Summary:
This is the first in a series of patches to enable LLDB debugging of
WebAssembly targets.
Current versions of Clang emit (partial) DWARF debug information in WebAssembly
modules and we can leverage this debug information to give LLDB the ability to
do source-level debugging of Wasm code that runs in a WebAssembly engine.
A way to do this could be to use the remote debugging functionalities provided
by LLDB via the GDB-remote protocol. Remote debugging can indeed be useful not
only to connect a debugger to a process running on a remote machine, but also to
connect the debugger to a managed VM or script engine that runs locally,
provided that the engine implements a GDB-remote stub that offers the ability to
access the engine runtime internal state.
To make this work, the GDB-remote protocol would need to be extended with a few
Wasm-specific custom query commands, used to access aspects of the Wasm engine
state (like the Wasm memory, Wasm local and global variables, and so on).
Furthermore, the DWARF format would need to be enriched with a few Wasm-specific
extensions, here detailed: https://yurydelendik.github.io/webassembly-dwarf.
This CL introduce classes **ObjectFileWasm**, a file plugin to represent a Wasm
module loaded in a debuggee process. It knows how to parse Wasm modules and
store the Code section and the DWARF-specific sections.
Reviewers: jasonmolenda, clayborg, labath
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D71575
These are the last sections not managed by the DWARFContext object. I
also introduce separate SectionType enums for dwo section variants, as
this is necessary for proper handling of single-file split dwarf.
This fixes a failing testcase on Fedora 30 x86_64 (regression Fedora 29->30):
PASS:
./bin/lldb ./lldb-test-build.noindex/functionalities/unwind/noreturn/TestNoreturnUnwind.test_dwarf/a.out -o 'settings set symbols.enable-external-lookup false' -o r -o bt -o quit
* frame #0: 0x00007ffff7aa6e75 libc.so.6`__GI_raise + 325
frame #1: 0x00007ffff7a91895 libc.so.6`__GI_abort + 295
frame #2: 0x0000000000401140 a.out`func_c at main.c:12:2
frame #3: 0x000000000040113a a.out`func_b at main.c:18:2
frame #4: 0x0000000000401134 a.out`func_a at main.c:26:2
frame #5: 0x000000000040112e a.out`main(argc=<unavailable>, argv=<unavailable>) at main.c:32:2
frame #6: 0x00007ffff7a92f33 libc.so.6`__libc_start_main + 243
frame #7: 0x000000000040106e a.out`_start + 46
vs.
FAIL - unrecognized abort() function:
./bin/lldb ./lldb-test-build.noindex/functionalities/unwind/noreturn/TestNoreturnUnwind.test_dwarf/a.out -o 'settings set symbols.enable-external-lookup false' -o r -o bt -o quit
* frame #0: 0x00007ffff7aa6e75 libc.so.6`.annobin_raise.c + 325
frame #1: 0x00007ffff7a91895 libc.so.6`.annobin_loadmsgcat.c_end.unlikely + 295
frame #2: 0x0000000000401140 a.out`func_c at main.c:12:2
frame #3: 0x000000000040113a a.out`func_b at main.c:18:2
frame #4: 0x0000000000401134 a.out`func_a at main.c:26:2
frame #5: 0x000000000040112e a.out`main(argc=<unavailable>, argv=<unavailable>) at main.c:32:2
frame #6: 0x00007ffff7a92f33 libc.so.6`.annobin_libc_start.c + 243
frame #7: 0x000000000040106e a.out`.annobin_init.c.hot + 46
The extra ELF symbols are there due to Annobin (I did not investigate why this
problem happened specifically since F-30 and not since F-28).
It is due to:
Symbol table '.dynsym' contains 2361 entries:
Valu e Size Type Bind Vis Name
0000000000022769 5 FUNC LOCAL DEFAULT _nl_load_domain.cold
000000000002276e 0 NOTYPE LOCAL HIDDEN .annobin_abort.c.unlikely
...
000000000002276e 0 NOTYPE LOCAL HIDDEN .annobin_loadmsgcat.c_end.unlikely
...
000000000002276e 0 NOTYPE LOCAL HIDDEN .annobin_textdomain.c_end.unlikely
000000000002276e 548 FUNC GLOBAL DEFAULT abort
000000000002276e 548 FUNC GLOBAL DEFAULT abort@@GLIBC_2.2.5
000000000002276e 548 FUNC LOCAL DEFAULT __GI_abort
0000000000022992 0 NOTYPE LOCAL HIDDEN .annobin_abort.c_end.unlikely
GDB has some more complicated preferences between overlapping and/or sharing
address symbols, I have made here so far the most simple fix for this case.
Differential revision: https://reviews.llvm.org/D63540
This error message didn't specify which file was malformed, so
there's some hunting-around required if it comes up. We have the
filename; include it in the error message.
Remove the hack that populates the cpsr register in the gpr struct by
writing past the end of the array. This was tripping up ASan.
Patch by: Reva Cuthbertson
If not set, the address byte size was implied to be the one of the
host process.
This allows reverting the functional change from 31087b2ae9154, since
now PECOFF does the same as ELF and MachO wrt setting both byte order
and address size on m_data within ParseHeader.
Differential Revision: https://reviews.llvm.org/D71108
COFF section names can either be stored truncated to 8 chars, in the
section header, or as a longer section name, stored separately in the
string table.
libunwind locates the .eh_frame section by runtime introspection,
which only works for section names stored in the section header (as
the string table isn't mapped at runtime). To support this behaviour,
lld always truncates the section names for sections that will be
mapped, like .eh_frame.
Differential Revision: https://reviews.llvm.org/D70745
llvm::object::createBinary returns an Expected<>, which requires
not only checking the object for success, but also requires consuming
the Error, if one was set.
Use LLDB_LOG_ERROR for this case, and change an existing similar log
statement to use it as well, to make sure the Error is consumed even
if the log channel is disabled.
Differential Revision: https://reviews.llvm.org/D69646
Summary:
This enables us to reason about whether a given address can be
executable, for instance during unwinding.
Reviewers: amccarth, mstorsjo
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D69102
The virtual container/header section caused the section list to be
offset by one, but by using FindSectionByID, the layout of the
section list shouldn't matter.
Differential Revision: https://reviews.llvm.org/D69366
In an attempt to ensure that every part of the module's memory image is
accounted for, D56537 created a special "container section" spanning the
entire image. While that seemed reasonable at the time (and it still
mostly does), it did create a problem of what to put as the "file size"
of the section, because the image is not continuous on disk, as we
generally assume (which is why I put zero there). Additionally, this
arrangement makes it unclear what kind of permissions should be assigned
to that section (which is what my next patch does).
To get around these, this patch partially reverts D56537, and goes back
to top-level sections. Instead, what I do is create a new "section" for
the object file header, which is also being loaded into memory, though
its not considered to be a section in the strictest sense. This makes it
possible to correctly assign file size section, and we can later assign
permissions to it as well.
Reviewers: amccarth, mstorsjo
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D69100
This patch removes the size_t return value and the append parameter
from the remainder of the Find.* functions in LLDB's internal API. As
in the previous patches, this is motivated by the fact that these
parameters aren't really used, and in the case of the append parameter
were frequently implemented incorrectly.
Differential Revision: https://reviews.llvm.org/D69119
llvm-svn: 375160
This matches all other architectures listed in the same file.
This fixes debugging aarch64 executables with lldb-server, which
otherwise fails, with log messages like these:
Target::SetArchitecture changing architecture to aarch64 (aarch64-pc-windows-msvc)
Target::SetArchitecture Trying to select executable file architecture aarch64 (aarch64-pc-windows-msvc)
ArchSpec::SetArchitecture sets the vendor to llvm::Triple::PC
for any coff/win32 combination, and if this doesn't match the triple
set by the PECOFF module, things doesn't seem to work with when
using lldb-server.
Differential Revision: https://reviews.llvm.org/D68939
llvm-svn: 374867
This patch adds an implementation of unwinding using PE EH info. It allows to
get almost ideal call stacks on 64-bit Windows systems (except some epilogue
cases, but I believe that they can be fixed with unwind plan disassembly
augmentation in the future).
To achieve the goal the CallFrameInfo abstraction was made. It is based on the
DWARFCallFrameInfo class interface with a few changes to make it less
DWARF-specific.
To implement the new interface for PECOFF object files the class PECallFrameInfo
was written. It uses the next helper classes:
- UnwindCodesIterator helps to iterate through UnwindCode structures (and
processes chained infos transparently);
- EHProgramBuilder with the use of UnwindCodesIterator constructs EHProgram;
- EHProgram is, by fact, a vector of EHInstructions. It creates an abstraction
over the low-level unwind codes and simplifies work with them. It contains
only the information that is relevant to unwinding in the unified form. Also
the required unwind codes are read from the object file only once with it;
- EHProgramRange allows to take a range of EHProgram and to build an unwind row
for it.
So, PECallFrameInfo builds the EHProgram with EHProgramBuilder, takes the ranges
corresponding to every offset in prologue and builds the rows of the resulted
unwind plan. The resulted plan covers the whole range of the function except the
epilogue.
Reviewers: jasonmolenda, asmith, amccarth, clayborg, JDevlieghere, stella.stamenova, labath, espindola
Reviewed By: jasonmolenda
Subscribers: leonid.mashinskiy, emaste, mgorny, aprantl, arichardson, MaskRay, lldb-commits, llvm-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D67347
llvm-svn: 374528
Testing whether a name is mangled or not is extremely cheap and can be
done by looking at the first two characters. Mangled knows how to do
it. On the flip side, many call sites that currently pass in an
is_mangled determination do not know how to correctly do it (for
example, they leave out Swift mangling prefixes).
This patch removes this entry point and just forced Mangled to
determine the mangledness of a string itself.
Differential Revision: https://reviews.llvm.org/D68674
llvm-svn: 374180
David added the JamCRC implementation in r246590. More recently, Eugene
added a CRC-32 implementation in r357901, which falls back to zlib's
crc32 function if present.
These checksums are essentially the same, so having multiple
implementations seems unnecessary. This replaces the CRC-32
implementation with the simpler one from JamCRC, and implements the
JamCRC interface in terms of CRC-32 since this means it can use zlib's
implementation when available, saving a few bytes and potentially making
it faster.
JamCRC took an ArrayRef<char> argument, and CRC-32 took a StringRef.
This patch changes it to ArrayRef<uint8_t> which I think is the best
choice, and simplifies a few of the callers nicely.
Differential revision: https://reviews.llvm.org/D68570
llvm-svn: 374148
Summary:
This is a redo of D68069 because I reverted it due to some concerns that were now addressed along with the new comments that @labath added.
I found a case where the main android binary (app_process32) had thumb code at its entry point but no entry in the symbol table indicating this. This made lldb set a 4 byte breakpoint at that address (we default to arm code) instead of a 2 byte one (like we should for thumb).
The big deal with this is that the expression evaluator uses the entry point as a way to know when a JITed expression has finished executing by putting a breakpoint there. Because of this, evaluating expressions on certain android devices (Google Pixel something) made the process crash.
This was fixed by checking this specific situation when we parse the symbol table and add an artificial symbol for this 2 byte range and indicating that it's arm thumb.
I created 2 unit tests for this, one to check that now we know that the entry point is arm thumb, and the other to make sure we didn't change the behaviour for arm code.
I also run the following on the command line with the `app_process32` where I found the issue:
**Before:**
```
(lldb) dis -s 0x1640 -e 0x1644
app_process32[0x1640]: .long 0xf0004668 ; unknown opcode
```
**After:**
```
(lldb) dis -s 0x1640 -e 0x1644
app_process32`:
app_process32[0x1640] <+0>: mov r0, sp
app_process32[0x1642]: andeq r0, r0, r0
```
Reviewers: clayborg, labath, wallace, espindola
Reviewed By: labath
Subscribers: labath, lldb-commits, MaskRay, kristof.beyls, arichardson, emaste, srhines
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D68533
llvm-svn: 374132
This makes parsing the symbol table of clang marginally faster. (Hashtable versus tree).
Differential Revision: https://reviews.llvm.org/D68605
llvm-svn: 374084
The symtab parser in ObjectFileMachO has logic to coalesce debug (STAB)
and non-debug symbols, based on the address and the symbol name for
static (STSYM) and global symbols (GSYM) respectively. It makes the
assumption that the debug variant is always encountered first. Rather
than creating a second entry in the symbol table for the non-debug
symbol, the latter gets merged into the existing debug symbol.
This breaks when the linker emits the non-debug symbol first. We'd end
up with two entries in the symbol table, each containing part of the
information LLDB relies on. Indeed, commenting out the merging logic
breaks the test suite spectacularly.
This patch solves that problem by always parsing the debug symbols
first. This guarantees that the assumption for merging holds.
I'm not particularly happy with adding a lambda, but after numerous
attempts this is the best solution I could come up with. The symtab
parsing logic is pretty complex in that it touches a lot of things. I've
experienced first hand that it's very easy to break things. I believe
this approach strikes a balance between fixing the issue while limiting
the risk of regressions.
Differential revision: https://reviews.llvm.org/D68536
llvm-svn: 373994
Summary:
If the .symtab section is stripped from the binary it might be that
there's a .gnu_debugdata section which contains a smaller .symtab in
order to provide enough information to create a backtrace with function
names or to set and hit a breakpoint on a function name.
This change looks for a .gnu_debugdata section in the ELF object file.
The .gnu_debugdata section contains a xz-compressed ELF file with a
.symtab section inside. Symbols from that compressed .symtab section
are merged with the main object file's .dynsym symbols (if any).
In addition we always load the .dynsym even if there's a .symtab
section.
For example, the Fedora and RHEL operating systems strip their binaries
but keep a .gnu_debugdata section. While gdb already can read this
section, LLDB until this patch couldn't. To test this patch on a
Fedora or RHEL operating system, try to set a breakpoint on the "help"
symbol in the "zip" binary. Before this patch, only GDB can set this
breakpoint; now LLDB also can do so without installing extra debug
symbols:
lldb /usr/bin/zip -b -o "b help" -o "r" -o "bt" -- -h
The above line runs LLDB in batch mode and on the "/usr/bin/zip -h"
target:
(lldb) target create "/usr/bin/zip"
Current executable set to '/usr/bin/zip' (x86_64).
(lldb) settings set -- target.run-args "-h"
Before the program starts, we set a breakpoint on the "help" symbol:
(lldb) b help
Breakpoint 1: where = zip`help, address = 0x00000000004093b0
Once the program is run and has hit the breakpoint we ask for a
backtrace:
(lldb) r
Process 10073 stopped
* thread #1, name = 'zip', stop reason = breakpoint 1.1
frame #0: 0x00000000004093b0 zip`help
zip`help:
-> 0x4093b0 <+0>: pushq %r12
0x4093b2 <+2>: movq 0x2af5f(%rip), %rsi ; + 4056
0x4093b9 <+9>: movl $0x1, %edi
0x4093be <+14>: xorl %eax, %eax
Process 10073 launched: '/usr/bin/zip' (x86_64)
(lldb) bt
* thread #1, name = 'zip', stop reason = breakpoint 1.1
* frame #0: 0x00000000004093b0 zip`help
frame #1: 0x0000000000403970 zip`main + 3248
frame #2: 0x00007ffff7d8bf33 libc.so.6`__libc_start_main + 243
frame #3: 0x0000000000408cee zip`_start + 46
In order to support the .gnu_debugdata section, one has to have LZMA
development headers installed. The CMake section, that controls this
part looks for the LZMA headers and enables .gnu_debugdata support by
default if they are found; otherwise or if explicitly requested, the
minidebuginfo support is disabled.
GDB supports the "mini debuginfo" section .gnu_debugdata since v7.6
(2013).
Reviewers: espindola, labath, jankratochvil, alexshap
Reviewed By: labath
Subscribers: rnkovacs, wuzish, shafik, emaste, mgorny, arichardson, hiraditya, MaskRay, lldb-commits
Tags: #lldb, #llvm
Differential Revision: https://reviews.llvm.org/D66791
llvm-svn: 373891
This file really suffered from the Great Reformat. I'm adding a few
early returns to give the deeply nested code some more breathing room.
llvm-svn: 373778
Backing out because SymbolFile/Breakpad/symtab.test is failing and it seems to be a legit issue. Will investigate.
This reverts commit 72153f95ee4c1b52d2f4f483f0ea4f650ec863be.
llvm-svn: 373687
Summary:
I found a case where the main android binary (app_process32) had thumb code at its entry point but no entry in the symbol table indicating this. This made lldb set a 4 byte breakpoint at that address (we default to arm code) instead of a 2 byte one (like we should for thumb).
The big deal with this is that the expression evaluator uses the entry point as a way to know when a JITed expression has finished executing by putting a breakpoint there. Because of this, evaluating expressions on certain android devices (Google Pixel something) made the process crash.
This was fixed by checking this specific situation when we parse the symbol table and add an artificial symbol for this 2 byte range and indicating that it's arm thumb.
I created 2 unit tests for this, one to check that now we know that the entry point is arm thumb, and the other to make sure we didn't change the behaviour for arm code.
I also run the following on the command line with the `app_process32` where I found the issue:
**Before:**
```
(lldb) dis -s 0x1640 -e 0x1644
app_process32[0x1640]: .long 0xf0004668 ; unknown opcode
```
**After:**
```
(lldb) dis -s 0x1640 -e 0x1644
app_process32`:
app_process32[0x1640] <+0>: mov r0, sp
app_process32[0x1642]: andeq r0, r0, r0
```
Reviewers: clayborg, labath, wallace, espindola
Subscribers: srhines, emaste, arichardson, kristof.beyls, MaskRay, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D68069
llvm-svn: 373680
Summary:
This patch converts FileSystem::Open from this prototype:
Status
Open(File &File, const FileSpec &file_spec, ...);
to this one:
llvm::Expected<std::unique_ptr<File>>
Open(const FileSpec &file_spec, ...);
This is beneficial on its own, as llvm::Expected is a more modern
and recommended error type than Status. It is also a necessary step
towards https://reviews.llvm.org/D67891, and further developments
for lldb_private::File.
Reviewers: JDevlieghere, jasonmolenda, labath
Reviewed By: labath
Subscribers: mgorny, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D67996
llvm-svn: 373003
Add a test case for the change from SVN r372657, and for the
preexisting ARM identification.
Add a missing ArchDefinitionEntry for PECOFF/arm64, and tweak
the ArmNt case to set the architecture to armv7 (ArmNt never ran
on anything lower than that). (This avoids a case where
ArchSpec::MergeFrom would override the arch from arm to armv7 and
ArchSpec::CoreUpdated would reset the OS to unknown at the same time.)
Differential Revision: https://reviews.llvm.org/D67951
llvm-svn: 372741
The PECOFF object file plugin uses the dbghelp API, but doesn't
specify that it has to be linked in anywhere.
Current MSVC based builds have probably succeeded, as other parts
in LLDB have had a "#pragma comment(lib, "dbghelp.lib")", but there's
currently no such pragma in the PECOFF plugin.
The "#pragma comment(lib, ...)" approach doesn't work in MinGW mode
(unless the compiler is given the -fms-extensions option, and even
then, it's only supported by clang/lld, not by GCC/binutils), thus
add it to be linked via CMake. (The other parts of LLDB that use
dbghelp are within _MSC_VER ifdefs.)
Differential Revision: https://reviews.llvm.org/D67885
llvm-svn: 372587
Summary:
This change ensures that the .dynsym section will be parsed even when there's already is a .symtab.
It is motivated because of minidebuginfo (https://sourceware.org/gdb/current/onlinedocs/gdb/MiniDebugInfo.html#MiniDebugInfo).
There it says:
Keep all the function symbols not already in the dynamic symbol table.
That means the .symtab embedded inside the .gnu_debugdata does NOT contain the symbols from .dynsym. But in order to put a breakpoint on all symbols we need to load both. I hope this makes sense.
My other patch D66791 implements support for minidebuginfo, that's why I need this change.
Reviewers: labath, espindola, alexshap
Subscribers: JDevlieghere, emaste, arichardson, MaskRay, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D67390
llvm-svn: 371599
