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 _R26 in the prologue). Due to bpf_arena constructions such _R26 + reg + off16 access is guaranteed to be within arena virtual range, so no address check at run-time. - 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 powerpc, we do tmp1 = _R26 + src/dst reg and then use tmp1 as the new src/dst register. This allows us to reuse most of the code for normal [LDX | STX | ST].
Additionally, bpf_jit_emit_probe_mem_store() is introduced to emit instructions for storing memory values depending on the size (byte, halfword, word, doubleword).
Stack layout is adjusted to introduce a new NVR (_R26) and to make BPF_PPC_STACKFRAME quadword aligned (local_tmp_var is increased by 8 bytes).
Signed-off-by: Saket Kumar Bhaskar skb99@linux.ibm.com --- arch/powerpc/net/bpf_jit.h | 5 +- arch/powerpc/net/bpf_jit_comp.c | 10 +- arch/powerpc/net/bpf_jit_comp32.c | 2 +- arch/powerpc/net/bpf_jit_comp64.c | 162 ++++++++++++++++++++++++++---- 4 files changed, 155 insertions(+), 24 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index 4c26912c2e3c..2d095a873305 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -161,9 +161,10 @@ struct codegen_context { unsigned int seen; unsigned int idx; unsigned int stack_size; - int b2p[MAX_BPF_JIT_REG + 2]; + int b2p[MAX_BPF_JIT_REG + 3]; unsigned int exentry_idx; unsigned int alt_exit_addr; + u64 arena_vm_start; };
#define bpf_to_ppc(r) (ctx->b2p[r]) @@ -201,7 +202,7 @@ int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg,
int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass, struct codegen_context *ctx, int insn_idx, - int jmp_off, int dst_reg); + int jmp_off, int dst_reg, u32 code);
#endif
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index c0684733e9d6..7d070232159f 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -204,6 +204,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
/* Make sure that the stack is quadword aligned. */ cgctx.stack_size = round_up(fp->aux->stack_depth, 16); + cgctx.arena_vm_start = bpf_arena_get_kern_vm_start(fp->aux->arena);
/* Scouting faux-generate pass 0 */ if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) { @@ -326,7 +327,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) */ int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass, struct codegen_context *ctx, int insn_idx, int jmp_off, - int dst_reg) + int dst_reg, u32 code) { off_t offset; unsigned long pc; @@ -355,6 +356,9 @@ int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass (ctx->exentry_idx * BPF_FIXUP_LEN * 4);
fixup[0] = PPC_RAW_LI(dst_reg, 0); + if (BPF_CLASS(code) == BPF_ST || BPF_CLASS(code) == BPF_STX) + fixup[0] = PPC_RAW_NOP(); + if (IS_ENABLED(CONFIG_PPC32)) fixup[1] = PPC_RAW_LI(dst_reg - 1, 0); /* clear higher 32-bit register too */
@@ -579,7 +583,7 @@ static void bpf_trampoline_setup_tail_call_cnt(u32 *image, struct codegen_contex { if (IS_ENABLED(CONFIG_PPC64)) { /* See bpf_jit_stack_tailcallcnt() */ - int tailcallcnt_offset = 6 * 8; + int tailcallcnt_offset = 7 * 8;
EMIT(PPC_RAW_LL(_R3, _R1, func_frame_offset - tailcallcnt_offset)); EMIT(PPC_RAW_STL(_R3, _R1, -tailcallcnt_offset)); @@ -594,7 +598,7 @@ static void bpf_trampoline_restore_tail_call_cnt(u32 *image, struct codegen_cont { if (IS_ENABLED(CONFIG_PPC64)) { /* See bpf_jit_stack_tailcallcnt() */ - int tailcallcnt_offset = 6 * 8; + int tailcallcnt_offset = 7 * 8;
EMIT(PPC_RAW_LL(_R3, _R1, -tailcallcnt_offset)); EMIT(PPC_RAW_STL(_R3, _R1, func_frame_offset - tailcallcnt_offset)); diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index 0aace304dfe1..3087e744fb25 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -1087,7 +1087,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code }
ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, insn_idx, - jmp_off, dst_reg); + jmp_off, dst_reg, code); if (ret) return ret; } diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 025524378443..569619f1b31c 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -25,18 +25,18 @@ * with our redzone usage. * * [ prev sp ] <------------- - * [ nv gpr save area ] 5*8 | + * [ nv gpr save area ] 6*8 | * [ tail_call_cnt ] 8 | - * [ local_tmp_var ] 16 | + * [ local_tmp_var ] 24 | * fp (r31) --> [ ebpf stack space ] upto 512 | * [ frame header ] 32/112 | * sp (r1) ---> [ stack pointer ] -------------- */
/* for gpr non volatile registers BPG_REG_6 to 10 */ -#define BPF_PPC_STACK_SAVE (5*8) +#define BPF_PPC_STACK_SAVE (6*8) /* for bpf JIT code internal usage */ -#define BPF_PPC_STACK_LOCALS 24 +#define BPF_PPC_STACK_LOCALS 32 /* stack frame excluding BPF stack, ensure this is quadword aligned */ #define BPF_PPC_STACKFRAME (STACK_FRAME_MIN_SIZE + \ BPF_PPC_STACK_LOCALS + BPF_PPC_STACK_SAVE) @@ -44,6 +44,7 @@ /* BPF register usage */ #define TMP_REG_1 (MAX_BPF_JIT_REG + 0) #define TMP_REG_2 (MAX_BPF_JIT_REG + 1) +#define ARENA_VM_START (MAX_BPF_JIT_REG + 2)
/* BPF to ppc register mappings */ void bpf_jit_init_reg_mapping(struct codegen_context *ctx) @@ -67,10 +68,12 @@ void bpf_jit_init_reg_mapping(struct codegen_context *ctx) ctx->b2p[BPF_REG_AX] = _R12; ctx->b2p[TMP_REG_1] = _R9; ctx->b2p[TMP_REG_2] = _R10; + /* non volatile register for kern_vm_start address */ + ctx->b2p[ARENA_VM_START] = _R26; }
-/* PPC NVR range -- update this if we ever use NVRs below r27 */ -#define BPF_PPC_NVR_MIN _R27 +/* PPC NVR range -- update this if we ever use NVRs below r26 */ +#define BPF_PPC_NVR_MIN _R26
static inline bool bpf_has_stack_frame(struct codegen_context *ctx) { @@ -89,9 +92,9 @@ static inline bool bpf_has_stack_frame(struct codegen_context *ctx) * [ prev sp ] <------------- * [ ... ] | * sp (r1) ---> [ stack pointer ] -------------- - * [ nv gpr save area ] 5*8 + * [ nv gpr save area ] 6*8 * [ tail_call_cnt ] 8 - * [ local_tmp_var ] 16 + * [ local_tmp_var ] 24 * [ unused red zone ] 224 */ static int bpf_jit_stack_local(struct codegen_context *ctx) @@ -99,12 +102,12 @@ static int bpf_jit_stack_local(struct codegen_context *ctx) if (bpf_has_stack_frame(ctx)) return STACK_FRAME_MIN_SIZE + ctx->stack_size; else - return -(BPF_PPC_STACK_SAVE + 24); + return -(BPF_PPC_STACK_SAVE + 32); }
static int bpf_jit_stack_tailcallcnt(struct codegen_context *ctx) { - return bpf_jit_stack_local(ctx) + 16; + return bpf_jit_stack_local(ctx) + 24; }
static int bpf_jit_stack_offsetof(struct codegen_context *ctx, int reg) @@ -170,10 +173,17 @@ void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) if (bpf_is_seen_register(ctx, bpf_to_ppc(i))) EMIT(PPC_RAW_STD(bpf_to_ppc(i), _R1, bpf_jit_stack_offsetof(ctx, bpf_to_ppc(i))));
+ if (ctx->arena_vm_start) + EMIT(PPC_RAW_STD(bpf_to_ppc(ARENA_VM_START), _R1, + bpf_jit_stack_offsetof(ctx, bpf_to_ppc(ARENA_VM_START)))); + /* Setup frame pointer to point to the bpf stack area */ if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_FP))) EMIT(PPC_RAW_ADDI(bpf_to_ppc(BPF_REG_FP), _R1, STACK_FRAME_MIN_SIZE + ctx->stack_size)); + + if (ctx->arena_vm_start) + PPC_LI64(bpf_to_ppc(ARENA_VM_START), ctx->arena_vm_start); }
static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx) @@ -185,6 +195,10 @@ static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx if (bpf_is_seen_register(ctx, bpf_to_ppc(i))) EMIT(PPC_RAW_LD(bpf_to_ppc(i), _R1, bpf_jit_stack_offsetof(ctx, bpf_to_ppc(i))));
+ if (ctx->arena_vm_start) + EMIT(PPC_RAW_LD(bpf_to_ppc(ARENA_VM_START), _R1, + bpf_jit_stack_offsetof(ctx, bpf_to_ppc(ARENA_VM_START)))); + /* Tear down our stack frame */ if (bpf_has_stack_frame(ctx)) { EMIT(PPC_RAW_ADDI(_R1, _R1, BPF_PPC_STACKFRAME + ctx->stack_size)); @@ -396,11 +410,11 @@ void bpf_stf_barrier(void); asm ( " .global bpf_stf_barrier ;" " bpf_stf_barrier: ;" -" std 21,-64(1) ;" -" std 22,-56(1) ;" +" std 21,-80(1) ;" +" std 22,-72(1) ;" " sync ;" -" ld 21,-64(1) ;" -" ld 22,-56(1) ;" +" ld 21,-80(1) ;" +" ld 22,-72(1) ;" " ori 31,31,0 ;" " .rept 14 ;" " b 1f ;" @@ -409,6 +423,36 @@ asm ( " blr ;" );
+static int bpf_jit_emit_probe_mem_store(struct codegen_context *ctx, u32 src_reg, s16 off, + u32 code, u32 *image) +{ + u32 tmp1_reg = bpf_to_ppc(TMP_REG_1); + u32 tmp2_reg = bpf_to_ppc(TMP_REG_2); + + switch (BPF_SIZE(code)) { + case BPF_B: + EMIT(PPC_RAW_STB(src_reg, tmp1_reg, off)); + break; + case BPF_H: + EMIT(PPC_RAW_STH(src_reg, tmp1_reg, off)); + break; + case BPF_W: + EMIT(PPC_RAW_STW(src_reg, tmp1_reg, off)); + break; + case BPF_DW: + if (off % 4) { + EMIT(PPC_RAW_LI(tmp2_reg, off)); + EMIT(PPC_RAW_STDX(src_reg, tmp1_reg, tmp2_reg)); + } else { + EMIT(PPC_RAW_STD(src_reg, tmp1_reg, off)); + } + break; + default: + return -EINVAL; + } + return 0; +} + static int emit_atomic_ld_st(const struct bpf_insn insn, struct codegen_context *ctx, u32 *image) { u32 code = insn.code; @@ -960,6 +1004,50 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code } 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: + + EMIT(PPC_RAW_ADD(tmp1_reg, dst_reg, bpf_to_ppc(ARENA_VM_START))); + + ret = bpf_jit_emit_probe_mem_store(ctx, src_reg, off, code, image); + if (ret) + return ret; + + ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, + ctx->idx - 1, 4, -1, code); + if (ret) + return ret; + + 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: + + EMIT(PPC_RAW_ADD(tmp1_reg, dst_reg, bpf_to_ppc(ARENA_VM_START))); + + if (BPF_SIZE(code) == BPF_W || BPF_SIZE(code) == BPF_DW) { + PPC_LI32(tmp2_reg, imm); + src_reg = tmp2_reg; + } else { + EMIT(PPC_RAW_LI(tmp2_reg, imm)); + src_reg = tmp2_reg; + } + + ret = bpf_jit_emit_probe_mem_store(ctx, src_reg, off, code, image); + if (ret) + return ret; + + ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, + ctx->idx - 1, 4, -1, code); + if (ret) + return ret; + + break; + /* * BPF_STX ATOMIC (atomic ops) */ @@ -1112,9 +1200,10 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code * Check if 'off' is word aligned for BPF_DW, because * we might generate two instructions. */ - if ((BPF_SIZE(code) == BPF_DW || - (BPF_SIZE(code) == BPF_B && BPF_MODE(code) == BPF_PROBE_MEMSX)) && - (off & 3)) + if ((BPF_SIZE(code) == BPF_DW && (off & 3)) || + (BPF_SIZE(code) == BPF_B && + BPF_MODE(code) == BPF_PROBE_MEMSX) || + (BPF_SIZE(code) == BPF_B && BPF_MODE(code) == BPF_MEMSX)) PPC_JMP((ctx->idx + 3) * 4); else PPC_JMP((ctx->idx + 2) * 4); @@ -1160,12 +1249,49 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
if (BPF_MODE(code) == BPF_PROBE_MEM) { ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, - ctx->idx - 1, 4, dst_reg); + ctx->idx - 1, 4, dst_reg, code); if (ret) return ret; } break;
+ /* dst = *(u64 *)(ul) (src + ARENA_VM_START + 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: + + EMIT(PPC_RAW_ADD(tmp1_reg, src_reg, bpf_to_ppc(ARENA_VM_START))); + + switch (size) { + case BPF_B: + EMIT(PPC_RAW_LBZ(dst_reg, tmp1_reg, off)); + break; + case BPF_H: + EMIT(PPC_RAW_LHZ(dst_reg, tmp1_reg, off)); + break; + case BPF_W: + EMIT(PPC_RAW_LWZ(dst_reg, tmp1_reg, off)); + break; + case BPF_DW: + if (off % 4) { + EMIT(PPC_RAW_LI(tmp2_reg, off)); + EMIT(PPC_RAW_LDX(dst_reg, tmp1_reg, tmp2_reg)); + } else { + EMIT(PPC_RAW_LD(dst_reg, tmp1_reg, off)); + } + break; + } + + if (size != BPF_DW && insn_is_zext(&insn[i + 1])) + addrs[++i] = ctx->idx * 4; + + ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, + ctx->idx - 1, 4, dst_reg, code); + if (ret) + return ret; + break; + /* * Doubleword load * 16 byte instruction that uses two 'struct bpf_insn'