to 2.5.39) that fixes the
assumption.  After applying you'll be able to use:

        +ACM- gdb vmlinux /proc/kcore

and happily ask gdb to examine addresses in region 5.

fs/proc/kcore.c

@@ -99,6 +99,12 @@ static ssize_t read_kcore(struct file *file, char *buf, size_t count, loff_t *pp
 }
 #else /* CONFIG_KCORE_AOUT */
 
+#if VMALLOC_START < PAGE_OFFSET
+#define	KCORE_BASE	VMALLOC_START
+#else
+#define	KCORE_BASE	PAGE_OFFSET
+#endif
+
 #define roundup(x, y)  ((((x)+((y)-1))/(y))*(y))
 
 /* An ELF note in memory */
@@ -118,7 +124,7 @@ static size_t get_kcore_size(int *num_vma, size_t *elf_buflen)
 	struct vm_struct *m;
 
 	*num_vma = 0;
-	size = ((size_t)high_memory - PAGE_OFFSET + PAGE_SIZE);
+	size = ((size_t)high_memory - KCORE_BASE + PAGE_SIZE);
 	if (!vmlist) {
 		*elf_buflen = PAGE_SIZE;
 		return (size);
@@ -126,15 +132,15 @@ static size_t get_kcore_size(int *num_vma, size_t *elf_buflen)
 
 	for (m=vmlist; m; m=m->next) {
 		try = (size_t)m->addr + m->size;
-		if (try > size)
-			size = try;
+		if (try > KCORE_BASE + size)
+			size = try - KCORE_BASE;
 		*num_vma = *num_vma + 1;
 	}
 	*elf_buflen =	sizeof(struct elfhdr) + 
 			(*num_vma + 2)*sizeof(struct elf_phdr) + 
 			3 * sizeof(struct memelfnote);
 	*elf_buflen = PAGE_ALIGN(*elf_buflen);
-	return (size - PAGE_OFFSET + *elf_buflen);
+	return size + *elf_buflen;
 }
 
 
@@ -237,7 +243,7 @@ static void elf_kcore_store_hdr(char *bufp, int num_vma, int dataoff)
 	offset += sizeof(struct elf_phdr);
 	phdr->p_type	= PT_LOAD;
 	phdr->p_flags	= PF_R|PF_W|PF_X;
-	phdr->p_offset	= dataoff;
+	phdr->p_offset	= PAGE_OFFSET - KCORE_BASE + dataoff;
 	phdr->p_vaddr	= PAGE_OFFSET;
 	phdr->p_paddr	= __pa(PAGE_OFFSET);
 	phdr->p_filesz	= phdr->p_memsz = ((unsigned long)high_memory - PAGE_OFFSET);
@@ -254,7 +260,7 @@ static void elf_kcore_store_hdr(char *bufp, int num_vma, int dataoff)
 
 		phdr->p_type	= PT_LOAD;
 		phdr->p_flags	= PF_R|PF_W|PF_X;
-		phdr->p_offset	= (size_t)m->addr - PAGE_OFFSET + dataoff;
+		phdr->p_offset	= (size_t)m->addr - KCORE_BASE + dataoff;
 		phdr->p_vaddr	= (size_t)m->addr;
 		phdr->p_paddr	= __pa(m->addr);
 		phdr->p_filesz	= phdr->p_memsz	= m->size;
@@ -385,9 +391,9 @@ static ssize_t read_kcore(struct file *file, char *buffer, size_t buflen, loff_t
 	/*
 	 * Fill the remainder of the buffer from kernel VM space.
 	 * We said in the ELF header that the data which starts
-	 * at 'elf_buflen' is virtual address PAGE_OFFSET. --rmk
+	 * at 'elf_buflen' is virtual address KCORE_BASE. --rmk
 	 */
-	start = PAGE_OFFSET + (*fpos - elf_buflen);
+	start = KCORE_BASE + (*fpos - elf_buflen);
 	if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 		tsz = buflen;