summaryrefslogtreecommitdiffstats
path: root/clang/lib/Basic/Targets/BPF.h
Commit message (Collapse)AuthorAgeFilesLines
* reland "[DebugInfo] Support to emit debugInfo for extern variables"Yonghong Song2019-12-221-0/+2
| | | | | | | | | | | | | Commit d77ae1552fc21a9f3877f3ed7e13d631f517c825 ("[DebugInfo] Support to emit debugInfo for extern variables") added deebugInfo for extern variables for BPF target. The commit is reverted by 891e25b02d760d0de18c7d46947913b3166047e7 as the committed tests using %clang instead of %clang_cc1 causing test failed in certain scenarios as reported by Reid Kleckner. This patch fixed the tests by using %clang_cc1. Differential Revision: https://reviews.llvm.org/D71818
* Revert "[DebugInfo] Support to emit debugInfo for extern variables"Reid Kleckner2019-12-221-2/+0
| | | | | | | This reverts commit d77ae1552fc21a9f3877f3ed7e13d631f517c825. The tests committed along with this change do not pass, and should be changed to use %clang_cc1.
* [DebugInfo] Support to emit debugInfo for extern variablesYonghong Song2019-12-101-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Extern variable usage in BPF is different from traditional pure user space application. Recent discussion in linux bpf mailing list has two use cases where debug info types are required to use extern variables: - extern types are required to have a suitable interface in libbpf (bpf loader) to provide kernel config parameters to bpf programs. https://lore.kernel.org/bpf/CAEf4BzYCNo5GeVGMhp3fhysQ=_axAf=23PtwaZs-yAyafmXC9g@mail.gmail.com/T/#t - extern types are required so kernel bpf verifier can verify program which uses external functions more precisely. This will make later link with actual external function no need to reverify. https://lore.kernel.org/bpf/87eez4odqp.fsf@toke.dk/T/#m8d5c3e87ffe7f2764e02d722cb0d8cbc136880ed This patch added clang support to emit debuginfo for extern variables with a TargetInfo hook to enable it. The debuginfo for the extern variable is emitted only if that extern variable is referenced in the current compilation unit. Currently, only BPF target enables to generate debug info for extern variables. The emission of such debuginfo is disabled for C++ at this moment since BPF only supports a subset of C language. Emission with C++ can be enabled later if an appropriate use case is identified. -fstandalone-debug permits us to see more debuginfo with the cost of bloated binary size. This patch did not add emission of extern variable debug info with -fstandalone-debug. This can be re-evaluated if there is a real need. Differential Revision: https://reviews.llvm.org/D70696
* [BPF] do compile-once run-everywhere relocation for bitfieldsYonghong Song2019-10-081-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A bpf specific clang intrinsic is introduced: u32 __builtin_preserve_field_info(member_access, info_kind) Depending on info_kind, different information will be returned to the program. A relocation is also recorded for this builtin so that bpf loader can patch the instruction on the target host. This clang intrinsic is used to get certain information to facilitate struct/union member relocations. The offset relocation is extended by 4 bytes to include relocation kind. Currently supported relocation kinds are enum { FIELD_BYTE_OFFSET = 0, FIELD_BYTE_SIZE, FIELD_EXISTENCE, FIELD_SIGNEDNESS, FIELD_LSHIFT_U64, FIELD_RSHIFT_U64, }; for __builtin_preserve_field_info. The old access offset relocation is covered by FIELD_BYTE_OFFSET = 0. An example: struct s { int a; int b1:9; int b2:4; }; enum { FIELD_BYTE_OFFSET = 0, FIELD_BYTE_SIZE, FIELD_EXISTENCE, FIELD_SIGNEDNESS, FIELD_LSHIFT_U64, FIELD_RSHIFT_U64, }; void bpf_probe_read(void *, unsigned, const void *); int field_read(struct s *arg) { unsigned long long ull = 0; unsigned offset = __builtin_preserve_field_info(arg->b2, FIELD_BYTE_OFFSET); unsigned size = __builtin_preserve_field_info(arg->b2, FIELD_BYTE_SIZE); #ifdef USE_PROBE_READ bpf_probe_read(&ull, size, (const void *)arg + offset); unsigned lshift = __builtin_preserve_field_info(arg->b2, FIELD_LSHIFT_U64); #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ lshift = lshift + (size << 3) - 64; #endif #else switch(size) { case 1: ull = *(unsigned char *)((void *)arg + offset); break; case 2: ull = *(unsigned short *)((void *)arg + offset); break; case 4: ull = *(unsigned int *)((void *)arg + offset); break; case 8: ull = *(unsigned long long *)((void *)arg + offset); break; } unsigned lshift = __builtin_preserve_field_info(arg->b2, FIELD_LSHIFT_U64); #endif ull <<= lshift; if (__builtin_preserve_field_info(arg->b2, FIELD_SIGNEDNESS)) return (long long)ull >> __builtin_preserve_field_info(arg->b2, FIELD_RSHIFT_U64); return ull >> __builtin_preserve_field_info(arg->b2, FIELD_RSHIFT_U64); } There is a minor overhead for bpf_probe_read() on big endian. The code and relocation generated for field_read where bpf_probe_read() is used to access argument data on little endian mode: r3 = r1 r1 = 0 r1 = 4 <=== relocation (FIELD_BYTE_OFFSET) r3 += r1 r1 = r10 r1 += -8 r2 = 4 <=== relocation (FIELD_BYTE_SIZE) call bpf_probe_read r2 = 51 <=== relocation (FIELD_LSHIFT_U64) r1 = *(u64 *)(r10 - 8) r1 <<= r2 r2 = 60 <=== relocation (FIELD_RSHIFT_U64) r0 = r1 r0 >>= r2 r3 = 1 <=== relocation (FIELD_SIGNEDNESS) if r3 == 0 goto LBB0_2 r1 s>>= r2 r0 = r1 LBB0_2: exit Compare to the above code between relocations FIELD_LSHIFT_U64 and FIELD_LSHIFT_U64, the code with big endian mode has four more instructions. r1 = 41 <=== relocation (FIELD_LSHIFT_U64) r6 += r1 r6 += -64 r6 <<= 32 r6 >>= 32 r1 = *(u64 *)(r10 - 8) r1 <<= r6 r2 = 60 <=== relocation (FIELD_RSHIFT_U64) The code and relocation generated when using direct load. r2 = 0 r3 = 4 r4 = 4 if r4 s> 3 goto LBB0_3 if r4 == 1 goto LBB0_5 if r4 == 2 goto LBB0_6 goto LBB0_9 LBB0_6: # %sw.bb1 r1 += r3 r2 = *(u16 *)(r1 + 0) goto LBB0_9 LBB0_3: # %entry if r4 == 4 goto LBB0_7 if r4 == 8 goto LBB0_8 goto LBB0_9 LBB0_8: # %sw.bb9 r1 += r3 r2 = *(u64 *)(r1 + 0) goto LBB0_9 LBB0_5: # %sw.bb r1 += r3 r2 = *(u8 *)(r1 + 0) goto LBB0_9 LBB0_7: # %sw.bb5 r1 += r3 r2 = *(u32 *)(r1 + 0) LBB0_9: # %sw.epilog r1 = 51 r2 <<= r1 r1 = 60 r0 = r2 r0 >>= r1 r3 = 1 if r3 == 0 goto LBB0_11 r2 s>>= r1 r0 = r2 LBB0_11: # %sw.epilog exit Considering verifier is able to do limited constant propogation following branches. The following is the code actually traversed. r2 = 0 r3 = 4 <=== relocation r4 = 4 <=== relocation if r4 s> 3 goto LBB0_3 LBB0_3: # %entry if r4 == 4 goto LBB0_7 LBB0_7: # %sw.bb5 r1 += r3 r2 = *(u32 *)(r1 + 0) LBB0_9: # %sw.epilog r1 = 51 <=== relocation r2 <<= r1 r1 = 60 <=== relocation r0 = r2 r0 >>= r1 r3 = 1 if r3 == 0 goto LBB0_11 r2 s>>= r1 r0 = r2 LBB0_11: # %sw.epilog exit For native load case, the load size is calculated to be the same as the size of load width LLVM otherwise used to load the value which is then used to extract the bitfield value. Differential Revision: https://reviews.llvm.org/D67980 llvm-svn: 374099
* 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: recognize target specific option -mattr=dwarfris in clangYonghong Song2018-06-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | | The following is the usage example with clang: bash-4.2$ clang -target bpf -O2 -g -c -Xclang -target-feature -Xclang +dwarfris t.c bash-4.2$ llvm-objdump -S -d t.o t.o: file format ELF64-BPF Disassembly of section .text: test: ; int test(void) { 0: b7 00 00 00 00 00 00 00 r0 = 0 ; return 0; 1: 95 00 00 00 00 00 00 00 exit bash-4.2$ cat t.c int test(void) { return 0; } bash-4.2$ Signed-off-by: Yonghong Song <yhs@fb.com> llvm-svn: 334839
* bpf: accept all asm register namesYonghong Song2018-04-111-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Sometimes when people compile bpf programs with "clang ... -target bpf ...", the kernel header files may contain host arch inline assembly codes as in the patch https://patchwork.kernel.org/patch/10119683/ by Arnaldo Carvaldo de Melo. The current workaround in the above patch is to guard the inline assembly with "#ifndef __BPF__" marco. So when __BPF__ is defined, these macros will have no use. Such a method is not extensible. As a matter of fact, most of these inline assembly codes will be thrown away at the end of clang compilation. So for bpf target, this patch accepts all asm register names in clang AST stage. The name will be checked again during llc code generation if the inline assembly code is indeed for bpf programs. With this patch, the above "#ifndef __BPF__" is not needed any more in https://patchwork.kernel.org/patch/10119683/. Signed-off-by: Yonghong Song <yhs@fb.com> llvm-svn: 329823
* bpf: Hook target feature "alu32" with LLVMYonghong Song2018-02-231-1/+8
| | | | | | | | | | | | | | LLVM has supported a new target feature "alu32" which could be enabled or disabled by "-mattr=[+|-]alu32" when using llc. This patch link Clang with it, so it could be also done by passing related options to Clang, for example: -Xclang -target-feature -Xclang +alu32 Signed-off-by: Jiong Wang <jiong.wang@netronome.com> Reviewed-by: Yonghong Song <yhs@fb.com> llvm-svn: 325996
* Add Rest of Targets Support to ValidCPUList (enabling march notes)Erich Keane2018-02-081-6/+3
| | | | | | | | | | | A followup to: https://reviews.llvm.org/D42978 Most of the rest of the Targets were pretty rote, so this patch knocks them all out at once. Differential Revision: https://reviews.llvm.org/D43057 llvm-svn: 324676
* bpf: add -mcpu=# support for bpfYonghong Song2017-08-231-0/+12
| | | | | | | | | | | | | | | | | | | | | -mcpu=# will support: . generic: the default insn set . v1: insn set version 1, the same as generic . v2: insn set version 2, version 1 + additional jmp insns . probe: the compiler will probe the underlying kernel to decide proper version of insn set. Examples: $ clang -target bpf -mcpu=v1 -c t.c $ clang -target bpf -mcpu=v2 -c t.c $ clang -target bpf -mcpu=generic -c t.c $ clang -target bpf -mcpu=probe -c t.c $ clang -target bpf -mcpu=v3 -c t.c error: unknown target CPU 'v3' Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> llvm-svn: 311523
* Break up Targets.cpp into a header/impl pair per target type[NFCI]Erich Keane2017-07-211-0/+82
Targets.cpp is getting unwieldy, and even minor changes cause the entire thing to cause recompilation for everyone. This patch bites the bullet and breaks it up into a number of files. I tended to keep function definitions in the class declaration unless it caused additional includes to be necessary. In those cases, I pulled it over into the .cpp file. Content is copy/paste for the most part, besides includes/format/etc. Differential Revision: https://reviews.llvm.org/D35701 llvm-svn: 308791
OpenPOWER on IntegriCloud