diff options
author | Puranjay Mohan <puranjay12@gmail.com> | 2024-04-04 14:42:02 +0300 |
---|---|---|
committer | Daniel Borkmann <daniel@iogearbox.net> | 2024-04-04 17:48:10 +0300 |
commit | 633a6e01d1a20b24a16899094c249a8cb2aad4b2 (patch) | |
tree | 8dee43335ab942606e838b9e70beb506ec85ace1 /arch/riscv | |
parent | af682b767a41772499f8e54ca7d7e1deb3395f44 (diff) | |
download | linux-633a6e01d1a20b24a16899094c249a8cb2aad4b2.tar.xz |
bpf, riscv: Implement PROBE_MEM32 pseudo instructions
Add support for [LDX | STX | ST], PROBE_MEM32, [B | H | W | DW]
instructions. They are similar to PROBE_MEM instructions with the
following differences:
- PROBE_MEM32 supports store.
- PROBE_MEM32 relies on the verifier to clear upper 32-bit of the
src/dst register
- PROBE_MEM32 adds 64-bit kern_vm_start address (which is stored in S7
in the prologue). Due to bpf_arena constructions such S7 + reg +
off16 access is guaranteed to be within arena virtual range, so no
address check at run-time.
- S11 is a free callee-saved register, so it is used to store kern_vm_start
- PROBE_MEM32 allows STX and ST. If they fault the store is a nop. When
LDX faults the destination register is zeroed.
To support these on riscv, we do tmp = S7 + src/dst reg and then use
tmp2 as the new src/dst register. This allows us to reuse most of the
code for normal [LDX | STX | ST].
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Pu Lehui <pulehui@huawei.com>
Reviewed-by: Pu Lehui <pulehui@huawei.com>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20240404114203.105970-2-puranjay12@gmail.com
Diffstat (limited to 'arch/riscv')
-rw-r--r-- | arch/riscv/net/bpf_jit.h | 1 | ||||
-rw-r--r-- | arch/riscv/net/bpf_jit_comp64.c | 189 | ||||
-rw-r--r-- | arch/riscv/net/bpf_jit_core.c | 1 |
3 files changed, 189 insertions, 2 deletions
diff --git a/arch/riscv/net/bpf_jit.h b/arch/riscv/net/bpf_jit.h index f4b6b3b9edda..8a47da08dd9c 100644 --- a/arch/riscv/net/bpf_jit.h +++ b/arch/riscv/net/bpf_jit.h @@ -81,6 +81,7 @@ struct rv_jit_context { int nexentries; unsigned long flags; int stack_size; + u64 arena_vm_start; }; /* Convert from ninsns to bytes. */ diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index 1adf2f39ce59..a4c8e1e6c1e2 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -18,6 +18,7 @@ #define RV_REG_TCC RV_REG_A6 #define RV_REG_TCC_SAVED RV_REG_S6 /* Store A6 in S6 if program do calls */ +#define RV_REG_ARENA RV_REG_S7 /* For storing arena_vm_start */ static const int regmap[] = { [BPF_REG_0] = RV_REG_A5, @@ -255,6 +256,10 @@ static void __build_epilogue(bool is_tail_call, struct rv_jit_context *ctx) emit_ld(RV_REG_S6, store_offset, RV_REG_SP, ctx); store_offset -= 8; } + if (ctx->arena_vm_start) { + emit_ld(RV_REG_ARENA, store_offset, RV_REG_SP, ctx); + store_offset -= 8; + } emit_addi(RV_REG_SP, RV_REG_SP, stack_adjust, ctx); /* Set return value. */ @@ -548,6 +553,7 @@ static void emit_atomic(u8 rd, u8 rs, s16 off, s32 imm, bool is64, #define BPF_FIXUP_OFFSET_MASK GENMASK(26, 0) #define BPF_FIXUP_REG_MASK GENMASK(31, 27) +#define REG_DONT_CLEAR_MARKER 0 /* RV_REG_ZERO unused in pt_regmap */ bool ex_handler_bpf(const struct exception_table_entry *ex, struct pt_regs *regs) @@ -555,7 +561,8 @@ bool ex_handler_bpf(const struct exception_table_entry *ex, off_t offset = FIELD_GET(BPF_FIXUP_OFFSET_MASK, ex->fixup); int regs_offset = FIELD_GET(BPF_FIXUP_REG_MASK, ex->fixup); - *(unsigned long *)((void *)regs + pt_regmap[regs_offset]) = 0; + if (regs_offset != REG_DONT_CLEAR_MARKER) + *(unsigned long *)((void *)regs + pt_regmap[regs_offset]) = 0; regs->epc = (unsigned long)&ex->fixup - offset; return true; @@ -572,7 +579,8 @@ static int add_exception_handler(const struct bpf_insn *insn, off_t fixup_offset; if (!ctx->insns || !ctx->ro_insns || !ctx->prog->aux->extable || - (BPF_MODE(insn->code) != BPF_PROBE_MEM && BPF_MODE(insn->code) != BPF_PROBE_MEMSX)) + (BPF_MODE(insn->code) != BPF_PROBE_MEM && BPF_MODE(insn->code) != BPF_PROBE_MEMSX && + BPF_MODE(insn->code) != BPF_PROBE_MEM32)) return 0; if (WARN_ON_ONCE(ctx->nexentries >= ctx->prog->aux->num_exentries)) @@ -1539,6 +1547,11 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, case BPF_LDX | BPF_PROBE_MEMSX | BPF_B: case BPF_LDX | BPF_PROBE_MEMSX | BPF_H: case BPF_LDX | BPF_PROBE_MEMSX | BPF_W: + /* LDX | PROBE_MEM32: dst = *(unsigned size *)(src + RV_REG_ARENA + off) */ + case BPF_LDX | BPF_PROBE_MEM32 | BPF_B: + case BPF_LDX | BPF_PROBE_MEM32 | BPF_H: + case BPF_LDX | BPF_PROBE_MEM32 | BPF_W: + case BPF_LDX | BPF_PROBE_MEM32 | BPF_DW: { int insn_len, insns_start; bool sign_ext; @@ -1546,6 +1559,11 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, sign_ext = BPF_MODE(insn->code) == BPF_MEMSX || BPF_MODE(insn->code) == BPF_PROBE_MEMSX; + if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) { + emit_add(RV_REG_T2, rs, RV_REG_ARENA, ctx); + rs = RV_REG_T2; + } + switch (BPF_SIZE(code)) { case BPF_B: if (is_12b_int(off)) { @@ -1682,6 +1700,86 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, emit_sd(RV_REG_T2, 0, RV_REG_T1, ctx); break; + case BPF_ST | BPF_PROBE_MEM32 | BPF_B: + case BPF_ST | BPF_PROBE_MEM32 | BPF_H: + case BPF_ST | BPF_PROBE_MEM32 | BPF_W: + case BPF_ST | BPF_PROBE_MEM32 | BPF_DW: + { + int insn_len, insns_start; + + emit_add(RV_REG_T3, rd, RV_REG_ARENA, ctx); + rd = RV_REG_T3; + + /* Load imm to a register then store it */ + emit_imm(RV_REG_T1, imm, ctx); + + switch (BPF_SIZE(code)) { + case BPF_B: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit(rv_sb(rd, off, RV_REG_T1), ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T2, off, ctx); + emit_add(RV_REG_T2, RV_REG_T2, rd, ctx); + insns_start = ctx->ninsns; + emit(rv_sb(RV_REG_T2, 0, RV_REG_T1), ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_H: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit(rv_sh(rd, off, RV_REG_T1), ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T2, off, ctx); + emit_add(RV_REG_T2, RV_REG_T2, rd, ctx); + insns_start = ctx->ninsns; + emit(rv_sh(RV_REG_T2, 0, RV_REG_T1), ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_W: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit_sw(rd, off, RV_REG_T1, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T2, off, ctx); + emit_add(RV_REG_T2, RV_REG_T2, rd, ctx); + insns_start = ctx->ninsns; + emit_sw(RV_REG_T2, 0, RV_REG_T1, ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_DW: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit_sd(rd, off, RV_REG_T1, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T2, off, ctx); + emit_add(RV_REG_T2, RV_REG_T2, rd, ctx); + insns_start = ctx->ninsns; + emit_sd(RV_REG_T2, 0, RV_REG_T1, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + ret = add_exception_handler(insn, ctx, REG_DONT_CLEAR_MARKER, + insn_len); + if (ret) + return ret; + + break; + } + /* STX: *(size *)(dst + off) = src */ case BPF_STX | BPF_MEM | BPF_B: if (is_12b_int(off)) { @@ -1728,6 +1826,84 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, emit_atomic(rd, rs, off, imm, BPF_SIZE(code) == BPF_DW, ctx); break; + + case BPF_STX | BPF_PROBE_MEM32 | BPF_B: + case BPF_STX | BPF_PROBE_MEM32 | BPF_H: + case BPF_STX | BPF_PROBE_MEM32 | BPF_W: + case BPF_STX | BPF_PROBE_MEM32 | BPF_DW: + { + int insn_len, insns_start; + + emit_add(RV_REG_T2, rd, RV_REG_ARENA, ctx); + rd = RV_REG_T2; + + switch (BPF_SIZE(code)) { + case BPF_B: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit(rv_sb(rd, off, rs), ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T1, off, ctx); + emit_add(RV_REG_T1, RV_REG_T1, rd, ctx); + insns_start = ctx->ninsns; + emit(rv_sb(RV_REG_T1, 0, rs), ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_H: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit(rv_sh(rd, off, rs), ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T1, off, ctx); + emit_add(RV_REG_T1, RV_REG_T1, rd, ctx); + insns_start = ctx->ninsns; + emit(rv_sh(RV_REG_T1, 0, rs), ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_W: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit_sw(rd, off, rs, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T1, off, ctx); + emit_add(RV_REG_T1, RV_REG_T1, rd, ctx); + insns_start = ctx->ninsns; + emit_sw(RV_REG_T1, 0, rs, ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_DW: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit_sd(rd, off, rs, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T1, off, ctx); + emit_add(RV_REG_T1, RV_REG_T1, rd, ctx); + insns_start = ctx->ninsns; + emit_sd(RV_REG_T1, 0, rs, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + ret = add_exception_handler(insn, ctx, REG_DONT_CLEAR_MARKER, + insn_len); + if (ret) + return ret; + + break; + } + default: pr_err("bpf-jit: unknown opcode %02x\n", code); return -EINVAL; @@ -1759,6 +1935,8 @@ void bpf_jit_build_prologue(struct rv_jit_context *ctx, bool is_subprog) stack_adjust += 8; if (seen_reg(RV_REG_S6, ctx)) stack_adjust += 8; + if (ctx->arena_vm_start) + stack_adjust += 8; stack_adjust = round_up(stack_adjust, 16); stack_adjust += bpf_stack_adjust; @@ -1810,6 +1988,10 @@ void bpf_jit_build_prologue(struct rv_jit_context *ctx, bool is_subprog) emit_sd(RV_REG_SP, store_offset, RV_REG_S6, ctx); store_offset -= 8; } + if (ctx->arena_vm_start) { + emit_sd(RV_REG_SP, store_offset, RV_REG_ARENA, ctx); + store_offset -= 8; + } emit_addi(RV_REG_FP, RV_REG_SP, stack_adjust, ctx); @@ -1823,6 +2005,9 @@ void bpf_jit_build_prologue(struct rv_jit_context *ctx, bool is_subprog) emit_mv(RV_REG_TCC_SAVED, RV_REG_TCC, ctx); ctx->stack_size = stack_adjust; + + if (ctx->arena_vm_start) + emit_imm(RV_REG_ARENA, ctx->arena_vm_start, ctx); } void bpf_jit_build_epilogue(struct rv_jit_context *ctx) diff --git a/arch/riscv/net/bpf_jit_core.c b/arch/riscv/net/bpf_jit_core.c index 6b3acac30c06..9ab739b9f9a2 100644 --- a/arch/riscv/net/bpf_jit_core.c +++ b/arch/riscv/net/bpf_jit_core.c @@ -80,6 +80,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) goto skip_init_ctx; } + ctx->arena_vm_start = bpf_arena_get_kern_vm_start(prog->aux->arena); ctx->prog = prog; ctx->offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL); if (!ctx->offset) { |