On Thu, Feb 29, 2024 at 7:47 PM Ian Lance Taylor <i...@golang.org> wrote:
>
> This patch to libbacktrace reads symbol tables from debuginfo files.
> These become another symbol table to search. This is needed if people
> use --strip-all rather than --strip-debug when adding a debuglink
> section. This fixes
> https://github.com/ianlancetaylor/libbacktrace/issues/113.
> Bootstrapped and ran libbacktrace and libgo tests on
> x86_64-pc-linux-gnu. Committed to mainline.
This introduced a bug on the PPC v1 ABI, where libbacktrace uses the
.opd section to convert from a function descriptor address to a code
address. The .opd section is missing from a debuginfo file. This
patch changes the code to use the original .opd section if it is
missing. Checked on powerpc64-linux-gnu and x86_64-pc-linux-gnu.
Committed to mainline.
Ian
PR libbacktrace/114201
* elf.c (elf_add): Add caller_opd parameter. Change all callers.
Release opd data after all recursive calls.
f692b338cd27a4e0d38fcb5af3d416cd66fbf814
diff --git a/libbacktrace/elf.c b/libbacktrace/elf.c
index 664937e1438..f4527e2477d 100644
--- a/libbacktrace/elf.c
+++ b/libbacktrace/elf.c
@@ -6501,8 +6501,9 @@ backtrace_uncompress_lzma (struct backtrace_state *state,
static int
elf_add (struct backtrace_state *state, const char *filename, int descriptor,
const unsigned char *memory, size_t memory_size,
- uintptr_t base_address, backtrace_error_callback error_callback,
- void *data, fileline *fileline_fn, int *found_sym, int *found_dwarf,
+ uintptr_t base_address, struct elf_ppc64_opd_data *caller_opd,
+ backtrace_error_callback error_callback, void *data,
+ fileline *fileline_fn, int *found_sym, int *found_dwarf,
struct dwarf_data **fileline_entry, int exe, int debuginfo,
const char *with_buildid_data, uint32_t with_buildid_size)
{
@@ -6557,6 +6558,7 @@ elf_add (struct backtrace_state *state, const char
*filename, int descriptor,
struct elf_view split_debug_view[DEBUG_MAX];
unsigned char split_debug_view_valid[DEBUG_MAX];
struct elf_ppc64_opd_data opd_data, *opd;
+ int opd_view_valid;
struct dwarf_sections dwarf_sections;
if (!debuginfo)
@@ -6584,6 +6586,7 @@ elf_add (struct backtrace_state *state, const char
*filename, int descriptor,
debug_view_valid = 0;
memset (&split_debug_view_valid[0], 0, sizeof split_debug_view_valid);
opd = NULL;
+ opd_view_valid = 0;
if (!elf_get_view (state, descriptor, memory, memory_size, 0, sizeof ehdr,
error_callback, data, &ehdr_view))
@@ -6867,9 +6870,15 @@ elf_add (struct backtrace_state *state, const char
*filename, int descriptor,
opd->addr = shdr->sh_addr;
opd->data = (const char *) opd_data.view.view.data;
opd->size = shdr->sh_size;
+ opd_view_valid = 1;
}
}
+ // A debuginfo file may not have a useful .opd section, but we can use the
+ // one from the original executable.
+ if (opd == NULL)
+ opd = caller_opd;
+
if (symtab_shndx == 0)
symtab_shndx = dynsym_shndx;
if (symtab_shndx != 0)
@@ -6948,9 +6957,9 @@ elf_add (struct backtrace_state *state, const char
*filename, int descriptor,
elf_release_view (state, &debuglink_view, error_callback, data);
if (debugaltlink_view_valid)
elf_release_view (state, &debugaltlink_view, error_callback, data);
- ret = elf_add (state, "", d, NULL, 0, base_address, error_callback,
- data, fileline_fn, found_sym, found_dwarf, NULL, 0,
- 1, NULL, 0);
+ ret = elf_add (state, "", d, NULL, 0, base_address, opd,
+ error_callback, data, fileline_fn, found_sym,
+ found_dwarf, NULL, 0, 1, NULL, 0);
if (ret < 0)
backtrace_close (d, error_callback, data);
else if (descriptor >= 0)
@@ -6965,12 +6974,6 @@ elf_add (struct backtrace_state *state, const char
*filename, int descriptor,
buildid_view_valid = 0;
}
- if (opd)
- {
- elf_release_view (state, &opd->view, error_callback, data);
- opd = NULL;
- }
-
if (debuglink_name != NULL)
{
int d;
@@ -6985,9 +6988,9 @@ elf_add (struct backtrace_state *state, const char
*filename, int descriptor,
elf_release_view (state, &debuglink_view, error_callback, data);
if (debugaltlink_view_valid)
elf_release_view (state, &debugaltlink_view, error_callback, data);
- ret = elf_add (state, "", d, NULL, 0, base_address, error_callback,
- data, fileline_fn, found_sym, found_dwarf, NULL, 0,
- 1, NULL, 0);
+ ret = elf_add (state, "", d, NULL, 0, base_address, opd,
+ error_callback, data, fileline_fn, found_sym,
+ found_dwarf, NULL, 0, 1, NULL, 0);
if (ret < 0)
backtrace_close (d, error_callback, data);
else if (descriptor >= 0)
@@ -7013,7 +7016,7 @@ elf_add (struct backtrace_state *state, const char
*filename, int descriptor,
{
int ret;
- ret = elf_add (state, filename, d, NULL, 0, base_address,
+ ret = elf_add (state, filename, d, NULL, 0, base_address, opd,
error_callback, data, fileline_fn, found_sym,
found_dwarf, &fileline_altlink, 0, 1,
debugaltlink_buildid_data, debugaltlink_buildid_size);
@@ -7050,7 +7053,7 @@ elf_add (struct backtrace_state *state, const char
*filename, int descriptor,
if (ret)
{
ret = elf_add (state, filename, -1, gnu_debugdata_uncompressed,
- gnu_debugdata_uncompressed_size, base_address,
+ gnu_debugdata_uncompressed_size, base_address, opd,
error_callback, data, fileline_fn, found_sym,
found_dwarf, NULL, 0, 0, NULL, 0);
if (ret >= 0 && descriptor >= 0)
@@ -7059,6 +7062,13 @@ elf_add (struct backtrace_state *state, const char
*filename, int descriptor,
}
}
+ if (opd_view_valid)
+ {
+ elf_release_view (state, &opd->view, error_callback, data);
+ opd_view_valid = 0;
+ opd = NULL;
+ }
+
/* Read all the debug sections in a single view, since they are
probably adjacent in the file. If any of sections are
uncompressed, we never release this view. */
@@ -7305,7 +7315,7 @@ elf_add (struct backtrace_state *state, const char
*filename, int descriptor,
if (split_debug_view_valid[i])
elf_release_view (state, &split_debug_view[i], error_callback, data);
}
- if (opd)
+ if (opd_view_valid)
elf_release_view (state, &opd->view, error_callback, data);
if (descriptor >= 0)
backtrace_close (descriptor, error_callback, data);
@@ -7369,7 +7379,7 @@ phdr_callback (struct dl_phdr_info *info, size_t size
ATTRIBUTE_UNUSED,
return 0;
}
- if (elf_add (pd->state, filename, descriptor, NULL, 0, info->dlpi_addr,
+ if (elf_add (pd->state, filename, descriptor, NULL, 0, info->dlpi_addr, NULL,
pd->error_callback, pd->data, &elf_fileline_fn, pd->found_sym,
&found_dwarf, NULL, 0, 0, NULL, 0))
{
@@ -7398,9 +7408,9 @@ backtrace_initialize (struct backtrace_state *state,
const char *filename,
fileline elf_fileline_fn = elf_nodebug;
struct phdr_data pd;
- ret = elf_add (state, filename, descriptor, NULL, 0, 0, error_callback, data,
- &elf_fileline_fn, &found_sym, &found_dwarf, NULL, 1, 0, NULL,
- 0);
+ ret = elf_add (state, filename, descriptor, NULL, 0, 0, NULL, error_callback,
+ data, &elf_fileline_fn, &found_sym, &found_dwarf, NULL, 1, 0,
+ NULL, 0);
if (!ret)
return 0;
