[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
diff --git a/llvm/lib/Support/Host.cpp b/llvm/lib/Support/Host.cpp
index c81b1f1..1b907bc 100644
--- a/llvm/lib/Support/Host.cpp
+++ b/llvm/lib/Support/Host.cpp
@@ -330,7 +330,19 @@
#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 @@
} 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";