Centralize gnu_debuglink logic in elfxx. Remove previous duplicated logic
from Gfind_proc_info and os-linux.
Logic is roughly the same as previous load_debug_frame, but uses VLAs
instead of malloc.
```
src/dwarf/Gfind_proc_info-lsb.c:536:16: warning: 'eh_frame' may be used uninitialized in this function [-Wmaybe-uninitialized]
Elf_W (Addr) eh_frame;
^
```
Introduced-in: 25413c729a
Improves support for binaries missing the GNU_EH_FRAME segment
(.eh_frame_hdr section) by adding a function
'dwarf_find_eh_frame_section' that can create a synthetic one.
This fixes GCC 4.9.3 warnings (Linux/mipsel):
dwarf/Gfind_proc_info-lsb.c: In function 'locate_debug_info':
dwarf/Gfind_proc_info-lsb.c:244:23: warning: 'mi.buf_end' may be used
uninitialized in this function [-Wmaybe-uninitialized]
struct map_iterator mi;
^
dwarf/Gfind_proc_info-lsb.c:244:23: warning: 'mi.buf' may be used
uninitialized in this function [-Wmaybe-uninitialized]
In file included from dwarf/Gfind_proc_info-lsb.c:46:0:
./os-linux.h:292:27: warning: 'mi.buf_size' may be used uninitialized in
this function [-Wmaybe-uninitialized]
munmap (mi->buf_end - mi->buf_size, mi->buf_size);
^
dwarf/Gfind_proc_info-lsb.c:244:23: note: 'mi.buf_size' was declared here
struct map_iterator mi;
^
By default, the start_ip_offset in libunwind's table_entry struct is
relative to the unw_dyn_info_t's segbase. This presents a problem
for us in conjunction with using LLVM's MCJIT because it likes to
spread text sections and the corresponding eh_frame sections quite
far apart. This represents my attempt to support this use case in the
simplest manner that is backwards compatible, by adding a new format
kind (UNW_INFO_FORMAT_REMOTE_TABLE2) that indicates that the
`start_ip_offset` should be interpreted as relative to `start_ip`
rather than segbase.
Due to a bug in the gold linker[1], the .eh_frame and .eh_frame_hdr
sections contains garbage. When dwarf_extract_proc_info_from_fde tried
to look up the begin of the CIE subsection, it would underflow the
.eh_frame segment, resulting in a crash[2].
This patch avoids that crash by checking whether the CIE pointer is
located after the begin of the .eh_frame section. The variable "base"
was misused in various places as a boolean (decode as .debug_frame or
decode as .eh_frame). These instances have been renamed to
is_debug_frame where applicable.
Tested on Linux x86_64.
[1]: https://sourceware.org/bugzilla/show_bug.cgi?id=17639
[2]: http://lists.nongnu.org/archive/html/libunwind-devel/2014-11/msg00009.html
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
This change adds some special cases to allow libunwind to compile
for QNX.
* QNX's copy of <elf.h> and <link.h> reside in sys/ instead. To deal
with this, an AC_CHECK_HEADERS() was added to check for the files
in both locations.
* Similarly, QNX does not have <endian.h>. In cases where the file is
not found, logic was added to refer to QNX-specific macros to determine
endianness.
* The QCC compiler, which is a wrapper around GCC, cannot handle some
standard GCC options. Therefore, logic was added to check for QCC,
and when it is found, to suppress the use of -lgcc, and to express the
option -nostartfiles as -Wc,-nostartfiles instead, which is correctly
passed on to the underlying GCC.
* Finally, the support file os-qnx.c was added, patterned after the existing
os-*.c files. Only local image lookup is currently supported (see the
comments for more information), but this is sufficient for QNX, since
ptrace is not supported there anyway, and that is the only case where the
function is required to do remote image lookup.
Change-Id: Ie7934f94a7317bdde59335f2acd4c3a97c0384c1
Just pass potentially NULL pointers to free() in the error path in
load_debug_frame(). Saved 40 bytes of code in libunwind.so on ARM -O2
thumb build at the expense of slightly slower execution.
Since the dl_iterate_phdr is required for local unwinding only the use of
struct dl_phdr_info can be eliminated in case libunwind gets compiled for
remote unwinding. This enhances libunwinds portability to targets that
don't provide any dl_iterate_phdr functionality.
Signed-off-by: Ken Werner <ken.werner@linaro.org>
Exclude <link.h> because it is only required for local unwinding when
iterating over the program headers.
Have the following DWARF related functions available in case of
UNW_REMOTE_ONLY because they are used by libunwind-ptrace:
dwarf_find_debug_frame
locate_debug_info
find_binary_for_address
load_debug_frame
debug_frame_tab_new
debug_frame_tab_append
debug_frame_tab_shrink
debug_frame_tab_compare
Signed-off-by: Ken Werner <ken.werner@linaro.org>
Rename the dwarf dl_iterate_phdr callback routine and the callback_data
structure to dwarf_callback and dwarf_callback_data. Make it available
within libunwind by declaring the two at the dwarf.h header file.
Signed-off-by: Ken Werner <ken.werner@linaro.org>
Current implementation fails to find separate debug symbols when
.gnu_debuglink is set to the same name of the target ELF basename
(e.g. "libc.so.6" for /lib/libc.so.6). This patch fixes this by ignoring
separate debug files that contain a .gnu_debuglink section.
It also fixes a small typo in a related Debug() line.
Signed-off-by: Andris Zeila <andris.zeila@accenture.com>
Currently, libunwind allocates several PATH_MAX entries on stack, while
trying to find a binary via /proc/.../maps.
However stack space may be at premium (especially when sigaltstack is used),
and PATH_MAX on Linux is 4096, while SIGSTKSZ is only 8192 on x86.
Attached patch eliminates multiple PATH_MAX stack allocations, and simplifies
code in maps_next, at the cost of being unable to do anything if we can't
mmap one page. It appears to me that under such low-memory conditions,
libunwind will fail shortly elsewhere anyway.
This patch also disables more of debug_frame-handling code when
CONFIG_DEBUG_FRAME is undefined.
Tested on Linux/x86_64 with and without CONFIG_DEBUG_FRAME, no regressions.
2004/11/17 02:43:39-08:00 mostang.com!davidm
(struct callback_data): New structure.
(linear_search): New function.
(callback): Convert to getting auxiliary info passed via a pointer to
a callback_data structure, rather than an unw_dyn_info_t
structure.
Keep track of the maximum load address in max_load_addr.
If an object doesn't have a binary search-table, fall back
on a linear search.
(dwarf_find_proc_info): Fill in callback-data structure before calling
dl_iterate_phdr(). Upon returning, check whether
cb_data.single_fde is set and, if so, return directly, without
searching the DWARF unwind-table.
(dwarf_search_unwind_table): Adjust for renaming of
dwarf_parse_fde() to dwarf_extract_proc_info_from_fde().
If IP doesn't fall into the IP-range of the FDE-entry found
by the search, return UNW_ENOINFO.
(Logical change 1.290)
Drop DWARF-parsing debug prints from level 16 to 15.
(struct table_entry): Change member types from unw_word_t to int32_t. The members
need to be of a signed type and forcing them to 32 bits makes the type
work for both 32-bit and 64-bit executables (up to 4GB of text-size).
(callback): Only allow search tables which have 32-bit members.
Fix initialization of di->u.rti.table_len to express table-length as a count
of unw_word_t, as it's defined to be (we get lucky here: even with 32-bit
members, each table-entry contains two members so we're guaranteed that the
table has a size that is an integer-multiple of unw_word_t even on 64-bit
platforms).
(lookup): Change type of "rel_ip" from unw_word_t to int32_t. Simplify the
code a bit.
(remote_read): Delete.
(remote_lookup): Use dwarf_reads32() instead of remote_read() to read out table
members. Simplify code a bit.
(Logical change 1.248)
