From: "Jose E. Marchesi" <jose.marchesi@oracle.com>
To: David Faust <david.faust@oracle.com>
Cc: binutils@sourceware.org
Subject: Re: [PATCH] bpf: correct neg and neg32 instruction encoding
Date: Mon, 21 Aug 2023 19:05:11 +0200 [thread overview]
Message-ID: <87a5ukl41k.fsf@oracle.com> (raw)
In-Reply-To: <20230821170018.5704-1-david.faust@oracle.com> (David Faust's message of "Mon, 21 Aug 2023 10:00:18 -0700")
Hi Faust.
> The neg/neg32 BPF instructions always use BPF_SRC_K (=0) in their header
> source bit, despite operating on registers. If BPF_SRC_X (=1) is set,
> the instructions are rejected by the kernel.
>
> Because of this there are also no neg/neg32 instructions which operate
> on immediates, so remove them.
OK, thanks.
>
> bd434cc4d94ec3d2f9fc1e7c00c27b074f962bc1 was a similar fix in the old
> CGEN-based port, but was not carried forward in the new port.
>
> include/
> * opcode/bpf.h (enum bpf_insn_id): Remove spurious entries
> BPF_INSN_NEGI and BPF_INSN_NEG32I.
>
> opcodes/
> * bpf-opc.c (bpf_opcodes): Remove erroneous NEGI and NEG32I
> instructions.
>
> gas/
> * doc/c-bpf.texi (BPF Instructions): Remove erroneous neg and
> neg32 instructions operating on immediates.
> * testsuite/gas/bpf/alu.s: Adapt accordingly.
> * testsuite/gas/bpf/alu.d: Likewise.
> * testsuite/gas/bpf/alu-be.d: Likewise
> * testsuite/gas/bpf/alu32.s: Likewise.
> * testsuite/gas/bpf/alu32.d: Likewise.
> * testsuite/gas/bpf/alu32-be.d: Likewise.
> * testsuite/gas/bpf/alu-pseudoc.s: Likewise.
> * testsuite/gas/bpf/alu-pseudoc.d: Likewise.
> * testsuite/gas/bpf/alu-be-pseudoc.d: Likewise.
> * testsuite/gas/bpf/alu32-pseudoc.s: Likewise.
> * testsuite/gas/bpf/alu32-pseudoc.d: Likewise.
> * testsuite/gas/bpf/alu32-be-pseudoc.d: Likewise.
> ---
> gas/doc/c-bpf.texi | 16 ----------------
> gas/testsuite/gas/bpf/alu-be-pseudoc.d | 3 +--
> gas/testsuite/gas/bpf/alu-be.d | 3 +--
> gas/testsuite/gas/bpf/alu-pseudoc.d | 3 +--
> gas/testsuite/gas/bpf/alu-pseudoc.s | 4 ----
> gas/testsuite/gas/bpf/alu.d | 3 +--
> gas/testsuite/gas/bpf/alu.s | 1 -
> gas/testsuite/gas/bpf/alu32-be-pseudoc.d | 3 +--
> gas/testsuite/gas/bpf/alu32-be.d | 3 +--
> gas/testsuite/gas/bpf/alu32-pseudoc.d | 3 +--
> gas/testsuite/gas/bpf/alu32-pseudoc.s | 4 ----
> gas/testsuite/gas/bpf/alu32.d | 3 +--
> gas/testsuite/gas/bpf/alu32.s | 1 -
> include/opcode/bpf.h | 4 ++--
> opcodes/bpf-opc.c | 4 ----
> 15 files changed, 10 insertions(+), 48 deletions(-)
>
> diff --git a/gas/doc/c-bpf.texi b/gas/doc/c-bpf.texi
> index 75372de4ef4..bdd9fde0f5a 100644
> --- a/gas/doc/c-bpf.texi
> +++ b/gas/doc/c-bpf.texi
> @@ -256,17 +256,9 @@ registers.
> 64-bit right arithmetic shift, by @code{rs} or @code{imm32} bits.
>
> @item neg rd
> -@itemx neg rd, imm32
> @itemx rd = - rd
> -@itemx rd = - imm32
> 64-bit arithmetic negation.
>
> -Note that in the @code{rd = - imm32} syntax there must be at least
> -one white space between @code{-} and @code{imm32}. Otherwise the
> -instruction is parsed as a @code{mov rd, imm32} instruction with a
> -negative 32-bit immediate. This is a consequence of a syntactic
> -ambiguity in the pseudoc syntax.
> -
> @item mov rd, rs
> @itemx mov rd, imm32
> @itemx rd = rs
> @@ -363,17 +355,9 @@ in the same instruction.
> 32-bit right arithmetic shift, by @code{rs} or @code{imm32} bits.
>
> @item neg32 rd
> -@itemx neg32 rd, imm32
> @itemx rd = - rd
> -@itemx rd = - imm32
> 32-bit arithmetic negation.
>
> -Note that in the @code{rd = - imm32} syntax there must be at least
> -one white space between @code{-} and @code{imm32}. Otherwise the
> -instruction is parsed as a @code{mov32 rd, imm32} instruction with a
> -negative 32-bit immediate. This is a consequence of a syntactic
> -ambiguity in the pseudoc syntax.
> -
> @item mov32 rd, rs
> @itemx mov32 rd, imm32
> @itemx rd = rs
> diff --git a/gas/testsuite/gas/bpf/alu-be-pseudoc.d b/gas/testsuite/gas/bpf/alu-be-pseudoc.d
> index 0e9df07eb15..4c0f6ba9ca6 100644
> --- a/gas/testsuite/gas/bpf/alu-be-pseudoc.d
> +++ b/gas/testsuite/gas/bpf/alu-be-pseudoc.d
> @@ -56,7 +56,7 @@ Disassembly of section .text:
> 168: c7 30 00 00 ff ff fd 66 r3 s>>=0xfffffd66
> 170: c7 40 00 00 7e ad be ef r4 s>>=0x7eadbeef
> 178: cf 56 00 00 00 00 00 00 r5 s>>=r6
> - 180: 8f 20 00 00 00 00 00 00 r2=-r2
> + 180: 87 20 00 00 00 00 00 00 r2=-r2
> 188: d4 90 00 00 00 00 00 10 r9=le16 r9
> 190: d4 80 00 00 00 00 00 20 r8=le32 r8
> 198: d4 70 00 00 00 00 00 40 r7=le64 r7
> @@ -69,4 +69,3 @@ Disassembly of section .text:
> 1d0: d7 10 00 00 00 00 00 10 r1 = bswap16 r1
> 1d8: d7 20 00 00 00 00 00 20 r2 = bswap32 r2
> 1e0: d7 30 00 00 00 00 00 40 r3 = bswap64 r3
> - 1e8: b7 10 00 00 ff ff f1 00 r1=0xfffff100
> \ No newline at end of file
> diff --git a/gas/testsuite/gas/bpf/alu-be.d b/gas/testsuite/gas/bpf/alu-be.d
> index b961f3fe474..0d6a10f8ca3 100644
> --- a/gas/testsuite/gas/bpf/alu-be.d
> +++ b/gas/testsuite/gas/bpf/alu-be.d
> @@ -56,7 +56,7 @@ Disassembly of section .text:
> 168: c7 30 00 00 ff ff fd 66 arsh %r3,0xfffffd66
> 170: c7 40 00 00 7e ad be ef arsh %r4,0x7eadbeef
> 178: cf 56 00 00 00 00 00 00 arsh %r5,%r6
> - 180: 8f 20 00 00 00 00 00 00 neg %r2
> + 180: 87 20 00 00 00 00 00 00 neg %r2
> 188: d4 90 00 00 00 00 00 10 endle %r9,16
> 190: d4 80 00 00 00 00 00 20 endle %r8,32
> 198: d4 70 00 00 00 00 00 40 endle %r7,64
> @@ -69,4 +69,3 @@ Disassembly of section .text:
> 1d0: d7 10 00 00 00 00 00 10 bswap %r1,16
> 1d8: d7 20 00 00 00 00 00 20 bswap %r2,32
> 1e0: d7 30 00 00 00 00 00 40 bswap %r3,64
> - 1e8: 87 10 00 00 00 00 0f 00 neg %r1,0xf00
> \ No newline at end of file
> diff --git a/gas/testsuite/gas/bpf/alu-pseudoc.d b/gas/testsuite/gas/bpf/alu-pseudoc.d
> index bbd222c83ae..b5ab569563c 100644
> --- a/gas/testsuite/gas/bpf/alu-pseudoc.d
> +++ b/gas/testsuite/gas/bpf/alu-pseudoc.d
> @@ -56,7 +56,7 @@ Disassembly of section .text:
> 168: c7 03 00 00 66 fd ff ff r3 s>>=0xfffffd66
> 170: c7 04 00 00 ef be ad 7e r4 s>>=0x7eadbeef
> 178: cf 65 00 00 00 00 00 00 r5 s>>=r6
> - 180: 8f 02 00 00 00 00 00 00 r2=-r2
> + 180: 87 02 00 00 00 00 00 00 r2=-r2
> 188: d4 09 00 00 10 00 00 00 r9=le16 r9
> 190: d4 08 00 00 20 00 00 00 r8=le32 r8
> 198: d4 07 00 00 40 00 00 00 r7=le64 r7
> @@ -69,4 +69,3 @@ Disassembly of section .text:
> 1d0: d7 01 00 00 10 00 00 00 r1 = bswap16 r1
> 1d8: d7 02 00 00 20 00 00 00 r2 = bswap32 r2
> 1e0: d7 03 00 00 40 00 00 00 r3 = bswap64 r3
> - 1e8: b7 01 00 00 00 f1 ff ff r1=0xfffff100
> diff --git a/gas/testsuite/gas/bpf/alu-pseudoc.s b/gas/testsuite/gas/bpf/alu-pseudoc.s
> index abd8ddcc38e..323a6522f22 100644
> --- a/gas/testsuite/gas/bpf/alu-pseudoc.s
> +++ b/gas/testsuite/gas/bpf/alu-pseudoc.s
> @@ -61,7 +61,3 @@
> r1 = bswap16 r1
> r2 = bswap32 r2
> r3 = bswap64 r3
> - ;; Note that the next instruction gets processed by the GAS
> - ;; preprocessor into r1 =-0xf00, which parses into a %dr = %i32
> - ;; instruction instead of a neg :/
> - r1 = - 0xf00
> diff --git a/gas/testsuite/gas/bpf/alu.d b/gas/testsuite/gas/bpf/alu.d
> index e4afdab0d50..f6bead38f4b 100644
> --- a/gas/testsuite/gas/bpf/alu.d
> +++ b/gas/testsuite/gas/bpf/alu.d
> @@ -56,7 +56,7 @@ Disassembly of section .text:
> 168: c7 03 00 00 66 fd ff ff arsh %r3,0xfffffd66
> 170: c7 04 00 00 ef be ad 7e arsh %r4,0x7eadbeef
> 178: cf 65 00 00 00 00 00 00 arsh %r5,%r6
> - 180: 8f 02 00 00 00 00 00 00 neg %r2
> + 180: 87 02 00 00 00 00 00 00 neg %r2
> 188: d4 09 00 00 10 00 00 00 endle %r9,16
> 190: d4 08 00 00 20 00 00 00 endle %r8,32
> 198: d4 07 00 00 40 00 00 00 endle %r7,64
> @@ -69,4 +69,3 @@ Disassembly of section .text:
> 1d0: d7 01 00 00 10 00 00 00 bswap %r1,16
> 1d8: d7 02 00 00 20 00 00 00 bswap %r2,32
> 1e0: d7 03 00 00 40 00 00 00 bswap %r3,64
> - 1e8: 87 01 00 00 00 0f 00 00 neg %r1,0xf00
> \ No newline at end of file
> diff --git a/gas/testsuite/gas/bpf/alu.s b/gas/testsuite/gas/bpf/alu.s
> index d0bf5600209..2d8d22da0e1 100644
> --- a/gas/testsuite/gas/bpf/alu.s
> +++ b/gas/testsuite/gas/bpf/alu.s
> @@ -61,4 +61,3 @@
> bswap %r1, 16
> bswap %r2, 32
> bswap %r3, 64
> - neg %r1, 0xf00
> diff --git a/gas/testsuite/gas/bpf/alu32-be-pseudoc.d b/gas/testsuite/gas/bpf/alu32-be-pseudoc.d
> index 7f5e70071fc..150ed4c0732 100644
> --- a/gas/testsuite/gas/bpf/alu32-be-pseudoc.d
> +++ b/gas/testsuite/gas/bpf/alu32-be-pseudoc.d
> @@ -56,8 +56,7 @@ Disassembly of section .text:
> 168: c4 30 00 00 ff ff fd 66 w3 s>>=0xfffffd66
> 170: c4 40 00 00 7e ad be ef w4 s>>=0x7eadbeef
> 178: cc 56 00 00 00 00 00 00 w5 s>>=w6
> - 180: 8c 20 00 00 00 00 00 00 w2=-w2
> + 180: 84 20 00 00 00 00 00 00 w2=-w2
> 188: bc 12 00 08 00 00 00 00 w1 = \(s8\) w2
> 190: bc 12 00 10 00 00 00 00 w1 = \(s16\) w2
> 198: bc 12 00 20 00 00 00 00 w1 = \(s32\) w2
> - 1a0: b4 10 00 00 ff ff f1 00 w1=0xfffff100
> \ No newline at end of file
> diff --git a/gas/testsuite/gas/bpf/alu32-be.d b/gas/testsuite/gas/bpf/alu32-be.d
> index 9799664b27a..650432dec10 100644
> --- a/gas/testsuite/gas/bpf/alu32-be.d
> +++ b/gas/testsuite/gas/bpf/alu32-be.d
> @@ -56,8 +56,7 @@ Disassembly of section .text:
> 168: c4 30 00 00 ff ff fd 66 arsh32 %r3,0xfffffd66
> 170: c4 40 00 00 7e ad be ef arsh32 %r4,0x7eadbeef
> 178: cc 56 00 00 00 00 00 00 arsh32 %r5,%r6
> - 180: 8c 20 00 00 00 00 00 00 neg32 %r2
> + 180: 84 20 00 00 00 00 00 00 neg32 %r2
> 188: bc 12 00 08 00 00 00 00 movs32 %r1,%r2,8
> 190: bc 12 00 10 00 00 00 00 movs32 %r1,%r2,16
> 198: bc 12 00 20 00 00 00 00 movs32 %r1,%r2,32
> - 1a0: 84 10 00 00 00 00 0f 00 neg32 %r1,0xf00
> diff --git a/gas/testsuite/gas/bpf/alu32-pseudoc.d b/gas/testsuite/gas/bpf/alu32-pseudoc.d
> index cc4e010b201..4aa90a1a608 100644
> --- a/gas/testsuite/gas/bpf/alu32-pseudoc.d
> +++ b/gas/testsuite/gas/bpf/alu32-pseudoc.d
> @@ -56,8 +56,7 @@ Disassembly of section .text:
> 168: c4 03 00 00 66 fd ff ff w3 s>>=0xfffffd66
> 170: c4 04 00 00 ef be ad 7e w4 s>>=0x7eadbeef
> 178: cc 65 00 00 00 00 00 00 w5 s>>=w6
> - 180: 8c 02 00 00 00 00 00 00 w2=-w2
> + 180: 84 02 00 00 00 00 00 00 w2=-w2
> 188: bc 21 08 00 00 00 00 00 w1 = \(s8\) w2
> 190: bc 21 10 00 00 00 00 00 w1 = \(s16\) w2
> 198: bc 21 20 00 00 00 00 00 w1 = \(s32\) w2
> - 1a0: b4 01 00 00 00 f1 ff ff w1=0xfffff100
> diff --git a/gas/testsuite/gas/bpf/alu32-pseudoc.s b/gas/testsuite/gas/bpf/alu32-pseudoc.s
> index 98d586a48e6..46c4e15a4b7 100644
> --- a/gas/testsuite/gas/bpf/alu32-pseudoc.s
> +++ b/gas/testsuite/gas/bpf/alu32-pseudoc.s
> @@ -52,7 +52,3 @@
> w1 = (s8) w2
> w1 = (s16) w2
> w1 = (s32) w2
> - ;; Note that the next instruction gets processed by the GAS
> - ;; preprocessor into w1 =-0xf00, which parses into a %dw = %i32
> - ;; instruction instead of a neg :/
> - w1 = - 0xf00
> diff --git a/gas/testsuite/gas/bpf/alu32.d b/gas/testsuite/gas/bpf/alu32.d
> index 25484381aeb..25f84a167e4 100644
> --- a/gas/testsuite/gas/bpf/alu32.d
> +++ b/gas/testsuite/gas/bpf/alu32.d
> @@ -56,8 +56,7 @@ Disassembly of section .text:
> 168: c4 03 00 00 66 fd ff ff arsh32 %r3,0xfffffd66
> 170: c4 04 00 00 ef be ad 7e arsh32 %r4,0x7eadbeef
> 178: cc 65 00 00 00 00 00 00 arsh32 %r5,%r6
> - 180: 8c 02 00 00 00 00 00 00 neg32 %r2
> + 180: 84 02 00 00 00 00 00 00 neg32 %r2
> 188: bc 21 08 00 00 00 00 00 movs32 %r1,%r2,8
> 190: bc 21 10 00 00 00 00 00 movs32 %r1,%r2,16
> 198: bc 21 20 00 00 00 00 00 movs32 %r1,%r2,32
> - 1a0: 84 01 00 00 00 0f 00 00 neg32 %r1,0xf00
> \ No newline at end of file
> diff --git a/gas/testsuite/gas/bpf/alu32.s b/gas/testsuite/gas/bpf/alu32.s
> index fd1d528ba21..291f9ced6a7 100644
> --- a/gas/testsuite/gas/bpf/alu32.s
> +++ b/gas/testsuite/gas/bpf/alu32.s
> @@ -52,4 +52,3 @@
> movs32 %r1,%r2,8
> movs32 %r1,%r2,16
> movs32 %r1,%r2,32
> - neg32 %r1, 0xf00
> diff --git a/include/opcode/bpf.h b/include/opcode/bpf.h
> index 6decae4a9a3..a8a95955768 100644
> --- a/include/opcode/bpf.h
> +++ b/include/opcode/bpf.h
> @@ -168,7 +168,7 @@ enum bpf_insn_id
> BPF_INSN_SMODR, BPF_INSN_SMODI, BPF_INSN_DIVR, BPF_INSN_DIVI,
> BPF_INSN_MODR, BPF_INSN_MODI, BPF_INSN_ORR, BPF_INSN_ORI,
> BPF_INSN_ANDR, BPF_INSN_ANDI, BPF_INSN_XORR, BPF_INSN_XORI,
> - BPF_INSN_NEGR, BPF_INSN_NEGI, BPF_INSN_LSHR, BPF_INSN_LSHI,
> + BPF_INSN_NEGR, BPF_INSN_LSHR, BPF_INSN_LSHI,
> BPF_INSN_RSHR, BPF_INSN_RSHI, BPF_INSN_ARSHR, BPF_INSN_ARSHI,
> BPF_INSN_MOVS8R, BPF_INSN_MOVS16R, BPF_INSN_MOVS32R,
> BPF_INSN_MOVR, BPF_INSN_MOVI,
> @@ -178,7 +178,7 @@ enum bpf_insn_id
> BPF_INSN_SMOD32R, BPF_INSN_SMOD32I, BPF_INSN_DIV32R, BPF_INSN_DIV32I,
> BPF_INSN_MOD32R, BPF_INSN_MOD32I, BPF_INSN_OR32R, BPF_INSN_OR32I,
> BPF_INSN_AND32R, BPF_INSN_AND32I, BPF_INSN_XOR32R, BPF_INSN_XOR32I,
> - BPF_INSN_NEG32R, BPF_INSN_NEG32I, BPF_INSN_LSH32R, BPF_INSN_LSH32I,
> + BPF_INSN_NEG32R, BPF_INSN_LSH32R, BPF_INSN_LSH32I,
> BPF_INSN_RSH32R, BPF_INSN_RSH32I, BPF_INSN_ARSH32R, BPF_INSN_ARSH32I,
> BPF_INSN_MOVS328R, BPF_INSN_MOVS3216R, BPF_INSN_MOVS3232R,
> BPF_INSN_MOV32R, BPF_INSN_MOV32I,
> diff --git a/opcodes/bpf-opc.c b/opcodes/bpf-opc.c
> index 3d6dccbd005..7fcec62234e 100644
> --- a/opcodes/bpf-opc.c
> +++ b/opcodes/bpf-opc.c
> @@ -74,8 +74,6 @@ const struct bpf_opcode bpf_opcodes[] =
> {BPF_INSN_XORI, "xor%W%dr , %i32", "%dr ^= %i32",
> BPF_V1, BPF_CODE, BPF_CLASS_ALU64|BPF_CODE_XOR|BPF_SRC_K},
> {BPF_INSN_NEGR, "neg%W%dr", "%dr = - %dr",
> - BPF_V1, BPF_CODE, BPF_CLASS_ALU64|BPF_CODE_NEG|BPF_SRC_X},
> - {BPF_INSN_NEGI, "neg%W%dr , %i32", "%dr = -%W%i32",
> BPF_V1, BPF_CODE, BPF_CLASS_ALU64|BPF_CODE_NEG|BPF_SRC_K},
> {BPF_INSN_LSHR, "lsh%W%dr , %sr", "%dr <<= %sr",
> BPF_V1, BPF_CODE, BPF_CLASS_ALU64|BPF_CODE_LSH|BPF_SRC_X},
> @@ -142,8 +140,6 @@ const struct bpf_opcode bpf_opcodes[] =
> {BPF_INSN_XOR32I, "xor32%W%dr , %i32", "%dw ^= %i32",
> BPF_V1, BPF_CODE, BPF_CLASS_ALU|BPF_CODE_XOR|BPF_SRC_K},
> {BPF_INSN_NEG32R, "neg32%W%dr", "%dw = - %dw",
> - BPF_V1, BPF_CODE, BPF_CLASS_ALU|BPF_CODE_NEG|BPF_SRC_X},
> - {BPF_INSN_NEG32I, "neg32%W%dr , %i32", "%dw = -%W%i32",
> BPF_V1, BPF_CODE, BPF_CLASS_ALU|BPF_CODE_NEG|BPF_SRC_K},
> {BPF_INSN_LSH32R, "lsh32%W%dr , %sr", "%dw <<= %sw",
> BPF_V1, BPF_CODE, BPF_CLASS_ALU|BPF_CODE_LSH|BPF_SRC_X},
prev parent reply other threads:[~2023-08-21 17:05 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-21 17:00 David Faust
2023-08-21 17:05 ` Jose E. Marchesi [this message]
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