kgdb: correctly map sections to addresses in elf object modules (amd64)

Unlike for modules with dso type, in elf object modules all the sections
have virtual address of zero.  So, it is insufficient to add module base
address to section virtual address (as recorded in section header) to
get section address in kernel memory.
Instead, we should apply the same calculations that are performed by
kernel loaders (in boot code and in kernel) when they lay out sections
in memory.

Discussed with:	jhb, np
MFC after:	3 weeks

1 files changed, 28 insertions, 6 deletions

diff --git a/gnu/usr.bin/gdb/kgdb/kld.c b/gnu/usr.bin/gdb/kgdb/kld.c
index 716a67c..d5ba20a 100644
--- a/gnu/usr.bin/gdb/kgdb/kld.c
+++ b/gnu/usr.bin/gdb/kgdb/kld.c
@@ -198,12 +198,32 @@ find_kld_address (char *arg, CORE_ADDR *address)
 }
 
 static void
+adjust_section_address (struct section_table *sec, CORE_ADDR *curr_base)
+{
+	struct bfd_section *asect = sec->the_bfd_section;
+	bfd *abfd = sec->bfd;
+
+	if ((abfd->flags & (EXEC_P | DYNAMIC)) != 0) {
+		sec->addr += *curr_base;
+		sec->endaddr += *curr_base;
+		return;
+	}
+
+	*curr_base = align_power(*curr_base,
+	    bfd_get_section_alignment(abfd, asect));
+	sec->addr = *curr_base;
+	sec->endaddr = sec->addr + bfd_section_size(abfd, asect);
+	*curr_base = sec->endaddr;
+}
+
+static void
 load_kld (char *path, CORE_ADDR base_addr, int from_tty)
 {
 	struct section_addr_info *sap;
 	struct section_table *sections = NULL, *sections_end = NULL, *s;
 	struct cleanup *cleanup;
 	bfd *bfd;
+	CORE_ADDR curr_addr;
 	int i;
 
 	/* Open the kld. */
@@ -224,10 +244,9 @@ load_kld (char *path, CORE_ADDR base_addr, int from_tty)
 	if (build_section_table (bfd, &sections, &sections_end))
 		error("\"%s\": can't find file sections", path);
 	cleanup = make_cleanup(xfree, sections);
-	for (s = sections; s < sections_end; s++) {
-		s->addr += base_addr;
-		s->endaddr += base_addr;
-	}
+	curr_addr = base_addr;
+	for (s = sections; s < sections_end; s++)
+		adjust_section_address(s, &curr_addr);
 
 	/* Build a section addr info to pass to symbol_file_add(). */
 	sap = build_section_addr_info_from_section_table (sections,
@@ -284,9 +303,12 @@ kgdb_add_kld_cmd (char *arg, int from_tty)
 static void
 kld_relocate_section_addresses (struct so_list *so, struct section_table *sec)
 {
+	static CORE_ADDR curr_addr;
+
+	if (sec == so->sections)
+		curr_addr = so->lm_info->base_address;
 
-	sec->addr += so->lm_info->base_address;
-	sec->endaddr += so->lm_info->base_address;
+	adjust_section_address(sec, &curr_addr);
 }
 
 static void