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| author | Jiong Wang <jiwang@tilera.com> | 2019-02-07 10:43:09 +0000 |
|---|---|---|
| committer | Jiong Wang <jiwang@tilera.com> | 2019-02-07 10:43:09 +0000 |
| commit | 66b18e575571da027e31e4db07500835dcefb7f7 (patch) | |
| tree | 0cf37e6b90ac34fbd8cbf9baa57b2a9781c2d40a /llvm/lib/Support/Host.cpp | |
| parent | 638110a20883df1ca86d2046ec5263b5af899bf9 (diff) | |
| download | bcm5719-llvm-66b18e575571da027e31e4db07500835dcefb7f7.tar.gz bcm5719-llvm-66b18e575571da027e31e4db07500835dcefb7f7.zip | |
[BPF] add code-gen support for JMP32 instructions
JMP32 instructions has been added to eBPF ISA. They are 32-bit variants of
existing BPF conditional jump instructions, but the comparison happens on
low 32-bit sub-register only, therefore some unnecessary extensions could
be saved.
JMP32 instructions will only be available for -mcpu=v3. Host probe hook has
been updated accordingly.
JMP32 instructions will only be enabled in code-gen when -mattr=+alu32
enabled, meaning compiling the program using sub-register mode.
For JMP32 encoding, it is a new instruction class, and is using the
reserved eBPF class number 0x6.
This patch has been tested by compiling and running kernel bpf selftests
with JMP32 enabled.
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
llvm-svn: 353384
Diffstat (limited to 'llvm/lib/Support/Host.cpp')
| -rw-r--r-- | llvm/lib/Support/Host.cpp | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/llvm/lib/Support/Host.cpp b/llvm/lib/Support/Host.cpp index c81b1f14647..1b907bc6284 100644 --- a/llvm/lib/Support/Host.cpp +++ b/llvm/lib/Support/Host.cpp @@ -330,7 +330,19 @@ StringRef sys::detail::getHostCPUNameForBPF() { #if !defined(__linux__) || !defined(__x86_64__) return "generic"; #else - uint8_t insns[40] __attribute__ ((aligned (8))) = + uint8_t v3_insns[40] __attribute__ ((aligned (8))) = + /* BPF_MOV64_IMM(BPF_REG_0, 0) */ + { 0xb7, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, + /* BPF_MOV64_IMM(BPF_REG_2, 1) */ + 0xb7, 0x2, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, + /* BPF_JMP32_REG(BPF_JLT, BPF_REG_0, BPF_REG_2, 1) */ + 0xae, 0x20, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, + /* BPF_MOV64_IMM(BPF_REG_0, 1) */ + 0xb7, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, + /* BPF_EXIT_INSN() */ + 0x95, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0 }; + + uint8_t v2_insns[40] __attribute__ ((aligned (8))) = /* BPF_MOV64_IMM(BPF_REG_0, 0) */ { 0xb7, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, /* BPF_MOV64_IMM(BPF_REG_2, 1) */ @@ -355,10 +367,23 @@ StringRef sys::detail::getHostCPUNameForBPF() { } attr = {}; attr.prog_type = 1; /* BPF_PROG_TYPE_SOCKET_FILTER */ attr.insn_cnt = 5; - attr.insns = (uint64_t)insns; + attr.insns = (uint64_t)v3_insns; attr.license = (uint64_t)"DUMMY"; - int fd = syscall(321 /* __NR_bpf */, 5 /* BPF_PROG_LOAD */, &attr, sizeof(attr)); + int fd = syscall(321 /* __NR_bpf */, 5 /* BPF_PROG_LOAD */, &attr, + sizeof(attr)); + if (fd >= 0) { + close(fd); + return "v3"; + } + + /* Clear the whole attr in case its content changed by syscall. */ + memset(&attr, 0, sizeof(attr)); + attr.prog_type = 1; /* BPF_PROG_TYPE_SOCKET_FILTER */ + attr.insn_cnt = 5; + attr.insns = (uint64_t)v2_insns; + attr.license = (uint64_t)"DUMMY"; + fd = syscall(321 /* __NR_bpf */, 5 /* BPF_PROG_LOAD */, &attr, sizeof(attr)); if (fd >= 0) { close(fd); return "v2"; |
