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* [BPF] Don't fail for static variablesYonghong Song2019-02-271-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, the LLVM will print an error like Unsupported relocation: try to compile with -O2 or above, or check your static variable usage if user defines more than one static variables in a single ELF section (e.g., .bss or .data). There is ongoing effort to support static and global variables in libbpf and kernel. This patch removed the assertion so user programs with static variables won't fail compilation. The static variable in-section offset is written to the "imm" field of the corresponding to-be-relocated bpf instruction. Below is an example to show how the application (e.g., libbpf) can relate variable to relocations. -bash-4.4$ cat g1.c static volatile long a = 2; static volatile int b = 3; int test() { return a + b; } -bash-4.4$ clang -target bpf -O2 -c g1.c -bash-4.4$ llvm-readelf -r g1.o Relocation section '.rel.text' at offset 0x158 contains 2 entries: Offset Info Type Symbol's Value Symbol's Name 0000000000000000 0000000400000001 R_BPF_64_64 0000000000000000 .data 0000000000000018 0000000400000001 R_BPF_64_64 0000000000000000 .data -bash-4.4$ llvm-readelf -s g1.o Symbol table '.symtab' contains 6 entries: Num: Value Size Type Bind Vis Ndx Name 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND 1: 0000000000000000 0 FILE LOCAL DEFAULT ABS g1.c 2: 0000000000000000 8 OBJECT LOCAL DEFAULT 4 a 3: 0000000000000008 4 OBJECT LOCAL DEFAULT 4 b 4: 0000000000000000 0 SECTION LOCAL DEFAULT 4 5: 0000000000000000 64 FUNC GLOBAL DEFAULT 2 test -bash-4.4$ llvm-objdump -d g1.o g1.o: file format ELF64-BPF Disassembly of section .text: 0000000000000000 test: 0: 18 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r1 = 0 ll 2: 79 11 00 00 00 00 00 00 r1 = *(u64 *)(r1 + 0) 3: 18 02 00 00 08 00 00 00 00 00 00 00 00 00 00 00 r2 = 8 ll 5: 61 20 00 00 00 00 00 00 r0 = *(u32 *)(r2 + 0) 6: 0f 10 00 00 00 00 00 00 r0 += r1 7: 95 00 00 00 00 00 00 00 exit -bash-4.4$ . from symbol table, static variable "a" is in section #4, offset 0. . from symbol table, static variable "b" is in section #4, offset 8. . the first relocation is against symbol #4: 4: 0000000000000000 0 SECTION LOCAL DEFAULT 4 and in-section offset 0 (see llvm-objdump result) . the second relocation is against symbol #4: 4: 0000000000000000 0 SECTION LOCAL DEFAULT 4 and in-section offset 8 (see llvm-objdump result) . therefore, the first relocation is for variable "a", and the second relocation is for variable "b". Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Yonghong Song <yhs@fb.com> llvm-svn: 354954
* Update the file headers across all of the LLVM projects in the monorepoChandler Carruth2019-01-191-4/+3
| | | | | | | | | | | | | | | | | to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
* bpf: fix an assertion in BPFAsmBackend applyFixup()Yonghong Song2018-08-221-1/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix bug https://bugs.llvm.org/show_bug.cgi?id=38643 In BPFAsmBackend applyFixup(), there is an assertion for FixedValue to be 0. This may not be true, esp. for optimiation level 0. For example, in the above bug, for the following two static variables: @bpf_map_lookup_elem = internal global i8* (i8*, i8*)* inttoptr (i64 1 to i8* (i8*, i8*)*), align 8 @bpf_map_update_elem = internal global i32 (i8*, i8*, i8*, i64)* inttoptr (i64 2 to i32 (i8*, i8*, i8*, i64)*), align 8 The static variable @bpf_map_update_elem will have a symbol offset of 8 and a FK_SecRel_8 with FixupValue 8 will cause the assertion if llvm is built with -DLLVM_ENABLE_ASSERTIONS=ON. The above relocations will not exist if the program is compiled with optimization level -O1 and above as the compiler optimizes those static variables away. In the below error message, -O2 is suggested as this is the common practice. Note that FixedValue = 0 in applyFixup() does exist and is valid, e.g., for the global variable my_map in the above bug. The bpf loader will process them properly for map_id's before loading the program into the kernel. The static variables, which are not optimized away by compiler, may have FK_SecRel_8 relocation with non-zero FixedValue. The patch removed the offending assertion and will issue a hard error as below if the FixedValue in applyFixup() is not 0. $ llc -march=bpf -filetype=obj fixup.ll LLVM ERROR: Unsupported relocation: try to compile with -O2 or above, or check your static variable usage Signed-off-by: Yonghong Song <yhs@fb.com> llvm-svn: 340455
* [MC] Pass MCSubtargetInfo to fixupNeedsRelaxation and applyFixupPeter Smith2018-06-061-3/+8
| | | | | | | | | | | | | | | | | | On targets like Arm some relaxations may only be performed when certain architectural features are available. As functions can be compiled with differing levels of architectural support we must make a judgement on whether we can relax based on the MCSubtargetInfo for the function. This change passes through the MCSubtargetInfo for the function to fixupNeedsRelaxation so that the decision on whether to relax can be made per function. In this patch, only the ARM backend makes use of this information. We must also pass the MCSubtargetInfo to applyFixup because some fixups skip error checking on the assumption that relaxation has occurred, to prevent code-generation errors applyFixup must see the same MCSubtargetInfo as fixupNeedsRelaxation. Differential Revision: https://reviews.llvm.org/D44928 llvm-svn: 334078
* MC: Separate creating a generic object writer from creating a target object ↵Peter Collingbourne2018-05-211-5/+5
| | | | | | | | | | | | | writer. NFCI. With this we gain a little flexibility in how the generic object writer is created. Part of PR37466. Differential Revision: https://reviews.llvm.org/D47045 llvm-svn: 332868
* MC: Change MCAsmBackend::writeNopData() to take a raw_ostream instead of an ↵Peter Collingbourne2018-05-211-25/+15
| | | | | | | | | | | | | MCObjectWriter. NFCI. To make this work I needed to add an endianness field to MCAsmBackend so that writeNopData() implementations know which endianness to use. Part of PR37466. Differential Revision: https://reviews.llvm.org/D47035 llvm-svn: 332857
* Thread MCSubtargetInfo through Target::createMCAsmBackendAlex Bradbury2018-01-031-4/+4
| | | | | | | | | | | | | | | | | | | | | Currently it's not possible to access MCSubtargetInfo from a TgtMCAsmBackend. D20830 threaded an MCSubtargetInfo reference through MCAsmBackend::relaxInstruction, but this isn't the only function that would benefit from access. This patch removes the Triple and CPUString arguments from createMCAsmBackend and replaces them with MCSubtargetInfo. This patch just changes the interface without making any intentional functional changes. Once in, several cleanups are possible: * Get rid of the awkward MCSubtargetInfo handling in ARMAsmBackend * Support 16-bit instructions when valid in MipsAsmBackend::writeNopData * Get rid of the CPU string parsing in X86AsmBackend and just use a SubtargetFeature for HasNopl * Emit 16-bit nops in RISCVAsmBackend::writeNopData if the compressed instruction set extension is enabled (see D41221) This change initially exposed PR35686, which has since been resolved in r321026. Differential Revision: https://reviews.llvm.org/D41349 llvm-svn: 321692
* [bpf] allow direct and indirect callsAlexei Starovoitov2017-11-191-0/+9
| | | | | | | | | | | | | | | kernel verifier is becoming smarter and soon will support direct and indirect function calls. Remove obsolete error from BPF backend. Make call to use PCRel_4 fixup. 'bpf to bpf' calls are distinguished from 'bpf to kernel' calls by insn->src_reg == BPF_PSEUDO_CALL == 1 which is used as relocation indicator similar to ld_imm64->src_reg == BPF_PSEUDO_MAP_FD == 1 The actual 'call' instruction remains the same for both 'bpf to kernel' and 'bpf to bpf' calls. Signed-off-by: Alexei Starovoitov <ast@kernel.org> llvm-svn: 318614
* [MC] Thread unique_ptr<MCObjectWriter> through the create.*ObjectWriterLang Hames2017-10-101-2/+4
| | | | | | | | | | functions. This makes the ownership of the resulting MCObjectWriter clear, and allows us to remove one instance of MCObjectStreamer's bizarre "holding ownership via someone else's reference" trick. llvm-svn: 315327
* Fully fix the movw/movt addend.Rafael Espindola2017-07-111-2/+2
| | | | | | | | | | The issue is not if the value is pcrel. It is whether we have a relocation or not. If we have a relocation, the static linker will select the upper bits. If we don't have a relocation, we have to do it. llvm-svn: 307730
* Remove redundant argument.Rafael Espindola2017-06-241-2/+2
| | | | llvm-svn: 306189
* ARM: move some logic from processFixupValue to applyFixup.Rafael Espindola2017-06-231-4/+6
| | | | | | | | | | | | processFixupValue is called on every relaxation iteration. applyFixup is only called once at the very end. applyFixup is then the correct place to do last minute changes and value checks. While here, do proper range checks again for fixup_arm_thumb_bl. We used to do it, but dropped because of thumb2. We now do it again, but use the thumb2 range. llvm-svn: 306177
* Use a MutableArrayRef. NFC.Rafael Espindola2017-06-211-3/+3
| | | | llvm-svn: 305968
* [bpf] fix a bug which causes incorrect big endian reloc fixupAlexei Starovoitov2017-05-051-1/+1
| | | | | | | | o Add bpfeb support in BPF dwarfdump unit test case Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@fb.com> llvm-svn: 302265
* Add MCContext argument to MCAsmBackend::applyFixup for error reportingAlex Bradbury2017-04-051-3/+3
| | | | | | | | | | | | | | | | A number of backends (AArch64, MIPS, ARM) have been using MCContext::reportError to report issues such as out-of-range fixup values in their TgtAsmBackend. This is great, but because MCContext couldn't easily be threaded through to the adjustFixupValue helper function from its usual callsite (applyFixup), these backends ended up adding an MCContext* argument and adding another call to applyFixup to processFixupValue. Adding an MCContext parameter to applyFixup makes this unnecessary, and even better - applyFixup can take a reference to MCContext rather than a potentially null pointer. Differential Revision: https://reviews.llvm.org/D30264 llvm-svn: 299529
* [BPF] Fix some Clang-tidy modernize and Include What You Use warnings; other ↵Eugene Zelenko2017-01-061-12/+8
| | | | | | minor fixes (NFC). llvm-svn: 291297
* MC] Provide an MCTargetOptions to implementors of MCAsmBackendCtorTy, NFCJoel Jones2016-07-251-2/+4
| | | | | | | | | | | | | | | Some targets, notably AArch64 for ILP32, have different relocation encodings based upon the ABI. This is an enabling change, so a future patch can use the ABIName from MCTargetOptions to chose which relocations to use. Tested using check-llvm. The corresponding change to clang is in: http://reviews.llvm.org/D16538 Patch by: Joel Jones Differential Revision: https://reviews.llvm.org/D16213 llvm-svn: 276654
* Fix branch relaxation in 16-bit mode.Nirav Dave2016-07-111-1/+2
| | | | | | | | | | | | | | | Thread through MCSubtargetInfo to relaxInstruction function allowing relaxation to generate jumps with 16-bit sized immediates in 16-bit mode. This fixes PR22097. Reviewers: dwmw2, tstellarAMD, craig.topper, jyknight Subscribers: jfb, arsenm, jyknight, llvm-commits, dsanders Differential Revision: http://reviews.llvm.org/D20830 llvm-svn: 275068
* Revert r247692: Replace Triple with a new TargetTuple in MCTargetDesc/* and ↵Daniel Sanders2015-09-151-3/+2
| | | | | | | | related. NFC. Eric has replied and has demanded the patch be reverted. llvm-svn: 247702
* Re-commit r247683: Replace Triple with a new TargetTuple in MCTargetDesc/* ↵Daniel Sanders2015-09-151-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | and related. NFC. Summary: This is the first patch in the series to migrate Triple's (which are ambiguous) to TargetTuple's (which aren't). For the moment, TargetTuple simply passes all requests to the Triple object it holds. Once it has replaced Triple, it will start to implement the interface in a more suitable way. This change makes some changes to the public C++ API. In particular, InitMCSubtargetInfo(), createMCRelocationInfo(), and createMCSymbolizer() now take TargetTuples instead of Triples. The other public C++ API's have been left as-is for the moment to reduce patch size. This commit also contains a trivial patch to clang to account for the C++ API change. Thanks go to Pavel Labath for fixing LLDB for me. Reviewers: rengolin Subscribers: jyknight, dschuff, arsenm, rampitec, danalbert, srhines, javed.absar, dsanders, echristo, emaste, jholewinski, tberghammer, ted, jfb, llvm-commits, rengolin Differential Revision: http://reviews.llvm.org/D10969 llvm-svn: 247692
* Revert r247684 - Replace Triple with a new TargetTuple ...Daniel Sanders2015-09-151-3/+2
| | | | | | LLDB needs to be updated in the same commit. llvm-svn: 247686
* Replace Triple with a new TargetTuple in MCTargetDesc/* and related. NFC.Daniel Sanders2015-09-151-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This is the first patch in the series to migrate Triple's (which are ambiguous) to TargetTuple's (which aren't). For the moment, TargetTuple simply passes all requests to the Triple object it holds. Once it has replaced Triple, it will start to implement the interface in a more suitable way. This change makes some changes to the public C++ API. In particular, InitMCSubtargetInfo(), createMCRelocationInfo(), and createMCSymbolizer() now take TargetTuples instead of Triples. The other public C++ API's have been left as-is for the moment to reduce patch size. This commit also contains a trivial patch to clang to account for the C++ API change. Reviewers: rengolin Subscribers: jyknight, dschuff, arsenm, rampitec, danalbert, srhines, javed.absar, dsanders, echristo, emaste, jholewinski, tberghammer, ted, jfb, llvm-commits, rengolin Differential Revision: http://reviews.llvm.org/D10969 llvm-svn: 247683
* [bpf] initial support for debug_infoAlexei Starovoitov2015-07-241-9/+16
| | | | llvm-svn: 243087
* Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC)Alexander Kornienko2015-06-231-1/+1
| | | | | | Apparently, the style needs to be agreed upon first. llvm-svn: 240390
* Fixed/added namespace ending comments using clang-tidy. NFCAlexander Kornienko2015-06-191-1/+1
| | | | | | | | | | | | | The patch is generated using this command: tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \ -checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \ llvm/lib/ Thanks to Eugene Kosov for the original patch! llvm-svn: 240137
* Replace string GNU Triples with llvm::Triple in MCAsmBackend subclasses and ↵Daniel Sanders2015-06-101-4/+4
| | | | | | | | | | | | | | | | | | create*AsmBackend(). NFC. Summary: This continues the patch series to eliminate StringRef forms of GNU triples from the internals of LLVM that began in r239036. Reviewers: echristo, rafael Reviewed By: rafael Subscribers: rafael, llvm-commits, rengolin Differential Revision: http://reviews.llvm.org/D10243 llvm-svn: 239464
* MC: Clean up naming in MCObjectWriter. NFC.Jim Grosbach2015-06-041-1/+1
| | | | | | | | | | | | | | | | | | | | s/WriteObject/writeObject/ s/RecordRelocation/recordRelocation/ s/IsSymbolRefDifferenceFullyResolved/isSymbolRefDifferenceFullyResolved/ s/Write8/write8/ s/WriteLE16/writeLE16/ s/WriteLE32/writeLE32/ s/WriteLE64/writeLE64/ s/WriteBE16/writeBE16/ s/WriteBE32/writeBE32/ s/WriteBE64/writeBE64/ s/Write16/write16/ s/Write32/write32/ s/Write64/write64/ s/WriteZeroes/writeZeroes/ s/WriteBytes/writeBytes/ llvm-svn: 239108
* [bpf] add big- and host- endian supportAlexei Starovoitov2015-06-041-5/+19
| | | | | | | | | | | | | | | | | | | Summary: -march=bpf -> host endian -march=bpf_le -> little endian -match=bpf_be -> big endian Test Plan: v1 was tested by IBM s390 guys and appears to be working there. It bit rots too fast here. Reviewers: chandlerc, tstellarAMD Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D10177 llvm-svn: 239071
* [bpf] emit jmp fixups in little endianAlexei Starovoitov2015-05-221-1/+3
| | | | | | | | The 'off' field of 'struct bpf_insn' is in cpu-endianness, since the rest is emitted as little endian, make sure that 'off' field is little endian as well. llvm-svn: 238038
* [bpf] fix buildAlexei Starovoitov2015-04-151-2/+2
| | | | | | fix build due to refactoring in DIL/MDL and raw_pwrite_stream llvm-svn: 234971
* BPF backendAlexei Starovoitov2015-01-241-0/+83
Summary: V8->V9: - cleanup tests V7->V8: - addressed feedback from David: - switched to range-based 'for' loops - fixed formatting of tests V6->V7: - rebased and adjusted AsmPrinter args - CamelCased .td, fixed formatting, cleaned up names, removed unused patterns - diffstat: 3 files changed, 203 insertions(+), 227 deletions(-) V5->V6: - addressed feedback from Chandler: - reinstated full verbose standard banner in all files - fixed variables that were not in CamelCase - fixed names of #ifdef in header files - removed redundant braces in if/else chains with single statements - fixed comments - removed trailing empty line - dropped debug annotations from tests - diffstat of these changes: 46 files changed, 456 insertions(+), 469 deletions(-) V4->V5: - fix setLoadExtAction() interface - clang-formated all where it made sense V3->V4: - added CODE_OWNERS entry for BPF backend V2->V3: - fix metadata in tests V1->V2: - addressed feedback from Tom and Matt - removed top level change to configure (now everything via 'experimental-backend') - reworked error reporting via DiagnosticInfo (similar to R600) - added few more tests - added cmake build - added Triple::bpf - tested on linux and darwin V1 cover letter: --------------------- recently linux gained "universal in-kernel virtual machine" which is called eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since new instruction set is based on it. This patch adds a new backend that emits extended BPF instruction set. The concept and development are covered by the following articles: http://lwn.net/Articles/599755/ http://lwn.net/Articles/575531/ http://lwn.net/Articles/603983/ http://lwn.net/Articles/606089/ http://lwn.net/Articles/612878/ One of use cases: dtrace/systemtap alternative. bpf syscall manpage: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe instruction set description and differences vs classic BPF: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt Short summary of instruction set: - 64-bit registers R0 - return value from in-kernel function, and exit value for BPF program R1 - R5 - arguments from BPF program to in-kernel function R6 - R9 - callee saved registers that in-kernel function will preserve R10 - read-only frame pointer to access stack - two-operand instructions like +, -, *, mov, load/store - implicit prologue/epilogue (invisible stack pointer) - no floating point, no simd Short history of extended BPF in kernel: interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future. It's a very small and simple backend. There is no support for global variables, arbitrary function calls, floating point, varargs, exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc. From C front-end point of view it's very restricted. It's done on purpose, since kernel rejects all programs that it cannot prove safe. It rejects programs with loops and with memory accesses via arbitrary pointers. When kernel accepts the program it is guaranteed that program will terminate and will not crash the kernel. This patch implements all 'must have' bits. There are several things on TODO list, so this is not the end of development. Most of the code is a boiler plate code, copy-pasted from other backends. Only odd things are lack or < and <= instructions, specialized load_byte intrinsics and 'compare and goto' as single instruction. Current instruction set is fixed, but more instructions can be added in the future. Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits Differential Revision: http://reviews.llvm.org/D6494 llvm-svn: 227008
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