From: Marc Zyngier <marc.zyngier@arm.com>
To: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
kvmarm@lists.cs.columbia.edu
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
James Morse <James.Morse@arm.com>
Subject: Re: [PATCH v5 03/23] arm64: insn: Add encoder for bitwise operations using literals
Date: Mon, 12 Mar 2018 14:44:43 +0000 [thread overview]
Message-ID: <20aed108-d44e-89b9-0532-cad5fbb27f46@arm.com> (raw)
In-Reply-To: <20180301155538.26860-4-marc.zyngier@arm.com>
On 01/03/18 15:55, Marc Zyngier wrote:
> We lack a way to encode operations such as AND, ORR, EOR that take
> an immediate value. Doing so is quite involved, and is all about
> reverse engineering the decoding algorithm described in the
> pseudocode function DecodeBitMasks().
>
> This has been tested by feeding it all the possible literal values
> and comparing the output with that of GAS.
This is getting quite funny. Although the test harness was 100% matching
the GAS encoding...
[...]
> + /*
> + * Inverse of Replicate(). Try to spot a repeating pattern
> + * with a pow2 stride.
> + */
> + for (tmp = esz / 2; tmp >= 2; tmp /= 2) {
> + u64 emask = BIT(tmp) - 1;
> +
> + if ((imm & emask) != ((imm >> (tmp / 2)) & emask))
... I failed to move a fix from the test harness to the kernel code.
Total fail. Here, "(tmp / 2)" should really read "tmp".
Thanks to James for noticing the breakage.
M. (annoyed)
--
Jazz is not dead. It just smells funny...
WARNING: multiple messages have this Message-ID (diff)
From: marc.zyngier@arm.com (Marc Zyngier)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 03/23] arm64: insn: Add encoder for bitwise operations using literals
Date: Mon, 12 Mar 2018 14:44:43 +0000 [thread overview]
Message-ID: <20aed108-d44e-89b9-0532-cad5fbb27f46@arm.com> (raw)
In-Reply-To: <20180301155538.26860-4-marc.zyngier@arm.com>
On 01/03/18 15:55, Marc Zyngier wrote:
> We lack a way to encode operations such as AND, ORR, EOR that take
> an immediate value. Doing so is quite involved, and is all about
> reverse engineering the decoding algorithm described in the
> pseudocode function DecodeBitMasks().
>
> This has been tested by feeding it all the possible literal values
> and comparing the output with that of GAS.
This is getting quite funny. Although the test harness was 100% matching
the GAS encoding...
[...]
> + /*
> + * Inverse of Replicate(). Try to spot a repeating pattern
> + * with a pow2 stride.
> + */
> + for (tmp = esz / 2; tmp >= 2; tmp /= 2) {
> + u64 emask = BIT(tmp) - 1;
> +
> + if ((imm & emask) != ((imm >> (tmp / 2)) & emask))
... I failed to move a fix from the test harness to the kernel code.
Total fail. Here, "(tmp / 2)" should really read "tmp".
Thanks to James for noticing the breakage.
M. (annoyed)
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2018-03-12 14:44 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-01 15:55 [PATCH v5 00/23] KVM/arm64: Randomise EL2 mappings (variant 3a mitigation) Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 01/23] arm64: alternatives: Add dynamic patching feature Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-07 18:09 ` Catalin Marinas
2018-03-07 18:09 ` Catalin Marinas
2018-03-01 15:55 ` [PATCH v5 02/23] arm64: insn: Add N immediate encoding Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-07 18:09 ` Catalin Marinas
2018-03-07 18:09 ` Catalin Marinas
2018-03-01 15:55 ` [PATCH v5 03/23] arm64: insn: Add encoder for bitwise operations using literals Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-07 18:10 ` Catalin Marinas
2018-03-07 18:10 ` Catalin Marinas
2018-03-12 14:44 ` Marc Zyngier [this message]
2018-03-12 14:44 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 04/23] arm64: KVM: Dynamically patch the kernel/hyp VA mask Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-07 18:10 ` Catalin Marinas
2018-03-07 18:10 ` Catalin Marinas
2018-03-01 15:55 ` [PATCH v5 05/23] arm64: cpufeatures: Drop the ARM64_HYP_OFFSET_LOW feature flag Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-07 18:11 ` Catalin Marinas
2018-03-07 18:11 ` Catalin Marinas
2018-03-13 8:44 ` Suzuki K Poulose
2018-03-13 8:44 ` Suzuki K Poulose
2018-03-01 15:55 ` [PATCH v5 06/23] KVM: arm/arm64: Do not use kern_hyp_va() with kvm_vgic_global_state Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 07/23] KVM: arm/arm64: Demote HYP VA range display to being a debug feature Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 08/23] KVM: arm/arm64: Move ioremap calls to create_hyp_io_mappings Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-13 9:03 ` Suzuki K Poulose
2018-03-01 15:55 ` [PATCH v5 09/23] KVM: arm/arm64: Keep GICv2 HYP VAs in kvm_vgic_global_state Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-13 9:35 ` Suzuki K Poulose
2018-03-13 9:35 ` Suzuki K Poulose
2018-03-13 11:40 ` Marc Zyngier
2018-03-13 11:40 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 10/23] KVM: arm/arm64: Move HYP IO VAs to the "idmap" range Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-09 18:59 ` James Morse
2018-03-09 18:59 ` James Morse
2018-03-12 14:02 ` Marc Zyngier
2018-03-12 14:02 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 11/23] arm64; insn: Add encoder for the EXTR instruction Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-07 18:12 ` Catalin Marinas
2018-03-07 18:12 ` Catalin Marinas
2018-03-01 15:55 ` [PATCH v5 12/23] arm64: insn: Allow ADD/SUB (immediate) with LSL #12 Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-07 18:13 ` Catalin Marinas
2018-03-07 18:13 ` Catalin Marinas
2018-03-01 15:55 ` [PATCH v5 13/23] arm64: KVM: Dynamically compute the HYP VA mask Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 14/23] arm64: KVM: Introduce EL2 VA randomisation Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-13 11:31 ` James Morse
2018-03-13 11:31 ` James Morse
2018-03-13 11:48 ` James Morse
2018-03-13 11:48 ` James Morse
2018-03-01 15:55 ` [PATCH v5 15/23] arm64: Update the KVM memory map documentation Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 16/23] arm64: KVM: Move vector offsetting from hyp-init.S to kvm_get_hyp_vector Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 17/23] arm64: KVM: Move stashing of x0/x1 into the vector code itself Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 18/23] arm64: KVM: Add epilogue branching to the vector code Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-08 13:59 ` Catalin Marinas
2018-03-08 13:59 ` Catalin Marinas
2018-03-01 15:55 ` [PATCH v5 19/23] arm64: KVM: Allow far branches from vector slots to the main vectors Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-08 13:59 ` Catalin Marinas
2018-03-08 13:59 ` Catalin Marinas
2018-03-12 18:27 ` James Morse
2018-03-12 18:27 ` James Morse
2018-03-12 19:43 ` Marc Zyngier
2018-03-12 19:43 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 20/23] arm/arm64: KVM: Introduce EL2-specific executable mappings Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 21/23] arm64: Make BP hardening slot counter available Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 22/23] arm64: KVM: Allow mapping of vectors outside of the RAM region Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
2018-03-08 17:54 ` Andrew Jones
2018-03-08 17:54 ` Andrew Jones
2018-03-13 10:30 ` Marc Zyngier
2018-03-13 10:30 ` Marc Zyngier
2018-03-13 11:14 ` Andrew Jones
2018-03-13 11:14 ` Andrew Jones
2018-03-09 18:59 ` James Morse
2018-03-09 18:59 ` James Morse
2018-03-12 14:23 ` Marc Zyngier
2018-03-12 14:23 ` Marc Zyngier
2018-03-14 11:40 ` James Morse
2018-03-14 11:40 ` James Morse
2018-03-14 12:02 ` Marc Zyngier
2018-03-14 12:02 ` Marc Zyngier
2018-03-01 15:55 ` [PATCH v5 23/23] arm64: Enable ARM64_HARDEN_EL2_VECTORS on Cortex-A57 and A72 Marc Zyngier
2018-03-01 15:55 ` Marc Zyngier
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