Message ID | 20201207160734.2345502-10-jackmanb@google.com (mailing list archive) |
---|---|
State | Changes Requested |
Delegated to: | BPF |
Headers | show |
Series | Atomics for eBPF | expand |
On 12/7/20 8:07 AM, Brendan Jackman wrote: > This adds instructions for > > atomic[64]_[fetch_]and > atomic[64]_[fetch_]or > atomic[64]_[fetch_]xor > > All these operations are isomorphic enough to implement with the same > verifier, interpreter, and x86 JIT code, hence being a single commit. > > The main interesting thing here is that x86 doesn't directly support > the fetch_ version these operations, so we need to generate a CMPXCHG > loop in the JIT. This requires the use of two temporary registers, > IIUC it's safe to use BPF_REG_AX and x86's AUX_REG for this purpose. > > Signed-off-by: Brendan Jackman <jackmanb@google.com> > --- > arch/x86/net/bpf_jit_comp.c | 50 ++++++++++++++++++++++++++- > include/linux/filter.h | 66 ++++++++++++++++++++++++++++++++++++ > kernel/bpf/core.c | 3 ++ > kernel/bpf/disasm.c | 21 +++++++++--- > kernel/bpf/verifier.c | 6 ++++ > tools/include/linux/filter.h | 66 ++++++++++++++++++++++++++++++++++++ > 6 files changed, 207 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c > index 308241187582..1d4d50199293 100644 > --- a/arch/x86/net/bpf_jit_comp.c > +++ b/arch/x86/net/bpf_jit_comp.c > @@ -808,6 +808,10 @@ static int emit_atomic(u8 **pprog, u8 atomic_op, > /* emit opcode */ > switch (atomic_op) { > case BPF_ADD: > + case BPF_SUB: > + case BPF_AND: > + case BPF_OR: > + case BPF_XOR: > /* lock *(u32/u64*)(dst_reg + off) <op>= src_reg */ > EMIT1(simple_alu_opcodes[atomic_op]); > break; [...] > diff --git a/include/linux/filter.h b/include/linux/filter.h > index e1e1fc946a7c..e100c71555a4 100644 > --- a/include/linux/filter.h > +++ b/include/linux/filter.h > @@ -264,7 +264,13 @@ static inline bool insn_is_zext(const struct bpf_insn *insn) > * Atomic operations: > * > * BPF_ADD *(uint *) (dst_reg + off16) += src_reg > + * BPF_AND *(uint *) (dst_reg + off16) &= src_reg > + * BPF_OR *(uint *) (dst_reg + off16) |= src_reg > + * BPF_XOR *(uint *) (dst_reg + off16) ^= src_reg > * BPF_ADD | BPF_FETCH src_reg = atomic_fetch_add(dst_reg + off16, src_reg); > + * BPF_AND | BPF_FETCH src_reg = atomic_fetch_and(dst_reg + off16, src_reg); > + * BPF_OR | BPF_FETCH src_reg = atomic_fetch_or(dst_reg + off16, src_reg); > + * BPF_XOR | BPF_FETCH src_reg = atomic_fetch_xor(dst_reg + off16, src_reg); > * BPF_XCHG src_reg = atomic_xchg(dst_reg + off16, src_reg) > * BPF_CMPXCHG r0 = atomic_cmpxchg(dst_reg + off16, r0, src_reg) > */ > @@ -295,6 +301,66 @@ static inline bool insn_is_zext(const struct bpf_insn *insn) > .off = OFF, \ > .imm = BPF_ADD }) > > +/* Atomic memory and, *(uint *)(dst_reg + off16) &= src_reg */ > + > +#define BPF_ATOMIC_AND(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_AND }) > + > +/* Atomic memory and with fetch, src_reg = atomic_fetch_and(dst_reg + off, src_reg); */ > + > +#define BPF_ATOMIC_FETCH_AND(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_AND | BPF_FETCH }) > + > +/* Atomic memory or, *(uint *)(dst_reg + off16) |= src_reg */ > + > +#define BPF_ATOMIC_OR(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_OR }) > + > +/* Atomic memory or with fetch, src_reg = atomic_fetch_or(dst_reg + off, src_reg); */ > + > +#define BPF_ATOMIC_FETCH_OR(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_OR | BPF_FETCH }) > + > +/* Atomic memory xor, *(uint *)(dst_reg + off16) ^= src_reg */ > + > +#define BPF_ATOMIC_XOR(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_XOR }) > + > +/* Atomic memory xor with fetch, src_reg = atomic_fetch_xor(dst_reg + off, src_reg); */ > + > +#define BPF_ATOMIC_FETCH_XOR(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_XOR | BPF_FETCH }) Use BPF_ATOMIC macro to define all the above macros? > + > /* Atomic exchange, src_reg = atomic_xchg(dst_reg + off, src_reg) */ > > #define BPF_ATOMIC_XCHG(SIZE, DST, SRC, OFF) \ > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index 1d9e5dcde03a..4b78ff89ec91 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -1642,6 +1642,9 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) > STX_ATOMIC_W: > switch (IMM) { > ATOMIC_ALU_OP(BPF_ADD, add) > + ATOMIC_ALU_OP(BPF_AND, and) > + ATOMIC_ALU_OP(BPF_OR, or) > + ATOMIC_ALU_OP(BPF_XOR, xor) > #undef ATOMIC_ALU_OP > > case BPF_XCHG: [...]
Hi Brendan, I love your patch! Yet something to improve: [auto build test ERROR on 34da87213d3ddd26643aa83deff7ffc6463da0fc] url: https://github.com/0day-ci/linux/commits/Brendan-Jackman/Atomics-for-eBPF/20201208-001343 base: 34da87213d3ddd26643aa83deff7ffc6463da0fc config: m68k-randconfig-r022-20201209 (attached as .config) compiler: m68k-linux-gcc (GCC) 9.3.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://github.com/0day-ci/linux/commit/2a65bda50b756e76e985b1d2bba80b3023a9cdc3 git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Brendan-Jackman/Atomics-for-eBPF/20201208-001343 git checkout 2a65bda50b756e76e985b1d2bba80b3023a9cdc3 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=m68k If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@intel.com> All errors (new ones prefixed by >>): kernel/bpf/core.c:1350:12: warning: no previous prototype for 'bpf_probe_read_kernel' [-Wmissing-prototypes] 1350 | u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr) | ^~~~~~~~~~~~~~~~~~~~~ In file included from kernel/bpf/core.c:21: kernel/bpf/core.c: In function '___bpf_prog_run': include/linux/filter.h:1000:3: warning: cast between incompatible function types from 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} to 'u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, const struct bpf_insn *)'} [-Wcast-function-type] 1000 | ((u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)) \ | ^ kernel/bpf/core.c:1518:13: note: in expansion of macro '__bpf_call_base_args' 1518 | BPF_R0 = (__bpf_call_base_args + insn->imm)(BPF_R1, BPF_R2, | ^~~~~~~~~~~~~~~~~~~~ kernel/bpf/core.c:1638:6: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 1638 | (atomic64_t *)(s64) (DST + insn->off)); \ | ^ kernel/bpf/core.c:1644:3: note: in expansion of macro 'ATOMIC_ALU_OP' 1644 | ATOMIC_ALU_OP(BPF_ADD, add) | ^~~~~~~~~~~~~ kernel/bpf/core.c:1638:6: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 1638 | (atomic64_t *)(s64) (DST + insn->off)); \ | ^ kernel/bpf/core.c:1645:3: note: in expansion of macro 'ATOMIC_ALU_OP' 1645 | ATOMIC_ALU_OP(BPF_AND, and) | ^~~~~~~~~~~~~ kernel/bpf/core.c:1638:6: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 1638 | (atomic64_t *)(s64) (DST + insn->off)); \ | ^ kernel/bpf/core.c:1646:3: note: in expansion of macro 'ATOMIC_ALU_OP' 1646 | ATOMIC_ALU_OP(BPF_OR, or) | ^~~~~~~~~~~~~ kernel/bpf/core.c:1638:6: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 1638 | (atomic64_t *)(s64) (DST + insn->off)); \ | ^ kernel/bpf/core.c:1647:3: note: in expansion of macro 'ATOMIC_ALU_OP' 1647 | ATOMIC_ALU_OP(BPF_XOR, xor) | ^~~~~~~~~~~~~ kernel/bpf/core.c:1657:6: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 1657 | (atomic64_t *)(u64) (DST + insn->off), | ^ kernel/bpf/core.c:1667:6: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 1667 | (atomic64_t *)(u64) (DST + insn->off), | ^ In file included from kernel/bpf/core.c:21: kernel/bpf/core.c: In function 'bpf_patch_call_args': include/linux/filter.h:1000:3: warning: cast between incompatible function types from 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} to 'u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, const struct bpf_insn *)'} [-Wcast-function-type] 1000 | ((u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)) \ | ^ kernel/bpf/core.c:1756:3: note: in expansion of macro '__bpf_call_base_args' 1756 | __bpf_call_base_args; | ^~~~~~~~~~~~~~~~~~~~ {standard input}: Assembler messages: >> {standard input}:3068: Error: operands mismatch -- statement `orl %a1,%d0' ignored {standard input}:3068: Error: invalid instruction for this architecture; needs 68020 or higher (68020 [68k, 68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060]) -- statement `casl %d4,%d0,(%a6)' ignored {standard input}:3116: Error: invalid instruction for this architecture; needs 68020 or higher (68020 [68k, 68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060]) -- statement `casl %d1,%d5,(%a6,%d0.l)' ignored {standard input}:3163: Error: invalid instruction for this architecture; needs 68020 or higher (68020 [68k, 68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060]) -- statement `casl %d4,%d0,(%a6)' ignored >> {standard input}:3225: Error: operands mismatch -- statement `andl %a1,%d0' ignored {standard input}:3225: Error: invalid instruction for this architecture; needs 68020 or higher (68020 [68k, 68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060]) -- statement `casl %d4,%d0,(%a6)' ignored >> {standard input}:3290: Error: operands mismatch -- statement `eorl %a1,%d0' ignored {standard input}:3290: Error: invalid instruction for this architecture; needs 68020 or higher (68020 [68k, 68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060]) -- statement `casl %d4,%d0,(%a6)' ignored {standard input}:3316: Error: invalid instruction for this architecture; needs 68020 or higher (68020 [68k, 68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060]) -- statement `casl %d0,%d5,(%a0)' ignored --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 308241187582..1d4d50199293 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -808,6 +808,10 @@ static int emit_atomic(u8 **pprog, u8 atomic_op, /* emit opcode */ switch (atomic_op) { case BPF_ADD: + case BPF_SUB: + case BPF_AND: + case BPF_OR: + case BPF_XOR: /* lock *(u32/u64*)(dst_reg + off) <op>= src_reg */ EMIT1(simple_alu_opcodes[atomic_op]); break; @@ -1292,8 +1296,52 @@ st: if (is_imm8(insn->off)) case BPF_STX | BPF_ATOMIC | BPF_W: case BPF_STX | BPF_ATOMIC | BPF_DW: + if (insn->imm == (BPF_AND | BPF_FETCH) || + insn->imm == (BPF_OR | BPF_FETCH) || + insn->imm == (BPF_XOR | BPF_FETCH)) { + u8 *branch_target; + bool is64 = BPF_SIZE(insn->code) == BPF_DW; + + /* + * Can't be implemented with a single x86 insn. + * Need to do a CMPXCHG loop. + */ + + /* Will need RAX as a CMPXCHG operand so save R0 */ + emit_mov_reg(&prog, true, BPF_REG_AX, BPF_REG_0); + branch_target = prog; + /* Load old value */ + emit_ldx(&prog, BPF_SIZE(insn->code), + BPF_REG_0, dst_reg, insn->off); + /* + * Perform the (commutative) operation locally, + * put the result in the AUX_REG. + */ + emit_mov_reg(&prog, is64, AUX_REG, BPF_REG_0); + maybe_emit_mod(&prog, AUX_REG, src_reg, is64); + EMIT2(simple_alu_opcodes[BPF_OP(insn->imm)], + add_2reg(0xC0, AUX_REG, src_reg)); + /* Attempt to swap in new value */ + err = emit_atomic(&prog, BPF_CMPXCHG, + dst_reg, AUX_REG, insn->off, + BPF_SIZE(insn->code)); + if (WARN_ON(err)) + return err; + /* + * ZF tells us whether we won the race. If it's + * cleared we need to try again. + */ + EMIT2(X86_JNE, -(prog - branch_target) - 2); + /* Return the pre-modification value */ + emit_mov_reg(&prog, is64, src_reg, BPF_REG_0); + /* Restore R0 after clobbering RAX */ + emit_mov_reg(&prog, true, BPF_REG_0, BPF_REG_AX); + break; + + } + err = emit_atomic(&prog, insn->imm, dst_reg, src_reg, - insn->off, BPF_SIZE(insn->code)); + insn->off, BPF_SIZE(insn->code)); if (err) return err; break; diff --git a/include/linux/filter.h b/include/linux/filter.h index e1e1fc946a7c..e100c71555a4 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -264,7 +264,13 @@ static inline bool insn_is_zext(const struct bpf_insn *insn) * Atomic operations: * * BPF_ADD *(uint *) (dst_reg + off16) += src_reg + * BPF_AND *(uint *) (dst_reg + off16) &= src_reg + * BPF_OR *(uint *) (dst_reg + off16) |= src_reg + * BPF_XOR *(uint *) (dst_reg + off16) ^= src_reg * BPF_ADD | BPF_FETCH src_reg = atomic_fetch_add(dst_reg + off16, src_reg); + * BPF_AND | BPF_FETCH src_reg = atomic_fetch_and(dst_reg + off16, src_reg); + * BPF_OR | BPF_FETCH src_reg = atomic_fetch_or(dst_reg + off16, src_reg); + * BPF_XOR | BPF_FETCH src_reg = atomic_fetch_xor(dst_reg + off16, src_reg); * BPF_XCHG src_reg = atomic_xchg(dst_reg + off16, src_reg) * BPF_CMPXCHG r0 = atomic_cmpxchg(dst_reg + off16, r0, src_reg) */ @@ -295,6 +301,66 @@ static inline bool insn_is_zext(const struct bpf_insn *insn) .off = OFF, \ .imm = BPF_ADD }) +/* Atomic memory and, *(uint *)(dst_reg + off16) &= src_reg */ + +#define BPF_ATOMIC_AND(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_AND }) + +/* Atomic memory and with fetch, src_reg = atomic_fetch_and(dst_reg + off, src_reg); */ + +#define BPF_ATOMIC_FETCH_AND(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_AND | BPF_FETCH }) + +/* Atomic memory or, *(uint *)(dst_reg + off16) |= src_reg */ + +#define BPF_ATOMIC_OR(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_OR }) + +/* Atomic memory or with fetch, src_reg = atomic_fetch_or(dst_reg + off, src_reg); */ + +#define BPF_ATOMIC_FETCH_OR(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_OR | BPF_FETCH }) + +/* Atomic memory xor, *(uint *)(dst_reg + off16) ^= src_reg */ + +#define BPF_ATOMIC_XOR(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_XOR }) + +/* Atomic memory xor with fetch, src_reg = atomic_fetch_xor(dst_reg + off, src_reg); */ + +#define BPF_ATOMIC_FETCH_XOR(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_XOR | BPF_FETCH }) + /* Atomic exchange, src_reg = atomic_xchg(dst_reg + off, src_reg) */ #define BPF_ATOMIC_XCHG(SIZE, DST, SRC, OFF) \ diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 1d9e5dcde03a..4b78ff89ec91 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1642,6 +1642,9 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) STX_ATOMIC_W: switch (IMM) { ATOMIC_ALU_OP(BPF_ADD, add) + ATOMIC_ALU_OP(BPF_AND, and) + ATOMIC_ALU_OP(BPF_OR, or) + ATOMIC_ALU_OP(BPF_XOR, xor) #undef ATOMIC_ALU_OP case BPF_XCHG: diff --git a/kernel/bpf/disasm.c b/kernel/bpf/disasm.c index ee8d1132767b..19ff8fed7f4b 100644 --- a/kernel/bpf/disasm.c +++ b/kernel/bpf/disasm.c @@ -80,6 +80,13 @@ const char *const bpf_alu_string[16] = { [BPF_END >> 4] = "endian", }; +static const char *const bpf_atomic_alu_string[16] = { + [BPF_ADD >> 4] = "add", + [BPF_AND >> 4] = "and", + [BPF_OR >> 4] = "or", + [BPF_XOR >> 4] = "or", +}; + static const char *const bpf_ldst_string[] = { [BPF_W >> 3] = "u32", [BPF_H >> 3] = "u16", @@ -154,17 +161,23 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs, insn->dst_reg, insn->off, insn->src_reg); else if (BPF_MODE(insn->code) == BPF_ATOMIC && - insn->imm == BPF_ADD) { - verbose(cbs->private_data, "(%02x) lock *(%s *)(r%d %+d) += r%d\n", + (insn->imm == BPF_ADD || insn->imm == BPF_ADD || + insn->imm == BPF_OR || insn->imm == BPF_XOR)) { + verbose(cbs->private_data, "(%02x) lock *(%s *)(r%d %+d) %s r%d\n", insn->code, bpf_ldst_string[BPF_SIZE(insn->code) >> 3], insn->dst_reg, insn->off, + bpf_alu_string[BPF_OP(insn->imm) >> 4], insn->src_reg); } else if (BPF_MODE(insn->code) == BPF_ATOMIC && - insn->imm == (BPF_ADD | BPF_FETCH)) { - verbose(cbs->private_data, "(%02x) r%d = atomic%s_fetch_add((%s *)(r%d %+d), r%d)\n", + (insn->imm == (BPF_ADD | BPF_FETCH) || + insn->imm == (BPF_AND | BPF_FETCH) || + insn->imm == (BPF_OR | BPF_FETCH) || + insn->imm == (BPF_XOR | BPF_FETCH))) { + verbose(cbs->private_data, "(%02x) r%d = atomic%s_fetch_%s((%s *)(r%d %+d), r%d)\n", insn->code, insn->src_reg, BPF_SIZE(insn->code) == BPF_DW ? "64" : "", + bpf_atomic_alu_string[BPF_OP(insn->imm) >> 4], bpf_ldst_string[BPF_SIZE(insn->code) >> 3], insn->dst_reg, insn->off, insn->src_reg); } else if (BPF_MODE(insn->code) == BPF_ATOMIC && diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f5f4460b3e4e..ec5265e6d91b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3614,6 +3614,12 @@ static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_i switch (insn->imm) { case BPF_ADD: case BPF_ADD | BPF_FETCH: + case BPF_AND: + case BPF_AND | BPF_FETCH: + case BPF_OR: + case BPF_OR | BPF_FETCH: + case BPF_XOR: + case BPF_XOR | BPF_FETCH: case BPF_XCHG: case BPF_CMPXCHG: break; diff --git a/tools/include/linux/filter.h b/tools/include/linux/filter.h index 21598053fd40..723c7a485e67 100644 --- a/tools/include/linux/filter.h +++ b/tools/include/linux/filter.h @@ -173,7 +173,13 @@ * Atomic operations: * * BPF_ADD *(uint *) (dst_reg + off16) += src_reg + * BPF_AND *(uint *) (dst_reg + off16) &= src_reg + * BPF_OR *(uint *) (dst_reg + off16) |= src_reg + * BPF_XOR *(uint *) (dst_reg + off16) ^= src_reg * BPF_ADD | BPF_FETCH src_reg = atomic_fetch_add(dst_reg + off16, src_reg); + * BPF_AND | BPF_FETCH src_reg = atomic_fetch_and(dst_reg + off16, src_reg); + * BPF_OR | BPF_FETCH src_reg = atomic_fetch_or(dst_reg + off16, src_reg); + * BPF_XOR | BPF_FETCH src_reg = atomic_fetch_xor(dst_reg + off16, src_reg); * BPF_XCHG src_reg = atomic_xchg(dst_reg + off16, src_reg) * BPF_CMPXCHG r0 = atomic_cmpxchg(dst_reg + off16, r0, src_reg) */ @@ -214,6 +220,66 @@ .off = OFF, \ .imm = BPF_ADD | BPF_FETCH }) +/* Atomic memory and, *(uint *)(dst_reg + off16) -= src_reg */ + +#define BPF_ATOMIC_AND(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_AND }) + +/* Atomic memory and with fetch, src_reg = atomic_fetch_and(dst_reg + off, src_reg); */ + +#define BPF_ATOMIC_FETCH_AND(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_AND | BPF_FETCH }) + +/* Atomic memory or, *(uint *)(dst_reg + off16) -= src_reg */ + +#define BPF_ATOMIC_OR(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_OR }) + +/* Atomic memory or with fetch, src_reg = atomic_fetch_or(dst_reg + off, src_reg); */ + +#define BPF_ATOMIC_FETCH_OR(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_OR | BPF_FETCH }) + +/* Atomic memory xor, *(uint *)(dst_reg + off16) -= src_reg */ + +#define BPF_ATOMIC_XOR(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_XOR }) + +/* Atomic memory xor with fetch, src_reg = atomic_fetch_xor(dst_reg + off, src_reg); */ + +#define BPF_ATOMIC_FETCH_XOR(SIZE, DST, SRC, OFF) \ + ((struct bpf_insn) { \ + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ + .dst_reg = DST, \ + .src_reg = SRC, \ + .off = OFF, \ + .imm = BPF_XOR | BPF_FETCH }) + /* Atomic exchange, src_reg = atomic_xchg(dst_reg + off, src_reg) */ #define BPF_ATOMIC_XCHG(SIZE, DST, SRC, OFF) \
This adds instructions for atomic[64]_[fetch_]and atomic[64]_[fetch_]or atomic[64]_[fetch_]xor All these operations are isomorphic enough to implement with the same verifier, interpreter, and x86 JIT code, hence being a single commit. The main interesting thing here is that x86 doesn't directly support the fetch_ version these operations, so we need to generate a CMPXCHG loop in the JIT. This requires the use of two temporary registers, IIUC it's safe to use BPF_REG_AX and x86's AUX_REG for this purpose. Signed-off-by: Brendan Jackman <jackmanb@google.com> --- arch/x86/net/bpf_jit_comp.c | 50 ++++++++++++++++++++++++++- include/linux/filter.h | 66 ++++++++++++++++++++++++++++++++++++ kernel/bpf/core.c | 3 ++ kernel/bpf/disasm.c | 21 +++++++++--- kernel/bpf/verifier.c | 6 ++++ tools/include/linux/filter.h | 66 ++++++++++++++++++++++++++++++++++++ 6 files changed, 207 insertions(+), 5 deletions(-)