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
The function had the same name as one of the member function, so
it was just copied to all classes so that the lookup works. We
could also give the function a more better and unique name
(because it's actually printing the register value and writing
to the stream, not writing to the register).
Also removes the unused return value.
llvm-svn: 370854
Summary: The fields that aren't useful for us right now are simply ignored.
Reviewers: amccarth, markmentovai
Subscribers: rnk, lldb-commits
Differential Revision: https://reviews.llvm.org/D66633
llvm-svn: 369892
On macOS one Mach-O slice can contain multiple load commands: One load
command for being loaded into a macOS process and one load command for
being loaded into a macCatalyst process. This patch adds support for
the new load command and makes sure ObjectFileMachO returns the
Architecture that matches the Module.
Differential Revision: https://reviews.llvm.org/D66626
llvm-svn: 369814
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.
Differential revision: https://reviews.llvm.org/D66259
llvm-svn: 368933
Summary:
In an attempt to make file-address-based lookups more predictable, in D55998
we started ignoring sections which would result in file address
overlaps. It turns out this was too aggressive because thread-local
sections typically will have file addresses which apear to overlap
regular data/code. This does not cause a problem at runtime because
thread-local sections are loaded into memory using special logic, but it
can cause problems for lldb when trying to lookup objects by their file
address.
This patch changes ObjectFileELF to permit thread-local sections to
overlap regular ones by essentially giving them a separate address
space. It also makes them more symmetrical to regular sections by
creating container sections from PT_TLS segments.
Simultaneously, the patch changes the regular file address lookup logic
to ignore sections with the thread-specific bit set. I believe this is
what the users looking up file addresses would typically expect, as
looking up thread-local data generally requires more complex logic (e.g.
DWARF has a special opcode for that).
Reviewers: clayborg, jingham, MaskRay
Subscribers: emaste, aprantl, arichardson, lldb-commits
Differential Revision: https://reviews.llvm.org/D65282
llvm-svn: 368010
Summary:
The contents of the gnu_debuglink section were passed through the
GetDebugSymbolFilePaths interface, which was more generic than needed.
As the only class implementing this function is ObjectFileELF, we can
modify the function to return just a single FileSpec (instead of a
list). Also, since the SymbolVendorELF already assumes ELF object files,
we don't have to make this method available on the generic ObjectFile
interface -- instead we can put it on ObjectFileELF directly.
This change also makes is so that if the Module has an explicit symbol
file spec set, we disregard the value the value of the debug link
(instead of doing a secondary lookup using that). I think it makes sense
to honor the users wishes if he had explicitly set the symbol file spec,
and this seems to be consistent with what SymbolVendorMacOSX is doing
(SymbolVendorMacOSX.cpp:125).
The main reason for making these changes is to make the treatment of
build-ids and debug links simpler in the follow-up patch.
Reviewers: clayborg, jankratochvil, mgorny, espindola
Subscribers: emaste, arichardson, MaskRay, lldb-commits
Differential Revision: https://reviews.llvm.org/D65560
llvm-svn: 367824
Summary:
On the heels of D62934, this patch uses the same approach to introduce
llvm RTTI support to the ObjectFile hierarchy. It also replaces the
existing uses of GetPluginName doing run-time type checks with
llvm::dyn_cast and friends.
This formally introduces new dependencies from some other plugins to
ObjectFile plugins. However, I believe this is fine because:
- these dependencies were already kind of there, and the only reason
we could get away with not modeling them explicitly was because the
code was relying on magically knowing what will GetPluginName() return
for a particular kind of object files.
- the dependencies themselves are logical (it makes sense for
SymbolVendorELF to depend on ObjectFileELF), or at least don't
actively get in the way (the JitLoaderGDB->MachO thing).
- they don't introduce any new dependency loops as ObjectFile plugins
don't depend on any other plugins
Reviewers: xiaobai, JDevlieghere, espindola
Subscribers: emaste, mgorny, arichardson, MaskRay, lldb-commits
Differential Revision: https://reviews.llvm.org/D65450
llvm-svn: 367413
This time, the warning pointed to an actual problem, because the
coff_opt_header structure contained a std::vector. I guess this happened
to work because the all-zero state was a valid representation of an
empty vector, but its not a good idea to rely on that.
I remove the memset, and have the structure clear its members in the
constructor instead.
llvm-svn: 367299
This patch replaces explicit calls to log::Printf with the new LLDB_LOGF
macro. The macro is similar to LLDB_LOG but supports printf-style format
strings, instead of formatv-style format strings.
So instead of writing:
if (log)
log->Printf("%s\n", str);
You'd write:
LLDB_LOG(log, "%s\n", str);
This change was done mechanically with the command below. I replaced the
spurious if-checks with vim, since I know how to do multi-line
replacements with it.
find . -type f -name '*.cpp' -exec \
sed -i '' -E 's/log->Printf\(/LLDB_LOGF\(log, /g' "{}" +
Differential revision: https://reviews.llvm.org/D65128
llvm-svn: 366936
Just delete the memset as the ELFHeader constructor already
zero-initializes the object. Also clean up the ObjectFileELF
constructors/desctructors while I'm in there.
llvm-svn: 366692
The new DriverKit user-land kernel drivers in macOS 10.15 / Catalina
do not have a main() function or an LC_MAIN load command. lldb uses
the address of main() as the return address for inferior function
calls; it puts a breakpoint on main, runs the inferior function call,
and when the main() breakpoint is hit, lldb knows unambiguously that
the inferior function call ran to completion - no other function calls
main.
This change hoists the logic for finding the "entry address" from
ThreadPlanCallFunction to Target. It changes the logic to first
try to get the entry address from the main executable module,
but if that module does not have one, it will iterate through all
modules looking for an entry address.
The patch also adds code to ObjectFileMachO to use dyld's
_dyld_start function as an entry address.
<rdar://problem/52343958>
Differential Revision: https://reviews.llvm.org/D64897
llvm-svn: 366493
Instead of having to write FileSpecList::Append(FileSpec(args)) you can
now call FileSpecList::EmplaceBack(args), similar to
std::vector<>::emplace_back.
llvm-svn: 366489
With this style, a compressed section is indicated by a "z" in the section
name, instead of a section header flag. This patch consists of two small tweaks:
- use an llvm Decompressor method in order to properly detect compressed sections
- make sure we recognise .zdebug_info (and friends) when classifying section types.
llvm-svn: 365654
Summary: This patch modernizes the GetSDKVersion API and hopefully prevents problems such as the ones discovered in D61218.
Reviewers: aprantl, jasonmolenda, clayborg
Reviewed By: aprantl, clayborg
Subscribers: clayborg, labath, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D61233
llvm-svn: 365090
operator new doesn't return a null pointer, even if one turns off
exceptions (it calls std::terminate instead). Therefore, all of this is
dead code.
llvm-svn: 364744
Summary:
NFC = [[ https://llvm.org/docs/Lexicon.html#nfc | Non functional change ]]
This commit is the result of modernizing the LLDB codebase by using
`nullptr` instread of `0` or `NULL`. See
https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-nullptr.html
for more information.
This is the command I ran and I to fix and format the code base:
```
run-clang-tidy.py \
-header-filter='.*' \
-checks='-*,modernize-use-nullptr' \
-fix ~/dev/llvm-project/lldb/.* \
-format \
-style LLVM \
-p ~/llvm-builds/debug-ninja-gcc
```
NOTE: There were also changes to `llvm/utils/unittest` but I did not
include them because I felt that maybe this library shall be updated in
isolation somehow.
NOTE: I know this is a rather large commit but it is a nobrainer in most
parts.
Reviewers: martong, espindola, shafik, #lldb, JDevlieghere
Reviewed By: JDevlieghere
Subscribers: arsenm, jvesely, nhaehnle, hiraditya, JDevlieghere, teemperor, rnkovacs, emaste, kubamracek, nemanjai, ki.stfu, javed.absar, arichardson, kbarton, jrtc27, MaskRay, atanasyan, dexonsmith, arphaman, jfb, jsji, jdoerfert, lldb-commits, llvm-commits
Tags: #lldb, #llvm
Differential Revision: https://reviews.llvm.org/D61847
llvm-svn: 361484
Summary:
First part of a fix for JITed code debugging. This has been a regression from 5.0 to 6.0 and it's is still reproducible on current master: https://bugs.llvm.org/show_bug.cgi?id=36209
The address of the breakpoint site is corrupt: the 0x4 value we end up with, looks like an offset on a zero base address. When we parse the ELF section headers from the JIT descriptor, the load address for the text section we find in `header.sh_addr` is correct.
The bug manifests in `VMAddressProvider::GetVMRange(const ELFSectionHeader &)` (follow it from `ObjectFileELF::CreateSections()`). Here we think the object type was `eTypeObjectFile` and unleash some extra logic [1] which essentially overwrites the address with a zero value.
The object type is deduced from the ELF header's `e_type` in `ObjectFileELF::CalculateType()`. It never returns `eTypeJIT`, because the ELF header has no representation for it [2]. Instead the in-memory ELF object states `ET_REL`, which leads to `eTypeObjectFile`. This is what we get from `lli` at least since 3.x. (Might it be better to write `ET_EXEC` on the JIT side instead? In fact, relocations were already applied at this point, so "Relocatable" is not quite exact.)
So, this patch proposes to set `eTypeJIT` explicitly whenever we read from a JIT descriptor. In `ObjectFileELF::CreateSections()` we can then call `GetType()`, which returns the explicit value or otherwise falls back to `CalculateType()`.
LLDB then sets the breakpoint successfully. Next step: debug info.
```
Process 1056 stopped
* thread #1, name = 'lli', stop reason = breakpoint 1.2
frame #0: 0x00007ffff7ff7000 JIT(0x3ba2030)`jitbp()
JIT(0x3ba2030)`jitbp:
-> 0x7ffff7ff7000 <+0>: pushq %rbp
0x7ffff7ff7001 <+1>: movq %rsp, %rbp
0x7ffff7ff7004 <+4>: movabsq $0x7ffff7ff6000, %rdi ; imm = 0x7FFFF7FF6000
0x7ffff7ff700e <+14>: movabsq $0x7ffff6697e80, %rcx ; imm = 0x7FFFF6697E80
```
[1] It was first introduced with https://reviews.llvm.org/D38142#change-lF6csxV8HdlL, which has also been the original breaking change. The code has changed a lot since then.
[2] ELF object types: https://github.com/llvm/llvm-project/blob/2d2277f5/llvm/include/llvm/BinaryFormat/ELF.h#L110
Reviewers: labath, JDevlieghere, bkoropoff, clayborg, espindola, alexshap, stella.stamenova
Reviewed By: labath, clayborg
Subscribers: probinson, emaste, aprantl, arichardson, MaskRay, AlexDenisov, yurydelendik, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D61611
llvm-svn: 360354
Summary:
According to [C128] "Virtual functions should specify exactly one
of `virtual`, `override`, or `final`", I've added override where a
virtual function is overriden but the explicit `override` keyword
was missing. Whenever both `virtual` and `override` were specified,
I removed `virtual`. As C.128 puts it:
> [...] writing more than one of these three is both redundant and
> a potential source of errors.
I anticipate a discussion about whether or not to add `override` to
destructors but I went for it because of an example in [ISOCPP1000].
Let me repeat the comment for you here:
Consider this code:
```
struct Base {
virtual ~Base(){}
};
struct SubClass : Base {
~SubClass() {
std::cout << "It works!\n";
}
};
int main() {
std::unique_ptr<Base> ptr = std::make_unique<SubClass>();
}
```
If for some odd reason somebody removes the `virtual` keyword from the
`Base` struct, the code will no longer print `It works!`. So adding
`override` to destructors actively protects us from accidentally
breaking our code at runtime.
[C128]: https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c128-virtual-functions-should-specify-exactly-one-of-virtual-override-or-final
[ISOCPP1000]: https://github.com/isocpp/CppCoreGuidelines/issues/1000#issuecomment-476951555
Reviewers: teemperor, JDevlieghere, davide, shafik
Reviewed By: teemperor
Subscribers: kwk, arphaman, kadircet, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D61440
llvm-svn: 359868
Summary:
When we want to compare a ConstString against a string literal (or any other non-ConstString),
we currently have to explicitly turn the other string into a ConstString. This makes sense as
comparing ConstStrings against each other is only a fast pointer comparison.
However, currently we (rather incorrectly) use in several places in LLDB temporary ConstStrings when
we just want to compare a given ConstString against a hardcoded value, for example like this:
```
if (extension != ConstString(".oat") && extension != ConstString(".odex"))
```
Obviously this kind of defeats the point of ConstStrings. In the comparison above we would
construct two temporary ConstStrings every time we hit the given code. Constructing a
ConstString is relatively expensive: we need to go to the StringPool, take a read and possibly
an exclusive write-lock and then look up our temporary string in the string map of the pool.
So we do a lot of heavy work for essentially just comparing a <6 characters in two strings.
I initially wanted to just fix these issues by turning the temporary ConstString in static variables/
members, but that made the code much less readable. Instead I propose to add a new overload
for the ConstString comparison operator that takes a StringRef. This comparison operator directly
compares the ConstString content against the given StringRef without turning the StringRef into
a ConstString.
This means that the example above can look like this now:
```
if (extension != ".oat" && extension != ".odex")
```
It also no longer has to unlock/lock two locks and call multiple functions in other TUs for constructing
the temporary ConstString instances. Instead this should end up just being a direct string comparison
of the two given strings on most compilers.
This patch also directly updates all uses of temporary and short ConstStrings in LLDB to use this new
comparison operator. It also adds a some unit tests for the new and old comparison operator.
Reviewers: #lldb, JDevlieghere, espindola, amccarth
Reviewed By: JDevlieghere, amccarth
Subscribers: amccarth, clayborg, JDevlieghere, emaste, arichardson, MaskRay, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D60667
llvm-svn: 359281
