Update setup and build instructions. #2
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Fix a few typos in Setup-and-Build.md. Add a missing hyperlink for how to update to newer versions of the LLVM/clang sources.
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dtarditi
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Jun 20, 2017
…and. Rank such guides below explicit ones, and ensure that references to the class's template parameters are not treated as forwarding references. We make a few tweaks to the wording in the current standard: 1) The constructor parameter list is copied faithfully to the deduction guide, without losing default arguments or a varargs ellipsis (which the standard wording loses by omission). 2) If the class template declares no constructors, we add a T() -> T<...> guide (which will only ever work if T has default arguments for all non-pack template parameters). 3) If the class template declares nothing that looks like a copy or move constructor, we add a T(T<...>) -> T<...> guide. #2 and #3 follow from the "pretend we had a class type with these constructors" philosophy for deduction guides. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@295007 91177308-0d34-0410-b5e6-96231b3b80d8
dtarditi
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Jan 26, 2019
… CompoundAssign operators Summary: As reported by @regehr (thanks!) on twitter (https://twitter.com/johnregehr/status/1057681496255815686), we (me) has completely forgot about the binary assignment operator. In AST, it isn't represented as separate `ImplicitCastExpr`'s, but as a single `CompoundAssignOperator`, that does all the casts internally. Which means, out of these two, only the first one is diagnosed: ``` auto foo() { unsigned char c = 255; c = c + 1; return c; } auto bar() { unsigned char c = 255; c += 1; return c; } ``` https://godbolt.org/z/JNyVc4 This patch does handle the `CompoundAssignOperator`: ``` int main() { unsigned char c = 255; c += 1; return c; } ``` ``` $ ./bin/clang -g -fsanitize=integer /tmp/test.c && ./a.out /tmp/test.c:3:5: runtime error: implicit conversion from type 'int' of value 256 (32-bit, signed) to type 'unsigned char' changed the value to 0 (8-bit, unsigned) #0 0x2392b8 in main /tmp/test.c:3:5 #1 0x7fec4a612b16 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x22b16) #2 0x214029 in _start (/build/llvm-build-GCC-release/a.out+0x214029) ``` However, the pre/post increment/decrement is still not handled. Reviewers: rsmith, regehr, vsk, rjmccall, #sanitizers Reviewed By: rjmccall Subscribers: mclow.lists, cfe-commits, regehr Tags: #clang, #sanitizers Differential Revision: https://reviews.llvm.org/D53949 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@347258 91177308-0d34-0410-b5e6-96231b3b80d8
abeln
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Aug 7, 2019
Error #1: we were keeping track of visited nodes during the search with a tuple (RecordDecl, TypeVariableType, Expanding). This doesn't work because multiple records share the same TypeVariableType. Instead, use (RecordDecl, TypeVariableIndex, Expanding), which is unique. Error #2: we were missing the recursive case when looking for edges in RecordTypes.
mgrang
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Oct 30, 2019
Summary: Major fixes after D54476 (use Diff1 as base for comparison to see only recent changes): * In standalone builds target directory for debugserver must be LLDB's bin, not LLVM's bin * Default identity for code signing must not force-override LLVM_CODESIGNING_IDENTITY globally We have a lot of cases, make them explicit: * ID used for code signing (debugserver and in tests): ** `LLDB_CODESIGN_IDENTITY` if set explicitly, or otherwise ** `LLVM_CODESIGNING_IDENTITY` if set explicitly, or otherwise ** `lldb_codesign` as the default * On Darwin we have a debugserver target that: * On other systems, the debugserver target is not defined, which is equivalent to **[3A]** Common configurations on Darwin: * **[1A]** `cmake -GNinja ../llvm` builds debugserver from source and signs with `lldb_codesign`, no code signing for other binaries (prints status: //lldb debugserver: /path/to/bin/debugserver//) * **[1A]** `cmake -GNinja -DLLVM_CODESIGNING_IDENTITY=- -DLLDB_CODESIGN_IDENTITY=lldb_codesign ../llvm` builds debugserver from source and signs with `lldb_codesign`, ad-hoc code signing for other binaries (prints status: //lldb debugserver: /path/to/bin/debugserver//) * **[2A]** `cmake -GNinja -DLLVM_CODESIGNING_IDENTITY=- -DLLDB_USE_SYSTEM_DEBUGSERVER=ON ../llvm` copies debugserver from system, ad-hoc code signing for other binaries (prints status: //Copy system debugserver from: /path/to/system/debugserver//) * **[2B]** `cmake -GNinja -DLLVM_CODESIGNING_IDENTITY=- ../llvm` same, but prints additional warning: //Cannot code sign debugserver with identity '-'. Will fall back to system's debugserver. Pass -DLLDB_CODESIGN_IDENTITY=lldb_codesign to override the LLVM value for debugserver.// * **[3A]** `cmake -GNinja -DLLVM_CODESIGNING_IDENTITY=- -DLLDB_NO_DEBUGSERVER=ON ../llvm` debugserver not available (prints status: //lldb debugserver will not be available)// Reviewers: JDevlieghere, beanz, davide, vsk, aprantl, labath Reviewed By: JDevlieghere, labath Subscribers: mgorny, #lldb, lldb-commits Differential Revision: https://reviews.llvm.org/D55013 llvm-svn: 350388
mgrang
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Feb 18, 2020
Introduction ============ This patch added intial support for bpf program compile once and run everywhere (CO-RE). The main motivation is for bpf program which depends on kernel headers which may vary between different kernel versions. The initial discussion can be found at https://lwn.net/Articles/773198/. Currently, bpf program accesses kernel internal data structure through bpf_probe_read() helper. The idea is to capture the kernel data structure to be accessed through bpf_probe_read() and relocate them on different kernel versions. On each host, right before bpf program load, the bpfloader will look at the types of the native linux through vmlinux BTF, calculates proper access offset and patch the instruction. To accommodate this, three intrinsic functions preserve_{array,union,struct}_access_index are introduced which in clang will preserve the base pointer, struct/union/array access_index and struct/union debuginfo type information. Later, bpf IR pass can reconstruct the whole gep access chains without looking at gep itself. This patch did the following: . An IR pass is added to convert preserve_*_access_index to global variable who name encodes the getelementptr access pattern. The global variable has metadata attached to describe the corresponding struct/union debuginfo type. . An SimplifyPatchable MachineInstruction pass is added to remove unnecessary loads. . The BTF output pass is enhanced to generate relocation records located in .BTF.ext section. Typical CO-RE also needs support of global variables which can be assigned to different values to different hosts. For example, kernel version can be used to guard different versions of codes. This patch added the support for patchable externals as well. Example ======= The following is an example. struct pt_regs { long arg1; long arg2; }; struct sk_buff { int i; struct net_device *dev; }; #define _(x) (__builtin_preserve_access_index(x)) static int (*bpf_probe_read)(void *dst, int size, const void *unsafe_ptr) = (void *) 4; extern __attribute__((section(".BPF.patchable_externs"))) unsigned __kernel_version; int bpf_prog(struct pt_regs *ctx) { struct net_device *dev = 0; // ctx->arg* does not need bpf_probe_read if (__kernel_version >= 41608) bpf_probe_read(&dev, sizeof(dev), _(&((struct sk_buff *)ctx->arg1)->dev)); else bpf_probe_read(&dev, sizeof(dev), _(&((struct sk_buff *)ctx->arg2)->dev)); return dev != 0; } In the above, we want to translate the third argument of bpf_probe_read() as relocations. -bash-4.4$ clang -target bpf -O2 -g -S trace.c The compiler will generate two new subsections in .BTF.ext, OffsetReloc and ExternReloc. OffsetReloc is to record the structure member offset operations, and ExternalReloc is to record the external globals where only u8, u16, u32 and u64 are supported. BPFOffsetReloc Size struct SecLOffsetReloc for ELF section #1 A number of struct BPFOffsetReloc for ELF section #1 struct SecOffsetReloc for ELF section #2 A number of struct BPFOffsetReloc for ELF section #2 ... BPFExternReloc Size struct SecExternReloc for ELF section #1 A number of struct BPFExternReloc for ELF section #1 struct SecExternReloc for ELF section #2 A number of struct BPFExternReloc for ELF section #2 struct BPFOffsetReloc { uint32_t InsnOffset; ///< Byte offset in this section uint32_t TypeID; ///< TypeID for the relocation uint32_t OffsetNameOff; ///< The string to traverse types }; struct BPFExternReloc { uint32_t InsnOffset; ///< Byte offset in this section uint32_t ExternNameOff; ///< The string for external variable }; Note that only externs with attribute section ".BPF.patchable_externs" are considered for Extern Reloc which will be patched by bpf loader right before the load. For the above test case, two offset records and one extern record will be generated: OffsetReloc records: .long .Ltmp12 # Insn Offset .long 7 # TypeId .long 242 # Type Decode String .long .Ltmp18 # Insn Offset .long 7 # TypeId .long 242 # Type Decode String ExternReloc record: .long .Ltmp5 # Insn Offset .long 165 # External Variable In string table: .ascii "0:1" # string offset=242 .ascii "__kernel_version" # string offset=165 The default member offset can be calculated as the 2nd member offset (0 representing the 1st member) of struct "sk_buff". The asm code: .Ltmp5: .Ltmp6: r2 = 0 r3 = 41608 .Ltmp7: .Ltmp8: .loc 1 18 9 is_stmt 0 # t.c:18:9 .Ltmp9: if r3 > r2 goto LBB0_2 .Ltmp10: .Ltmp11: .loc 1 0 9 # t.c:0:9 .Ltmp12: r2 = 8 .Ltmp13: .loc 1 19 66 is_stmt 1 # t.c:19:66 .Ltmp14: .Ltmp15: r3 = *(u64 *)(r1 + 0) goto LBB0_3 .Ltmp16: .Ltmp17: LBB0_2: .loc 1 0 66 is_stmt 0 # t.c:0:66 .Ltmp18: r2 = 8 .loc 1 21 66 is_stmt 1 # t.c:21:66 .Ltmp19: r3 = *(u64 *)(r1 + 8) .Ltmp20: .Ltmp21: LBB0_3: .loc 1 0 66 is_stmt 0 # t.c:0:66 r3 += r2 r1 = r10 .Ltmp22: .Ltmp23: .Ltmp24: r1 += -8 r2 = 8 call 4 For instruction .Ltmp12 and .Ltmp18, "r2 = 8", the number 8 is the structure offset based on the current BTF. Loader needs to adjust it if it changes on the host. For instruction .Ltmp5, "r2 = 0", the external variable got a default value 0, loader needs to supply an appropriate value for the particular host. Compiling to generate object code and disassemble: 0000000000000000 bpf_prog: 0: b7 02 00 00 00 00 00 00 r2 = 0 1: 7b 2a f8 ff 00 00 00 00 *(u64 *)(r10 - 8) = r2 2: b7 02 00 00 00 00 00 00 r2 = 0 3: b7 03 00 00 88 a2 00 00 r3 = 41608 4: 2d 23 03 00 00 00 00 00 if r3 > r2 goto +3 <LBB0_2> 5: b7 02 00 00 08 00 00 00 r2 = 8 6: 79 13 00 00 00 00 00 00 r3 = *(u64 *)(r1 + 0) 7: 05 00 02 00 00 00 00 00 goto +2 <LBB0_3> 0000000000000040 LBB0_2: 8: b7 02 00 00 08 00 00 00 r2 = 8 9: 79 13 08 00 00 00 00 00 r3 = *(u64 *)(r1 + 8) 0000000000000050 LBB0_3: 10: 0f 23 00 00 00 00 00 00 r3 += r2 11: bf a1 00 00 00 00 00 00 r1 = r10 12: 07 01 00 00 f8 ff ff ff r1 += -8 13: b7 02 00 00 08 00 00 00 r2 = 8 14: 85 00 00 00 04 00 00 00 call 4 Instructions #2, #5 and #8 need relocation resoutions from the loader. Signed-off-by: Yonghong Song <[email protected]> Differential Revision: https://reviews.llvm.org/D61524 llvm-svn: 365503
mgrang
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Feb 18, 2020
If a core file has an EFI version string which includes a UUID (similar to what it returns for the kdp KDP_KERNELVERSION packet) in the LC_IDENT or LC_NOTE 'kern ver str' load command. In that case, we should try to find the binary and dSYM for the UUID listed. The dSYM may have python code which knows how to relocate the binary to the correct address in lldb's target section load list and loads other ancillary binaries. The test case is a little involved, 1. it compiles an inferior hello world apple (a.out), 2. it compiles a program which can create a corefile manually with a specific binary's UUID encoded in it, 3. it gets the UUID of the a.out binary, 4. it creates a shell script, dsym-for-uuid.sh, which will return the full path to the a.out + a.out.dSYM when called with teh correct UUID, 5. it sets the LLDB_APPLE_DSYMFORUUID_EXECUTABLE env var before creating the lldb target, to point to this dsym-for-uuid.sh, 6. runs the create-corefile binary we compiled in step #2, 7. loads the corefile from step #6 into lldb, 8. verifies that lldb loaded a.out by reading the LC_NOTE load command from the corefile, calling dsym-for-uuid.sh with that UUID, got back the path to a.out and loaded it. whew! <rdar://problem/47562911> llvm-svn: 366378
kkjeer
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Sep 23, 2020
When `Target::GetEntryPointAddress()` calls `exe_module->GetObjectFile()->GetEntryPointAddress()`, and the returned `entry_addr` is valid, it can immediately be returned. However, just before that, an `llvm::Error` value has been setup, but in this case it is not consumed before returning, like is done further below in the function. In https://bugs.freebsd.org/248745 we got a bug report for this, where a very simple test case aborts and dumps core: ``` * thread #1, name = 'testcase', stop reason = breakpoint 1.1 frame #0: 0x00000000002018d4 testcase`main(argc=1, argv=0x00007fffffffea18) at testcase.c:3:5 1 int main(int argc, char *argv[]) 2 { -> 3 return 0; 4 } (lldb) p argc Program aborted due to an unhandled Error: Error value was Success. (Note: Success values must still be checked prior to being destroyed). Thread 1 received signal SIGABRT, Aborted. thr_kill () at thr_kill.S:3 3 thr_kill.S: No such file or directory. (gdb) bt #0 thr_kill () at thr_kill.S:3 #1 0x00000008049a0004 in __raise (s=6) at /usr/src/lib/libc/gen/raise.c:52 #2 0x0000000804916229 in abort () at /usr/src/lib/libc/stdlib/abort.c:67 #3 0x000000000451b5f5 in fatalUncheckedError () at /usr/src/contrib/llvm-project/llvm/lib/Support/Error.cpp:112 #4 0x00000000019cf008 in GetEntryPointAddress () at /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Error.h:267 #5 0x0000000001bccbd8 in ConstructorSetup () at /usr/src/contrib/llvm-project/lldb/source/Target/ThreadPlanCallFunction.cpp:67 #6 0x0000000001bcd2c0 in ThreadPlanCallFunction () at /usr/src/contrib/llvm-project/lldb/source/Target/ThreadPlanCallFunction.cpp:114 #7 0x00000000020076d4 in InferiorCallMmap () at /usr/src/contrib/llvm-project/lldb/source/Plugins/Process/Utility/InferiorCallPOSIX.cpp:97 #8 0x0000000001f4be33 in DoAllocateMemory () at /usr/src/contrib/llvm-project/lldb/source/Plugins/Process/FreeBSD/ProcessFreeBSD.cpp:604 #9 0x0000000001fe51b9 in AllocatePage () at /usr/src/contrib/llvm-project/lldb/source/Target/Memory.cpp:347 #10 0x0000000001fe5385 in AllocateMemory () at /usr/src/contrib/llvm-project/lldb/source/Target/Memory.cpp:383 #11 0x0000000001974da2 in AllocateMemory () at /usr/src/contrib/llvm-project/lldb/source/Target/Process.cpp:2301 #12 CanJIT () at /usr/src/contrib/llvm-project/lldb/source/Target/Process.cpp:2331 #13 0x0000000001a1bf3d in Evaluate () at /usr/src/contrib/llvm-project/lldb/source/Expression/UserExpression.cpp:190 #14 0x00000000019ce7a2 in EvaluateExpression () at /usr/src/contrib/llvm-project/lldb/source/Target/Target.cpp:2372 #15 0x0000000001ad784c in EvaluateExpression () at /usr/src/contrib/llvm-project/lldb/source/Commands/CommandObjectExpression.cpp:414 #16 0x0000000001ad86ae in DoExecute () at /usr/src/contrib/llvm-project/lldb/source/Commands/CommandObjectExpression.cpp:646 #17 0x0000000001a5e3ed in Execute () at /usr/src/contrib/llvm-project/lldb/source/Interpreter/CommandObject.cpp:1003 #18 0x0000000001a6c4a3 in HandleCommand () at /usr/src/contrib/llvm-project/lldb/source/Interpreter/CommandInterpreter.cpp:1762 #19 0x0000000001a6f98c in IOHandlerInputComplete () at /usr/src/contrib/llvm-project/lldb/source/Interpreter/CommandInterpreter.cpp:2760 #20 0x0000000001a90b08 in Run () at /usr/src/contrib/llvm-project/lldb/source/Core/IOHandler.cpp:548 #21 0x00000000019a6c6a in ExecuteIOHandlers () at /usr/src/contrib/llvm-project/lldb/source/Core/Debugger.cpp:903 #22 0x0000000001a70337 in RunCommandInterpreter () at /usr/src/contrib/llvm-project/lldb/source/Interpreter/CommandInterpreter.cpp:2946 #23 0x0000000001d9d812 in RunCommandInterpreter () at /usr/src/contrib/llvm-project/lldb/source/API/SBDebugger.cpp:1169 #24 0x0000000001918be8 in MainLoop () at /usr/src/contrib/llvm-project/lldb/tools/driver/Driver.cpp:675 #25 0x000000000191a114 in main () at /usr/src/contrib/llvm-project/lldb/tools/driver/Driver.cpp:890``` Fix the incorrect error catch by only instantiating an `Error` object if it is necessary. Reviewed By: JDevlieghere Differential Revision: https://reviews.llvm.org/D86355 (cherry picked from commit 1ce07cd)
kkjeer
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Feb 20, 2021
… Solaris/x86
A dozen 32-bit `AddressSanitizer` testcases FAIL on the latest beta of Solaris 11.4/x86, e.g.
`AddressSanitizer-i386-sunos :: TestCases/null_deref.cpp` produces
AddressSanitizer:DEADLYSIGNAL
=================================================================
==29274==ERROR: AddressSanitizer: stack-overflow on address 0x00000028 (pc 0x08135efd bp 0xfeffdfd8 sp 0x00000000 T0)
#0 0x8135efd in NullDeref(int*) /vol/llvm/src/llvm-project/dist/compiler-rt/test/asan/TestCases/null_deref.cpp:15:10
#1 0x8135ea6 in main /vol/llvm/src/llvm-project/dist/compiler-rt/test/asan/TestCases/null_deref.cpp:21:3
#2 0x8084b85 in _start (null_deref.cpp.tmp+0x8084b85)
SUMMARY: AddressSanitizer: stack-overflow /vol/llvm/src/llvm-project/dist/compiler-rt/test/asan/TestCases/null_deref.cpp:15:10 in NullDeref(int*)
==29274==ABORTING
instead of the expected
AddressSanitizer:DEADLYSIGNAL
=================================================================
==29276==ERROR: AddressSanitizer: SEGV on unknown address 0x00000028 (pc 0x08135f1f bp 0xfeffdf48 sp 0xfeffdf40 T0)
==29276==The signal is caused by a WRITE memory access.
==29276==Hint: address points to the zero page.
#0 0x8135f1f in NullDeref(int*) /vol/llvm/src/llvm-project/local/compiler-rt/test/asan/TestCases/null_deref.cpp:15:10
#1 0x8135efa in main /vol/llvm/src/llvm-project/local/compiler-rt/test/asan/TestCases/null_deref.cpp:21:3
#2 0x8084be5 in _start (null_deref.cpp.tmp+0x8084be5)
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /vol/llvm/src/llvm-project/local/compiler-rt/test/asan/TestCases/null_deref.cpp:15:10 in NullDeref(int*)
==29276==ABORTING
I managed to trace this to a change in `<sys/regset.h>`: previously the header would
primarily define the short register indices (like `UESP`). While they are required by the
i386 psABI, they are only required in `<ucontext.h>` and could previously leak into
unsuspecting user code, polluting the namespace and requiring elaborate workarounds
like that in `llvm/include/llvm/Support/Solaris/sys/regset.h`. The change fixed that by restricting
the definition of the short forms appropriately, at the same time defining all `REG_` prefixed
forms for compatiblity with other systems. This exposed a bug in `compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp`, however:
Previously, the index for the user stack pointer would be hardcoded if `REG_ESP`
wasn't defined. Now with that definition present, it turned out that `REG_ESP` was the wrong index to use: the previous value 17 (and `REG_SP`) corresponds to `REG_UESP`
instead.
With that change, the failures are all gone.
Tested on `amd-pc-solaris2.11`.
Differential Revision: https://reviews.llvm.org/D83664
sulekhark
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Apr 25, 2021
…t-extended register offsets. The G_ZEXT in these cases seems to actually come from a combine that we do but SelectionDAG doesn't. Looking through it allows us to match "uxtw #2" addressing modes. Differential Revision: https://reviews.llvm.org/D91475 (cherry picked from commit 0b60906)
sulekhark
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Aug 2, 2021
… disabled for a PCH vs a module file This addresses an issue with how the PCH preable works, specifically: 1. When using a PCH/preamble the module hash changes and a different cache directory is used 2. When the preamble is used, PCH & PCM validation is disabled. Due to combination of #1 and #2, reparsing with preamble enabled can end up loading a stale module file before a header change and using it without updating it because validation is disabled and it doesn’t check that the header has changed and the module file is out-of-date. rdar://72611253 Differential Revision: https://reviews.llvm.org/D95159
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Fix a few typos in Setup-and-Build.md. Add a missing
hyperlink for how to update to newer versions of the
LLVM/clang sources.