[PATCH 2/3] Dwarf: load and parse the debug info of different target address sizes
Jean Pihet
jean.pihet at linaro.org
Mon Jan 20 16:22:01 EST 2014
When in compat mode, load and parse the dwarf debug info accordingly.
Tested dwarf local unwinding on ARMv8 (aka AARCH64) with ARMv7 and
ARMv8 binaries.
Signed-off-by: Jean Pihet <jean.pihet at linaro.org>
---
src/dwarf/Gfde.c | 25 ++++--
src/dwarf/Gfind_proc_info-lsb.c | 194 +++++++++++++++++++++++++++++++---------
2 files changed, 170 insertions(+), 49 deletions(-)
diff --git a/src/dwarf/Gfde.c b/src/dwarf/Gfde.c
index 8659624..81959d1 100644
--- a/src/dwarf/Gfde.c
+++ b/src/dwarf/Gfde.c
@@ -59,14 +59,23 @@ parse_cie (unw_addr_space_t as, unw_accessors_t *a, unw_word_t addr,
/* Pick appropriate default for FDE-encoding. DWARF spec says
start-IP (initial_location) and the code-size (address_range) are
"address-unit sized constants". The `R' augmentation can be used
- to override this, but by default, we pick an address-sized unit
- for fde_encoding. */
- switch (dwarf_addr_size (as))
- {
- case 4: fde_encoding = DW_EH_PE_udata4; break;
- case 8: fde_encoding = DW_EH_PE_udata8; break;
- default: fde_encoding = DW_EH_PE_omit; break;
- }
+ to override this, but by default, we pick the target binary address
+ size unit for fde_encoding. */
+ switch (as->target_addr_size)
+ {
+ /* If defined at binary load time (e.g. from the ELF format) */
+ case TARGET_ADDR_SIZE_32: fde_encoding = DW_EH_PE_udata4; break;
+ case TARGET_ADDR_SIZE_64: fde_encoding = DW_EH_PE_udata8; break;
+ /* If not defined, use the current address size unit */
+ case TARGET_ADDR_SIZE_DEFAULT:
+ default:
+ switch (dwarf_addr_size (as))
+ {
+ case 4: fde_encoding = DW_EH_PE_udata4; break;
+ case 8: fde_encoding = DW_EH_PE_udata8; break;
+ default: fde_encoding = DW_EH_PE_omit; break;
+ }
+ }
dci->lsda_encoding = DW_EH_PE_omit;
dci->handler = 0;
diff --git a/src/dwarf/Gfind_proc_info-lsb.c b/src/dwarf/Gfind_proc_info-lsb.c
index f75bda2..8c35e58 100644
--- a/src/dwarf/Gfind_proc_info-lsb.c
+++ b/src/dwarf/Gfind_proc_info-lsb.c
@@ -81,36 +81,89 @@ linear_search (unw_addr_space_t as, unw_word_t ip,
#endif /* !UNW_REMOTE_ONLY */
#ifdef CONFIG_DEBUG_FRAME
-/* Load .debug_frame section from FILE. Allocates and returns space
- in *BUF, and sets *BUFSIZE to its size. IS_LOCAL is 1 if using the
- local process, in which case we can search the system debug file
- directory; 0 for other address spaces, in which case we do not; or
- -1 for recursive calls following .gnu_debuglink. Returns 0 on
- success, 1 on error. Succeeds even if the file contains no
- .debug_frame. */
-/* XXX: Could use mmap; but elf_map_image keeps tons mapped in. */
-
-static int
-load_debug_frame (const char *file, char **buf, size_t *bufsize, int is_local)
+static int load_debug_frame_Elf32(const char *file, FILE *f, char *linkbuf,
+ size_t *linksize, char **buf, size_t *bufsize)
{
- FILE *f;
- Elf_W (Ehdr) ehdr;
- Elf_W (Half) shstrndx;
- Elf_W (Shdr) *sec_hdrs = NULL;
+ Elf32_Ehdr ehdr;
+ Elf32_Shdr *sec_hdrs = NULL;
+ Elf32_Half shstrndx;
char *stringtab = NULL;
unsigned int i;
- size_t linksize = 0;
- char *linkbuf = NULL;
+
+ if (fseek(f, 0L, SEEK_SET))
+ goto file_error;
+ if (fread (&ehdr, sizeof(Elf32_Ehdr), 1, f) != 1)
+ goto file_error;
- *buf = NULL;
- *bufsize = 0;
+ shstrndx = ehdr.e_shstrndx;
- f = fopen (file, "r");
+ Debug (4, "opened file '%s'. Section header at offset %d\n",
+ file, (int) ehdr.e_shoff);
+
+ fseek (f, ehdr.e_shoff, SEEK_SET);
+ sec_hdrs = calloc (ehdr.e_shnum, sizeof(Elf32_Shdr));
+ if (fread (sec_hdrs, sizeof(Elf32_Shdr), ehdr.e_shnum, f) != ehdr.e_shnum)
+ goto file_error;
- if (!f)
- return 1;
+ Debug (4, "loading string table of size %zd\n",
+ sec_hdrs[shstrndx].sh_size);
+ stringtab = malloc (sec_hdrs[shstrndx].sh_size);
+ fseek (f, sec_hdrs[shstrndx].sh_offset, SEEK_SET);
+ if (fread (stringtab, 1, sec_hdrs[shstrndx].sh_size, f) != sec_hdrs[shstrndx].sh_size)
+ goto file_error;
- if (fread (&ehdr, sizeof (Elf_W (Ehdr)), 1, f) != 1)
+ for (i = 1; i < ehdr.e_shnum && *buf == NULL; i++)
+ {
+ char *secname = &stringtab[sec_hdrs[i].sh_name];
+
+ if (strcmp (secname, ".debug_frame") == 0)
+ {
+ *bufsize = sec_hdrs[i].sh_size;
+ *buf = malloc (*bufsize);
+
+ fseek (f, sec_hdrs[i].sh_offset, SEEK_SET);
+ if (fread (*buf, 1, *bufsize, f) != *bufsize)
+ goto file_error;
+
+ Debug (4, "read %zd bytes of .debug_frame from offset %d\n",
+ *bufsize, sec_hdrs[i].sh_offset);
+ }
+ else if (strcmp (secname, ".gnu_debuglink") == 0)
+ {
+ *linksize = sec_hdrs[i].sh_size;
+ linkbuf = malloc(*linksize);
+
+ fseek (f, sec_hdrs[i].sh_offset, SEEK_SET);
+ if (fread (linkbuf, 1, *linksize, f) != *linksize)
+ goto file_error;
+
+ Debug (4, "read %d bytes of .gnu_debuglink from offset %d\n",
+ (int) *linksize, sec_hdrs[i].sh_offset);
+ }
+ }
+
+ free(sec_hdrs);
+ free(stringtab);
+ return 0;
+
+file_error:
+ free(sec_hdrs);
+ free(stringtab);
+ return -1;
+}
+
+static int load_debug_frame_Elf64(const char *file, FILE *f, char *linkbuf,
+ size_t *linksize, char **buf, size_t *bufsize)
+{
+ Elf64_Ehdr ehdr;
+ Elf64_Shdr *sec_hdrs = NULL;
+ Elf64_Half shstrndx;
+ char *stringtab = NULL;
+ unsigned int i;
+
+ if (fseek(f, 0L, SEEK_SET))
+ goto file_error;
+ if (fread (&ehdr, sizeof(Elf64_Ehdr), 1, f) != 1)
goto file_error;
shstrndx = ehdr.e_shstrndx;
@@ -119,8 +172,8 @@ load_debug_frame (const char *file, char **buf, size_t *bufsize, int is_local)
file, (int) ehdr.e_shoff);
fseek (f, ehdr.e_shoff, SEEK_SET);
- sec_hdrs = calloc (ehdr.e_shnum, sizeof (Elf_W (Shdr)));
- if (fread (sec_hdrs, sizeof (Elf_W (Shdr)), ehdr.e_shnum, f) != ehdr.e_shnum)
+ sec_hdrs = calloc (ehdr.e_shnum, sizeof(Elf64_Shdr));
+ if (fread (sec_hdrs, sizeof(Elf64_Shdr), ehdr.e_shnum, f) != ehdr.e_shnum)
goto file_error;
Debug (4, "loading string table of size %zd\n",
@@ -131,7 +184,7 @@ load_debug_frame (const char *file, char **buf, size_t *bufsize, int is_local)
goto file_error;
for (i = 1; i < ehdr.e_shnum && *buf == NULL; i++)
- {
+ {
char *secname = &stringtab[sec_hdrs[i].sh_name];
if (strcmp (secname, ".debug_frame") == 0)
@@ -148,20 +201,71 @@ load_debug_frame (const char *file, char **buf, size_t *bufsize, int is_local)
}
else if (strcmp (secname, ".gnu_debuglink") == 0)
{
- linksize = sec_hdrs[i].sh_size;
- linkbuf = malloc (linksize);
+ *linksize = sec_hdrs[i].sh_size;
+ linkbuf = malloc(*linksize);
fseek (f, sec_hdrs[i].sh_offset, SEEK_SET);
- if (fread (linkbuf, 1, linksize, f) != linksize)
+ if (fread (linkbuf, 1, *linksize, f) != *linksize)
goto file_error;
- Debug (4, "read %zd bytes of .gnu_debuglink from offset %zd\n",
- linksize, sec_hdrs[i].sh_offset);
+ Debug (4, "read %d bytes of .gnu_debuglink from offset %zd\n",
+ (int) *linksize, sec_hdrs[i].sh_offset);
}
- }
+ }
+
+ free(sec_hdrs);
+ free(stringtab);
+ return 0;
+
+file_error:
+ free(sec_hdrs);
+ free(stringtab);
+ return -1;
+}
+
+/* Load .debug_frame section from FILE. Allocates and returns space
+ in *BUF, and sets *BUFSIZE to its size. IS_LOCAL is 1 if using the
+ local process, in which case we can search the system debug file
+ directory; 0 for other address spaces, in which case we do not; or
+ -1 for recursive calls following .gnu_debuglink. Returns 0 on
+ success, 1 on error. Succeeds even if the file contains no
+ .debug_frame. */
+/* XXX: Could use mmap; but elf_map_image keeps tons mapped in. */
- free (stringtab);
- free (sec_hdrs);
+static int
+load_debug_frame (const char *file, char **buf, size_t *bufsize,
+ unw_addr_space_t as, int is_local)
+{
+ FILE *f;
+ unsigned char e_ident[sizeof(((Elf32_Ehdr *)0)->e_ident)];
+ size_t linksize = 0;
+ char *linkbuf = NULL;
+
+ *buf = NULL;
+ *bufsize = 0;
+
+ f = fopen (file, "r");
+
+ if (!f)
+ return 1;
+
+ if (fread (&e_ident, sizeof(e_ident), 1, f) != 1)
+ goto file_error;
+
+ switch (e_ident[EI_CLASS]) {
+ case ELFCLASS32:
+ as->target_addr_size = TARGET_ADDR_SIZE_32;
+ load_debug_frame_Elf32(file, f, linkbuf, &linksize, buf, bufsize);
+ break;
+ case ELFCLASS64:
+ as->target_addr_size = TARGET_ADDR_SIZE_64;
+ load_debug_frame_Elf64(file, f, linkbuf, &linksize, buf, bufsize);
+ break;
+ case ELFCLASSNONE:
+ default:
+ Debug (15, "Wrong ELF class 0x%02x\n", e_ident[EI_CLASS]);
+ goto file_error;
+ }
fclose (f);
@@ -195,14 +299,14 @@ load_debug_frame (const char *file, char **buf, size_t *bufsize, int is_local)
strcpy (newname, basedir);
strcat (newname, "/");
strcat (newname, linkbuf);
- ret = load_debug_frame (newname, buf, bufsize, -1);
+ ret = load_debug_frame (newname, buf, bufsize, as, -1);
if (ret == 1)
{
strcpy (newname, basedir);
strcat (newname, "/.debug/");
strcat (newname, linkbuf);
- ret = load_debug_frame (newname, buf, bufsize, -1);
+ ret = load_debug_frame (newname, buf, bufsize, as, -1);
}
if (ret == 1 && is_local == 1)
@@ -211,20 +315,19 @@ load_debug_frame (const char *file, char **buf, size_t *bufsize, int is_local)
strcat (newname, basedir);
strcat (newname, "/");
strcat (newname, linkbuf);
- ret = load_debug_frame (newname, buf, bufsize, -1);
+ ret = load_debug_frame (newname, buf, bufsize, as, -1);
}
free (basedir);
free (newname);
}
- free (linkbuf);
+
+ free(linkbuf);
return 0;
/* An error reading image file. Release resources and return error code */
file_error:
- free(stringtab);
- free(sec_hdrs);
free(linkbuf);
fclose(f);
@@ -303,7 +406,8 @@ locate_debug_info (unw_addr_space_t as, unw_word_t addr, const char *dlname,
else
name = (char*) dlname;
- err = load_debug_frame (name, &buf, &bufsize, as == unw_local_addr_space);
+ err = load_debug_frame (name, &buf, &bufsize, as,
+ as == unw_local_addr_space);
if (!err)
{
@@ -851,6 +955,14 @@ dwarf_search_unwind_table (unw_addr_space_t as, unw_word_t ip,
#ifndef UNW_REMOTE_ONLY
struct unw_debug_frame_list *fdesc = (void *) di->u.ti.table_data;
+ /*
+ * Set the target address size as found in the loaded debug binary.
+ * Note: in case of local unwinding the caller 'as' is set to
+ * unw_local_addr_space, cf. below. Let's assign the value to
+ * the caller 'as' before changing the value of 'as'.
+ */
+ as->target_addr_size = unw_local_addr_space->target_addr_size;
+
/* UNW_INFO_FORMAT_TABLE (i.e. .debug_frame) is read from local address
space. Both the index and the unwind tables live in local memory, but
the address space to check for properties like the address size and
--
1.7.11.7
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