From: Eduard Zingerman <eddyz87@gmail.com>
To: Andrii Nakryiko <andrii@kernel.org>,
bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
martin.lau@kernel.org
Cc: kernel-team@meta.com
Subject: Re: [PATCH v5 bpf-next 15/23] bpf: unify 32-bit and 64-bit is_branch_taken logic
Date: Tue, 31 Oct 2023 19:35:50 +0200 [thread overview]
Message-ID: <858e9646b67cb3676a8fdc6f37af5526b26a57aa.camel@gmail.com> (raw)
In-Reply-To: <20231027181346.4019398-16-andrii@kernel.org>
On Fri, 2023-10-27 at 11:13 -0700, Andrii Nakryiko wrote:
> Combine 32-bit and 64-bit is_branch_taken logic for SCALAR_VALUE
> registers. It makes it easier to see parallels between two domains
> (32-bit and 64-bit), and makes subsequent refactoring more
> straightforward.
>
> No functional changes.
>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
> ---
> kernel/bpf/verifier.c | 154 ++++++++++--------------------------------
> 1 file changed, 36 insertions(+), 118 deletions(-)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index fedd6d0e76e5..b911d1111fad 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -14185,166 +14185,86 @@ static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32)
> /*
> * <reg1> <op> <reg2>, currently assuming reg2 is a constant
> */
> -static int is_branch32_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode)
> +static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
> + u8 opcode, bool is_jmp32)
> {
> - struct tnum subreg = tnum_subreg(reg1->var_off);
> - u32 val = (u32)tnum_subreg(reg2->var_off).value;
> - s32 sval = (s32)val;
> + struct tnum t1 = is_jmp32 ? tnum_subreg(reg1->var_off) : reg1->var_off;
> + u64 umin1 = is_jmp32 ? (u64)reg1->u32_min_value : reg1->umin_value;
> + u64 umax1 = is_jmp32 ? (u64)reg1->u32_max_value : reg1->umax_value;
> + s64 smin1 = is_jmp32 ? (s64)reg1->s32_min_value : reg1->smin_value;
> + s64 smax1 = is_jmp32 ? (s64)reg1->s32_max_value : reg1->smax_value;
> + u64 val = is_jmp32 ? (u32)tnum_subreg(reg2->var_off).value : reg2->var_off.value;
> + s64 sval = is_jmp32 ? (s32)val : (s64)val;
>
> switch (opcode) {
> case BPF_JEQ:
> - if (tnum_is_const(subreg))
> - return !!tnum_equals_const(subreg, val);
> - else if (val < reg1->u32_min_value || val > reg1->u32_max_value)
> + if (tnum_is_const(t1))
> + return !!tnum_equals_const(t1, val);
> + else if (val < umin1 || val > umax1)
> return 0;
> - else if (sval < reg1->s32_min_value || sval > reg1->s32_max_value)
> + else if (sval < smin1 || sval > smax1)
> return 0;
> break;
> case BPF_JNE:
> - if (tnum_is_const(subreg))
> - return !tnum_equals_const(subreg, val);
> - else if (val < reg1->u32_min_value || val > reg1->u32_max_value)
> + if (tnum_is_const(t1))
> + return !tnum_equals_const(t1, val);
> + else if (val < umin1 || val > umax1)
> return 1;
> - else if (sval < reg1->s32_min_value || sval > reg1->s32_max_value)
> + else if (sval < smin1 || sval > smax1)
> return 1;
> break;
> case BPF_JSET:
> - if ((~subreg.mask & subreg.value) & val)
> + if ((~t1.mask & t1.value) & val)
> return 1;
> - if (!((subreg.mask | subreg.value) & val))
> + if (!((t1.mask | t1.value) & val))
> return 0;
> break;
> case BPF_JGT:
> - if (reg1->u32_min_value > val)
> + if (umin1 > val )
> return 1;
> - else if (reg1->u32_max_value <= val)
> + else if (umax1 <= val)
> return 0;
> break;
> case BPF_JSGT:
> - if (reg1->s32_min_value > sval)
> + if (smin1 > sval)
> return 1;
> - else if (reg1->s32_max_value <= sval)
> + else if (smax1 <= sval)
> return 0;
> break;
> case BPF_JLT:
> - if (reg1->u32_max_value < val)
> + if (umax1 < val)
> return 1;
> - else if (reg1->u32_min_value >= val)
> + else if (umin1 >= val)
> return 0;
> break;
> case BPF_JSLT:
> - if (reg1->s32_max_value < sval)
> + if (smax1 < sval)
> return 1;
> - else if (reg1->s32_min_value >= sval)
> + else if (smin1 >= sval)
> return 0;
> break;
> case BPF_JGE:
> - if (reg1->u32_min_value >= val)
> + if (umin1 >= val)
> return 1;
> - else if (reg1->u32_max_value < val)
> + else if (umax1 < val)
> return 0;
> break;
> case BPF_JSGE:
> - if (reg1->s32_min_value >= sval)
> + if (smin1 >= sval)
> return 1;
> - else if (reg1->s32_max_value < sval)
> + else if (smax1 < sval)
> return 0;
> break;
> case BPF_JLE:
> - if (reg1->u32_max_value <= val)
> + if (umax1 <= val)
> return 1;
> - else if (reg1->u32_min_value > val)
> + else if (umin1 > val)
> return 0;
> break;
> case BPF_JSLE:
> - if (reg1->s32_max_value <= sval)
> + if (smax1 <= sval)
> return 1;
> - else if (reg1->s32_min_value > sval)
> - return 0;
> - break;
> - }
> -
> - return -1;
> -}
> -
> -
> -/*
> - * <reg1> <op> <reg2>, currently assuming reg2 is a constant
> - */
> -static int is_branch64_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode)
> -{
> - u64 val = reg2->var_off.value;
> - s64 sval = (s64)val;
> -
> - switch (opcode) {
> - case BPF_JEQ:
> - if (tnum_is_const(reg1->var_off))
> - return !!tnum_equals_const(reg1->var_off, val);
> - else if (val < reg1->umin_value || val > reg1->umax_value)
> - return 0;
> - else if (sval < reg1->smin_value || sval > reg1->smax_value)
> - return 0;
> - break;
> - case BPF_JNE:
> - if (tnum_is_const(reg1->var_off))
> - return !tnum_equals_const(reg1->var_off, val);
> - else if (val < reg1->umin_value || val > reg1->umax_value)
> - return 1;
> - else if (sval < reg1->smin_value || sval > reg1->smax_value)
> - return 1;
> - break;
> - case BPF_JSET:
> - if ((~reg1->var_off.mask & reg1->var_off.value) & val)
> - return 1;
> - if (!((reg1->var_off.mask | reg1->var_off.value) & val))
> - return 0;
> - break;
> - case BPF_JGT:
> - if (reg1->umin_value > val)
> - return 1;
> - else if (reg1->umax_value <= val)
> - return 0;
> - break;
> - case BPF_JSGT:
> - if (reg1->smin_value > sval)
> - return 1;
> - else if (reg1->smax_value <= sval)
> - return 0;
> - break;
> - case BPF_JLT:
> - if (reg1->umax_value < val)
> - return 1;
> - else if (reg1->umin_value >= val)
> - return 0;
> - break;
> - case BPF_JSLT:
> - if (reg1->smax_value < sval)
> - return 1;
> - else if (reg1->smin_value >= sval)
> - return 0;
> - break;
> - case BPF_JGE:
> - if (reg1->umin_value >= val)
> - return 1;
> - else if (reg1->umax_value < val)
> - return 0;
> - break;
> - case BPF_JSGE:
> - if (reg1->smin_value >= sval)
> - return 1;
> - else if (reg1->smax_value < sval)
> - return 0;
> - break;
> - case BPF_JLE:
> - if (reg1->umax_value <= val)
> - return 1;
> - else if (reg1->umin_value > val)
> - return 0;
> - break;
> - case BPF_JSLE:
> - if (reg1->smax_value <= sval)
> - return 1;
> - else if (reg1->smin_value > sval)
> + else if (smin1 > sval)
> return 0;
> break;
> }
> @@ -14458,9 +14378,7 @@ static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg
> }
> }
>
> - if (is_jmp32)
> - return is_branch32_taken(reg1, reg2, opcode);
> - return is_branch64_taken(reg1, reg2, opcode);
> + return is_scalar_branch_taken(reg1, reg2, opcode, is_jmp32);
> }
>
> /* Adjusts the register min/max values in the case that the dst_reg is the
next prev parent reply other threads:[~2023-10-31 17:36 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-27 18:13 [PATCH v5 bpf-next 00/23] BPF register bounds logic and testing improvements Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 01/23] selftests/bpf: fix RELEASE=1 build for tc_opts Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 02/23] selftests/bpf: satisfy compiler by having explicit return in btf test Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 03/23] bpf: derive smin/smax from umin/max bounds Andrii Nakryiko
2023-10-31 15:37 ` Eduard Zingerman
2023-10-31 17:30 ` Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 04/23] bpf: derive smin32/smax32 from umin32/umax32 bounds Andrii Nakryiko
2023-10-31 15:37 ` Eduard Zingerman
2023-10-27 18:13 ` [PATCH v5 bpf-next 05/23] bpf: derive subreg bounds from full bounds when upper 32 bits are constant Andrii Nakryiko
2023-10-31 15:37 ` Eduard Zingerman
2023-10-27 18:13 ` [PATCH v5 bpf-next 06/23] bpf: add special smin32/smax32 derivation from 64-bit bounds Andrii Nakryiko
2023-10-31 15:37 ` Eduard Zingerman
2023-10-31 17:39 ` Andrii Nakryiko
2023-10-31 18:41 ` Alexei Starovoitov
2023-10-31 18:49 ` Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 07/23] bpf: improve deduction of 64-bit bounds from 32-bit bounds Andrii Nakryiko
2023-10-31 15:37 ` Eduard Zingerman
2023-10-31 20:26 ` Alexei Starovoitov
2023-10-31 20:33 ` Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 08/23] bpf: try harder to deduce register bounds from different numeric domains Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 09/23] bpf: drop knowledge-losing __reg_combine_{32,64}_into_{64,32} logic Andrii Nakryiko
2023-10-31 15:38 ` Eduard Zingerman
2023-10-27 18:13 ` [PATCH v5 bpf-next 10/23] selftests/bpf: BPF register range bounds tester Andrii Nakryiko
2023-11-08 22:08 ` Eduard Zingerman
2023-11-08 23:23 ` Andrii Nakryiko
2023-11-09 0:30 ` Eduard Zingerman
2023-10-27 18:13 ` [PATCH v5 bpf-next 11/23] bpf: rename is_branch_taken reg arguments to prepare for the second one Andrii Nakryiko
2023-10-30 19:39 ` Alexei Starovoitov
2023-10-31 5:19 ` Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 12/23] bpf: generalize is_branch_taken() to work with two registers Andrii Nakryiko
2023-10-31 15:38 ` Eduard Zingerman
2023-10-31 17:41 ` Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 13/23] bpf: move is_branch_taken() down Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 14/23] bpf: generalize is_branch_taken to handle all conditional jumps in one place Andrii Nakryiko
2023-10-31 15:38 ` Eduard Zingerman
2023-10-27 18:13 ` [PATCH v5 bpf-next 15/23] bpf: unify 32-bit and 64-bit is_branch_taken logic Andrii Nakryiko
2023-10-30 19:52 ` Alexei Starovoitov
2023-10-31 5:28 ` Andrii Nakryiko
2023-10-31 17:35 ` Eduard Zingerman [this message]
2023-10-27 18:13 ` [PATCH v5 bpf-next 16/23] bpf: prepare reg_set_min_max for second set of registers Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 17/23] bpf: generalize reg_set_min_max() to handle two sets of two registers Andrii Nakryiko
2023-10-31 2:02 ` Alexei Starovoitov
2023-10-31 6:03 ` Andrii Nakryiko
2023-10-31 16:23 ` Alexei Starovoitov
2023-10-31 17:50 ` Andrii Nakryiko
2023-10-31 17:56 ` Andrii Nakryiko
2023-10-31 18:04 ` Alexei Starovoitov
2023-10-31 18:06 ` Andrii Nakryiko
2023-10-31 18:14 ` Eduard Zingerman
2023-10-27 18:13 ` [PATCH v5 bpf-next 18/23] bpf: generalize reg_set_min_max() to handle non-const register comparisons Andrii Nakryiko
2023-10-31 23:25 ` Eduard Zingerman
2023-11-01 16:35 ` Andrii Nakryiko
2023-11-01 17:12 ` Eduard Zingerman
2023-10-27 18:13 ` [PATCH v5 bpf-next 19/23] bpf: generalize is_scalar_branch_taken() logic Andrii Nakryiko
2023-10-31 2:12 ` Alexei Starovoitov
2023-10-31 6:12 ` Andrii Nakryiko
2023-10-31 16:34 ` Alexei Starovoitov
2023-10-31 18:01 ` Andrii Nakryiko
2023-10-31 20:53 ` Andrii Nakryiko
2023-10-31 20:55 ` Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 20/23] bpf: enhance BPF_JEQ/BPF_JNE is_branch_taken logic Andrii Nakryiko
2023-10-31 2:20 ` Alexei Starovoitov
2023-10-31 6:16 ` Andrii Nakryiko
2023-10-31 16:36 ` Alexei Starovoitov
2023-10-31 18:04 ` Andrii Nakryiko
2023-10-31 18:06 ` Alexei Starovoitov
2023-10-27 18:13 ` [PATCH v5 bpf-next 21/23] selftests/bpf: adjust OP_EQ/OP_NE handling to use subranges for branch taken Andrii Nakryiko
2023-11-08 18:22 ` Eduard Zingerman
2023-11-08 19:59 ` Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 22/23] selftests/bpf: add range x range test to reg_bounds Andrii Nakryiko
2023-10-27 18:13 ` [PATCH v5 bpf-next 23/23] selftests/bpf: add iter test requiring range x range logic Andrii Nakryiko
2023-10-30 17:55 ` [PATCH v5 bpf-next 00/23] BPF register bounds logic and testing improvements Alexei Starovoitov
2023-10-31 5:19 ` Andrii Nakryiko
2023-11-01 12:37 ` Paul Chaignon
2023-11-01 17:13 ` Andrii Nakryiko
2023-11-07 6:37 ` Harishankar Vishwanathan
2023-11-07 16:38 ` Paul Chaignon
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