diff options
author | Alexei Starovoitov <ast@kernel.org> | 2024-05-13 02:54:34 +0300 |
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committer | Alexei Starovoitov <ast@kernel.org> | 2024-05-13 02:54:35 +0300 |
commit | 55302bc1ca64160fec4dfa25e52142691ecb5dcd (patch) | |
tree | fd23f2dc376d2db2d93c1831ad0abae58eb0868e | |
parent | f122668ddcce450c2585f0be4bf4478d6fd6176b (diff) | |
parent | 75fe4c0b3e181f5e3b990128013ac192fdfd4012 (diff) | |
download | linux-55302bc1ca64160fec4dfa25e52142691ecb5dcd.tar.xz |
Merge branch 'bpf-inline-helpers-in-arm64-and-riscv-jits'
Puranjay Mohan says:
====================
bpf: Inline helpers in arm64 and riscv JITs
Changes in v5 -> v6:
arm64 v5: https://lore.kernel.org/all/20240430234739.79185-1-puranjay@kernel.org/
riscv v2: https://lore.kernel.org/all/20240430175834.33152-1-puranjay@kernel.org/
- Combine riscv and arm64 changes in single series
- Some coding style fixes
Changes in v4 -> v5:
v4: https://lore.kernel.org/all/20240429131647.50165-1-puranjay@kernel.org/
- Implement the inlining of the bpf_get_smp_processor_id() in the JIT.
NOTE: This needs to be based on:
https://lore.kernel.org/all/20240430175834.33152-1-puranjay@kernel.org/
to be built.
Manual run of bpf-ci with this series rebased on above:
https://github.com/kernel-patches/bpf/pull/6929
Changes in v3 -> v4:
v3: https://lore.kernel.org/all/20240426121349.97651-1-puranjay@kernel.org/
- Fix coding style issue related to C89 standards.
Changes in v2 -> v3:
v2: https://lore.kernel.org/all/20240424173550.16359-1-puranjay@kernel.org/
- Fixed the xlated dump of percpu mov to "r0 = &(void __percpu *)(r0)"
- Made ARM64 and x86-64 use the same code for inlining. The only difference
that remains is the per-cpu address of the cpu_number.
Changes in v1 -> v2:
v1: https://lore.kernel.org/all/20240405091707.66675-1-puranjay12@gmail.com/
- Add a patch to inline bpf_get_smp_processor_id()
- Fix an issue in MRS instruction encoding as pointed out by Will
- Remove CONFIG_SMP check because arm64 kernel always compiles with CONFIG_SMP
This series adds the support of internal only per-CPU instructions and inlines
the bpf_get_smp_processor_id() helper call for ARM64 and RISC-V BPF JITs.
Here is an example of calls to bpf_get_smp_processor_id() and
percpu_array_map_lookup_elem() before and after this series on ARM64.
BPF
=====
BEFORE AFTER
-------- -------
int cpu = bpf_get_smp_processor_id(); int cpu = bpf_get_smp_processor_id();
(85) call bpf_get_smp_processor_id#229032 (85) call bpf_get_smp_processor_id#8
p = bpf_map_lookup_elem(map, &zero); p = bpf_map_lookup_elem(map, &zero);
(18) r1 = map[id:78] (18) r1 = map[id:153]
(18) r2 = map[id:82][0]+65536 (18) r2 = map[id:157][0]+65536
(85) call percpu_array_map_lookup_elem#313512 (07) r1 += 496
(61) r0 = *(u32 *)(r2 +0)
(35) if r0 >= 0x1 goto pc+5
(67) r0 <<= 3
(0f) r0 += r1
(79) r0 = *(u64 *)(r0 +0)
(bf) r0 = &(void __percpu *)(r0)
(05) goto pc+1
(b7) r0 = 0
ARM64 JIT
===========
BEFORE AFTER
-------- -------
int cpu = bpf_get_smp_processor_id(); int cpu = bpf_get_smp_processor_id();
mov x10, #0xfffffffffffff4d0 mrs x10, sp_el0
movk x10, #0x802b, lsl #16 ldr w7, [x10, #24]
movk x10, #0x8000, lsl #32
blr x10
add x7, x0, #0x0
p = bpf_map_lookup_elem(map, &zero); p = bpf_map_lookup_elem(map, &zero);
mov x0, #0xffff0003ffffffff mov x0, #0xffff0003ffffffff
movk x0, #0xce5c, lsl #16 movk x0, #0xe0f3, lsl #16
movk x0, #0xca00 movk x0, #0x7c00
mov x1, #0xffff8000ffffffff mov x1, #0xffff8000ffffffff
movk x1, #0x8bdb, lsl #16 movk x1, #0xb0c7, lsl #16
movk x1, #0x6000 movk x1, #0xe000
mov x10, #0xffffffffffff3ed0 add x0, x0, #0x1f0
movk x10, #0x802d, lsl #16 ldr w7, [x1]
movk x10, #0x8000, lsl #32 cmp x7, #0x1
blr x10 b.cs 0x0000000000000090
add x7, x0, #0x0 lsl x7, x7, #3
add x7, x7, x0
ldr x7, [x7]
mrs x10, tpidr_el1
add x7, x7, x10
b 0x0000000000000094
mov x7, #0x0
Performance improvement found using benchmark[1]
./benchs/run_bench_trigger.sh glob-arr-inc arr-inc hash-inc
+---------------+-------------------+-------------------+--------------+
| Name | Before | After | % change |
|---------------+-------------------+-------------------+--------------|
| glob-arr-inc | 23.380 ± 1.675M/s | 25.893 ± 0.026M/s | + 10.74% |
| arr-inc | 23.928 ± 0.034M/s | 25.213 ± 0.063M/s | + 5.37% |
| hash-inc | 12.352 ± 0.005M/s | 12.609 ± 0.013M/s | + 2.08% |
+---------------+-------------------+-------------------+--------------+
[1] https://github.com/anakryiko/linux/commit/8dec900975ef
RISCV64 JIT output for `call bpf_get_smp_processor_id`
=======================================================
Before After
-------- -------
auipc t1,0x848c ld a5,32(tp)
jalr 604(t1)
mv a5,a0
Benchmark using [1] on Qemu.
./benchs/run_bench_trigger.sh glob-arr-inc arr-inc hash-inc
+---------------+------------------+------------------+--------------+
| Name | Before | After | % change |
|---------------+------------------+------------------+--------------|
| glob-arr-inc | 1.077 ± 0.006M/s | 1.336 ± 0.010M/s | + 24.04% |
| arr-inc | 1.078 ± 0.002M/s | 1.332 ± 0.015M/s | + 23.56% |
| hash-inc | 0.494 ± 0.004M/s | 0.653 ± 0.001M/s | + 32.18% |
+---------------+------------------+------------------+--------------+
====================
Link: https://lore.kernel.org/r/20240502151854.9810-1-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
-rw-r--r-- | arch/arm64/include/asm/insn.h | 8 | ||||
-rw-r--r-- | arch/arm64/lib/insn.c | 11 | ||||
-rw-r--r-- | arch/arm64/net/bpf_jit.h | 8 | ||||
-rw-r--r-- | arch/arm64/net/bpf_jit_comp.c | 39 | ||||
-rw-r--r-- | arch/riscv/net/bpf_jit_comp64.c | 50 | ||||
-rw-r--r-- | include/linux/filter.h | 1 | ||||
-rw-r--r-- | kernel/bpf/core.c | 11 | ||||
-rw-r--r-- | kernel/bpf/verifier.c | 4 |
8 files changed, 132 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h index db1aeacd4cd9..8c0a36f72d6f 100644 --- a/arch/arm64/include/asm/insn.h +++ b/arch/arm64/include/asm/insn.h @@ -135,6 +135,12 @@ enum aarch64_insn_special_register { AARCH64_INSN_SPCLREG_SP_EL2 = 0xF210 }; +enum aarch64_insn_system_register { + AARCH64_INSN_SYSREG_TPIDR_EL1 = 0x4684, + AARCH64_INSN_SYSREG_TPIDR_EL2 = 0x6682, + AARCH64_INSN_SYSREG_SP_EL0 = 0x4208, +}; + enum aarch64_insn_variant { AARCH64_INSN_VARIANT_32BIT, AARCH64_INSN_VARIANT_64BIT @@ -686,6 +692,8 @@ u32 aarch64_insn_gen_cas(enum aarch64_insn_register result, } #endif u32 aarch64_insn_gen_dmb(enum aarch64_insn_mb_type type); +u32 aarch64_insn_gen_mrs(enum aarch64_insn_register result, + enum aarch64_insn_system_register sysreg); s32 aarch64_get_branch_offset(u32 insn); u32 aarch64_set_branch_offset(u32 insn, s32 offset); diff --git a/arch/arm64/lib/insn.c b/arch/arm64/lib/insn.c index a635ab83fee3..b008a9b46a7f 100644 --- a/arch/arm64/lib/insn.c +++ b/arch/arm64/lib/insn.c @@ -1515,3 +1515,14 @@ u32 aarch64_insn_gen_dmb(enum aarch64_insn_mb_type type) return insn; } + +u32 aarch64_insn_gen_mrs(enum aarch64_insn_register result, + enum aarch64_insn_system_register sysreg) +{ + u32 insn = aarch64_insn_get_mrs_value(); + + insn &= ~GENMASK(19, 0); + insn |= sysreg << 5; + return aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RT, + insn, result); +} diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h index 23b1b34db088..b22ab2f97a30 100644 --- a/arch/arm64/net/bpf_jit.h +++ b/arch/arm64/net/bpf_jit.h @@ -297,4 +297,12 @@ #define A64_ADR(Rd, offset) \ aarch64_insn_gen_adr(0, offset, Rd, AARCH64_INSN_ADR_TYPE_ADR) +/* MRS */ +#define A64_MRS_TPIDR_EL1(Rt) \ + aarch64_insn_gen_mrs(Rt, AARCH64_INSN_SYSREG_TPIDR_EL1) +#define A64_MRS_TPIDR_EL2(Rt) \ + aarch64_insn_gen_mrs(Rt, AARCH64_INSN_SYSREG_TPIDR_EL2) +#define A64_MRS_SP_EL0(Rt) \ + aarch64_insn_gen_mrs(Rt, AARCH64_INSN_SYSREG_SP_EL0) + #endif /* _BPF_JIT_H */ diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 53347d4217f4..47151414a450 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -890,6 +890,15 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, emit(A64_ORR(1, tmp, dst, tmp), ctx); emit(A64_MOV(1, dst, tmp), ctx); break; + } else if (insn_is_mov_percpu_addr(insn)) { + if (dst != src) + emit(A64_MOV(1, dst, src), ctx); + if (cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN)) + emit(A64_MRS_TPIDR_EL2(tmp), ctx); + else + emit(A64_MRS_TPIDR_EL1(tmp), ctx); + emit(A64_ADD(1, dst, dst, tmp), ctx); + break; } switch (insn->off) { case 0: @@ -1219,6 +1228,21 @@ emit_cond_jmp: const u8 r0 = bpf2a64[BPF_REG_0]; bool func_addr_fixed; u64 func_addr; + u32 cpu_offset; + + /* Implement helper call to bpf_get_smp_processor_id() inline */ + if (insn->src_reg == 0 && insn->imm == BPF_FUNC_get_smp_processor_id) { + cpu_offset = offsetof(struct thread_info, cpu); + + emit(A64_MRS_SP_EL0(tmp), ctx); + if (is_lsi_offset(cpu_offset, 2)) { + emit(A64_LDR32I(r0, tmp, cpu_offset), ctx); + } else { + emit_a64_mov_i(1, tmp2, cpu_offset, ctx); + emit(A64_LDR32(r0, tmp, tmp2), ctx); + } + break; + } ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass, &func_addr, &func_addr_fixed); @@ -2559,6 +2583,21 @@ bool bpf_jit_supports_insn(struct bpf_insn *insn, bool in_arena) return true; } +bool bpf_jit_supports_percpu_insn(void) +{ + return true; +} + +bool bpf_jit_inlines_helper_call(s32 imm) +{ + switch (imm) { + case BPF_FUNC_get_smp_processor_id: + return true; + default: + return false; + } +} + void bpf_jit_free(struct bpf_prog *prog) { if (prog->jited) { diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index 15e482f2c657..a46ec7fb4489 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -12,6 +12,7 @@ #include <linux/stop_machine.h> #include <asm/patch.h> #include <asm/cfi.h> +#include <asm/percpu.h> #include "bpf_jit.h" #define RV_FENTRY_NINSNS 2 @@ -1089,6 +1090,24 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, emit_or(RV_REG_T1, rd, RV_REG_T1, ctx); emit_mv(rd, RV_REG_T1, ctx); break; + } else if (insn_is_mov_percpu_addr(insn)) { + if (rd != rs) + emit_mv(rd, rs, ctx); +#ifdef CONFIG_SMP + /* Load current CPU number in T1 */ + emit_ld(RV_REG_T1, offsetof(struct thread_info, cpu), + RV_REG_TP, ctx); + /* << 3 because offsets are 8 bytes */ + emit_slli(RV_REG_T1, RV_REG_T1, 3, ctx); + /* Load address of __per_cpu_offset array in T2 */ + emit_addr(RV_REG_T2, (u64)&__per_cpu_offset, extra_pass, ctx); + /* Add offset of current CPU to __per_cpu_offset */ + emit_add(RV_REG_T1, RV_REG_T2, RV_REG_T1, ctx); + /* Load __per_cpu_offset[cpu] in T1 */ + emit_ld(RV_REG_T1, 0, RV_REG_T1, ctx); + /* Add the offset to Rd */ + emit_add(rd, rd, RV_REG_T1, ctx); +#endif } if (imm == 1) { /* Special mov32 for zext */ @@ -1474,6 +1493,22 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, bool fixed_addr; u64 addr; + /* Inline calls to bpf_get_smp_processor_id() + * + * RV_REG_TP holds the address of the current CPU's task_struct and thread_info is + * at offset 0 in task_struct. + * Load cpu from thread_info: + * Set R0 to ((struct thread_info *)(RV_REG_TP))->cpu + * + * This replicates the implementation of raw_smp_processor_id() on RISCV + */ + if (insn->src_reg == 0 && insn->imm == BPF_FUNC_get_smp_processor_id) { + /* Load current CPU number in R0 */ + emit_ld(bpf_to_rv_reg(BPF_REG_0, ctx), offsetof(struct thread_info, cpu), + RV_REG_TP, ctx); + break; + } + mark_call(ctx); ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass, &addr, &fixed_addr); @@ -2038,3 +2073,18 @@ bool bpf_jit_supports_arena(void) { return true; } + +bool bpf_jit_supports_percpu_insn(void) +{ + return true; +} + +bool bpf_jit_inlines_helper_call(s32 imm) +{ + switch (imm) { + case BPF_FUNC_get_smp_processor_id: + return true; + default: + return false; + } +} diff --git a/include/linux/filter.h b/include/linux/filter.h index 7a27f19bf44d..3e19bb62ed1a 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -993,6 +993,7 @@ u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5); struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog); void bpf_jit_compile(struct bpf_prog *prog); bool bpf_jit_needs_zext(void); +bool bpf_jit_inlines_helper_call(s32 imm); bool bpf_jit_supports_subprog_tailcalls(void); bool bpf_jit_supports_percpu_insn(void); bool bpf_jit_supports_kfunc_call(void); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 99b8b1c9a248..aa59af9f9bd9 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2941,6 +2941,17 @@ bool __weak bpf_jit_needs_zext(void) return false; } +/* Return true if the JIT inlines the call to the helper corresponding to + * the imm. + * + * The verifier will not patch the insn->imm for the call to the helper if + * this returns true. + */ +bool __weak bpf_jit_inlines_helper_call(s32 imm) +{ + return false; +} + /* Return TRUE if the JIT backend supports mixing bpf2bpf and tailcalls. */ bool __weak bpf_jit_supports_subprog_tailcalls(void) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9e3aba08984e..1658ca4136a3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -19996,6 +19996,10 @@ static int do_misc_fixups(struct bpf_verifier_env *env) goto next_insn; } + /* Skip inlining the helper call if the JIT does it. */ + if (bpf_jit_inlines_helper_call(insn->imm)) + goto next_insn; + if (insn->imm == BPF_FUNC_get_route_realm) prog->dst_needed = 1; if (insn->imm == BPF_FUNC_get_prandom_u32) |