From: Catalin Marinas <catalin.marinas@arm.com> To: Dave Martin <Dave.Martin@arm.com> Cc: linux-arm-kernel@lists.infradead.org, "Will Deacon" <will.deacon@arm.com>, "Ard Biesheuvel" <ard.biesheuvel@linaro.org>, "Alex Bennée" <alex.bennee@linaro.org>, "Szabolcs Nagy" <szabolcs.nagy@arm.com>, "Richard Sandiford" <richard.sandiford@arm.com>, kvmarm@lists.cs.columbia.edu, libc-alpha@sourceware.org, linux-arch@vger.kernel.org Subject: Re: [PATCH v2 11/28] arm64/sve: Core task context handling Date: Wed, 13 Sep 2017 10:26:05 -0700 [thread overview] Message-ID: <20170913172605.hjrwjf34kyy7coh4@localhost> (raw) In-Reply-To: <1504198860-12951-12-git-send-email-Dave.Martin@arm.com> On Thu, Aug 31, 2017 at 06:00:43PM +0100, Dave P Martin wrote: > +el0_sve_acc: > + /* > + * Scalable Vector Extension access > + */ > + enable_dbg > + ct_user_exit > + mov x0, x25 > + mov x1, sp > + bl do_sve_acc > + b ret_to_user I think do_sve_acc() runs with interrupts disabled. We may have some high latency for large SVE states. > +/* > + * Trapped SVE access > + */ > +void do_sve_acc(unsigned int esr, struct pt_regs *regs) > +{ > + /* Even if we chose not to use SVE, the hardware could still trap: */ > + if (unlikely(!system_supports_sve()) || WARN_ON(is_compat_task())) { > + force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0); > + return; > + } > + > + task_fpsimd_save(); > + > + sve_alloc(current); > + fpsimd_to_sve(current); > + if (test_and_set_thread_flag(TIF_SVE)) > + WARN_ON(1); /* SVE access shouldn't have trapped */ > + > + task_fpsimd_load(); > +} When this function is entered, do we expect TIF_SVE to always be cleared? It's worth adding a comment on the expected conditions. If that's the case, task_fpsimd_save() would only save the FPSIMD state which is fine. However, you subsequently transfer the FPSIMD state to SVE, set TIF_SVE and restore the full SVE state. If we don't care about the SVE state here, can we call task_fpsimd_load() *before* setting TIF_SVE? I may as well have confused myself with the state bouncing between FPSIMD and SVE (more reasons to document the data flow better ;)). -- Catalin
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From: catalin.marinas@arm.com (Catalin Marinas) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 11/28] arm64/sve: Core task context handling Date: Wed, 13 Sep 2017 10:26:05 -0700 [thread overview] Message-ID: <20170913172605.hjrwjf34kyy7coh4@localhost> (raw) In-Reply-To: <1504198860-12951-12-git-send-email-Dave.Martin@arm.com> On Thu, Aug 31, 2017 at 06:00:43PM +0100, Dave P Martin wrote: > +el0_sve_acc: > + /* > + * Scalable Vector Extension access > + */ > + enable_dbg > + ct_user_exit > + mov x0, x25 > + mov x1, sp > + bl do_sve_acc > + b ret_to_user I think do_sve_acc() runs with interrupts disabled. We may have some high latency for large SVE states. > +/* > + * Trapped SVE access > + */ > +void do_sve_acc(unsigned int esr, struct pt_regs *regs) > +{ > + /* Even if we chose not to use SVE, the hardware could still trap: */ > + if (unlikely(!system_supports_sve()) || WARN_ON(is_compat_task())) { > + force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0); > + return; > + } > + > + task_fpsimd_save(); > + > + sve_alloc(current); > + fpsimd_to_sve(current); > + if (test_and_set_thread_flag(TIF_SVE)) > + WARN_ON(1); /* SVE access shouldn't have trapped */ > + > + task_fpsimd_load(); > +} When this function is entered, do we expect TIF_SVE to always be cleared? It's worth adding a comment on the expected conditions. If that's the case, task_fpsimd_save() would only save the FPSIMD state which is fine. However, you subsequently transfer the FPSIMD state to SVE, set TIF_SVE and restore the full SVE state. If we don't care about the SVE state here, can we call task_fpsimd_load() *before* setting TIF_SVE? I may as well have confused myself with the state bouncing between FPSIMD and SVE (more reasons to document the data flow better ;)). -- Catalin
next prev parent reply other threads:[~2017-09-13 17:26 UTC|newest] Thread overview: 224+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-08-31 17:00 [PATCH v2 00/28] ARM Scalable Vector Extension (SVE) Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-08-31 17:00 ` [PATCH v2 01/28] regset: Add support for dynamically sized regsets Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-08-31 17:00 ` [PATCH v2 02/28] arm64: KVM: Hide unsupported AArch64 CPU features from guests Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-13 14:37 ` Alex Bennée 2017-09-13 14:37 ` Alex Bennée 2017-09-13 14:37 ` Alex Bennée 2017-09-15 0:04 ` Dave Martin 2017-09-15 0:04 ` Dave Martin 2017-08-31 17:00 ` [PATCH v2 03/28] arm64: efi: Add missing Kconfig dependency on KERNEL_MODE_NEON Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-08-31 17:00 ` [PATCH v2 04/28] arm64: Port deprecated instruction emulation to new sysctl interface Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-08-31 17:00 ` [PATCH v2 05/28] arm64: fpsimd: Simplify uses of {set,clear}_ti_thread_flag() Dave Martin 2017-08-31 17:00 ` [PATCH v2 05/28] arm64: fpsimd: Simplify uses of {set, clear}_ti_thread_flag() Dave Martin 2017-08-31 17:00 ` [PATCH v2 06/28] arm64/sve: System register and exception syndrome definitions Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-13 14:48 ` Alex Bennée 2017-09-13 14:48 ` Alex Bennée 2017-09-13 14:48 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 07/28] arm64/sve: Low-level SVE architectural state manipulation functions Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-13 15:39 ` Alex Bennée 2017-09-13 15:39 ` Alex Bennée 2017-09-13 15:39 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 08/28] arm64/sve: Kconfig update and conditional compilation support Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-08-31 17:00 ` [PATCH v2 09/28] arm64/sve: Signal frame and context structure definition Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-13 13:36 ` Catalin Marinas 2017-09-13 13:36 ` Catalin Marinas 2017-09-13 21:33 ` Dave Martin 2017-09-13 21:33 ` Dave Martin 2017-08-31 17:00 ` [PATCH v2 10/28] arm64/sve: Low-level CPU setup Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-13 13:32 ` Catalin Marinas 2017-09-13 13:32 ` Catalin Marinas 2017-09-13 19:21 ` Dave Martin 2017-09-13 19:21 ` Dave Martin 2017-09-13 19:21 ` Dave Martin 2017-10-05 10:47 ` Dave Martin 2017-10-05 10:47 ` Dave Martin 2017-10-05 11:04 ` Suzuki K Poulose 2017-10-05 11:04 ` Suzuki K Poulose 2017-10-05 11:22 ` Dave Martin 2017-10-05 11:22 ` Dave Martin 2017-08-31 17:00 ` [PATCH v2 11/28] arm64/sve: Core task context handling Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-13 14:33 ` Catalin Marinas 2017-09-13 14:33 ` Catalin Marinas 2017-09-14 19:55 ` Dave Martin 2017-09-14 19:55 ` Dave Martin 2017-09-20 13:58 ` Catalin Marinas 2017-09-20 13:58 ` Catalin Marinas 2017-10-03 11:11 ` Dave Martin 2017-10-03 11:11 ` Dave Martin 2017-10-04 17:29 ` Catalin Marinas 2017-10-04 17:29 ` Catalin Marinas 2017-10-03 11:33 ` Dave Martin 2017-10-03 11:33 ` Dave Martin 2017-10-05 11:28 ` Catalin Marinas 2017-10-05 11:28 ` Catalin Marinas 2017-10-06 13:10 ` Dave Martin 2017-10-06 13:10 ` Dave Martin 2017-10-06 13:36 ` Catalin Marinas 2017-10-06 13:36 ` Catalin Marinas 2017-10-06 15:15 ` Dave Martin 2017-10-06 15:15 ` Dave Martin 2017-10-06 15:33 ` Catalin Marinas 2017-10-06 15:33 ` Catalin Marinas 2017-09-13 17:26 ` Catalin Marinas [this message] 2017-09-13 17:26 ` Catalin Marinas 2017-09-13 19:17 ` Dave Martin 2017-09-13 19:17 ` Dave Martin 2017-09-13 22:21 ` Catalin Marinas 2017-09-13 22:21 ` Catalin Marinas 2017-09-14 19:40 ` Dave Martin 2017-09-14 19:40 ` Dave Martin 2017-09-19 17:13 ` Catalin Marinas 2017-09-19 17:13 ` Catalin Marinas 2017-08-31 17:00 ` [PATCH v2 12/28] arm64/sve: Support vector length resetting for new processes Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 8:47 ` Alex Bennée 2017-09-14 8:47 ` Alex Bennée 2017-09-14 8:47 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 13/28] arm64/sve: Signal handling support Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 9:30 ` Alex Bennée 2017-09-14 9:30 ` Alex Bennée 2017-09-14 9:30 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 14/28] arm64/sve: Backend logic for setting the vector length Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-13 17:29 ` Catalin Marinas 2017-09-13 17:29 ` Catalin Marinas 2017-09-13 19:06 ` Dave Martin 2017-09-13 19:06 ` Dave Martin 2017-09-13 22:11 ` Catalin Marinas 2017-09-13 22:11 ` Catalin Marinas 2017-10-05 16:42 ` Dave Martin 2017-10-05 16:42 ` Dave Martin 2017-10-05 16:53 ` Catalin Marinas 2017-10-05 16:53 ` Catalin Marinas 2017-10-05 17:04 ` Dave Martin 2017-10-05 17:04 ` Dave Martin 2017-09-20 10:57 ` Alan Hayward 2017-09-20 10:57 ` Alan Hayward 2017-09-20 10:59 ` Alan Hayward 2017-09-20 10:59 ` Alan Hayward 2017-09-20 11:09 ` Dave Martin 2017-09-20 11:09 ` Dave Martin 2017-09-20 18:08 ` Alan Hayward 2017-09-20 18:08 ` Alan Hayward 2017-09-21 11:19 ` Dave Martin 2017-09-21 11:19 ` Dave Martin 2017-09-21 11:57 ` Alan Hayward 2017-09-21 11:57 ` Alan Hayward 2017-08-31 17:00 ` [PATCH v2 15/28] arm64: cpufeature: Move sys_caps_initialised declarations Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 9:33 ` Alex Bennée 2017-09-14 9:33 ` Alex Bennée 2017-09-14 9:33 ` Alex Bennée 2017-09-14 9:35 ` Suzuki K Poulose 2017-09-14 9:35 ` Suzuki K Poulose 2017-08-31 17:00 ` [PATCH v2 16/28] arm64/sve: Probe SVE capabilities and usable vector lengths Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 9:45 ` Alex Bennée 2017-09-14 9:45 ` Alex Bennée 2017-09-14 9:45 ` Alex Bennée 2017-09-28 14:22 ` Dave Martin 2017-09-28 14:22 ` Dave Martin 2017-09-28 17:32 ` Alex Bennée 2017-09-28 17:32 ` Alex Bennée 2017-09-28 17:32 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 17/28] arm64/sve: Preserve SVE registers around kernel-mode NEON use Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 10:52 ` Alex Bennée 2017-09-14 10:52 ` Alex Bennée 2017-09-14 10:52 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 18/28] arm64/sve: Preserve SVE registers around EFI runtime service calls Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 11:01 ` Alex Bennée 2017-09-14 11:01 ` Alex Bennée 2017-09-14 11:01 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 19/28] arm64/sve: ptrace and ELF coredump support Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-06 16:21 ` Okamoto, Takayuki 2017-09-06 16:21 ` Okamoto, Takayuki 2017-09-06 18:16 ` Dave Martin 2017-09-06 18:16 ` Dave Martin 2017-09-07 5:11 ` Okamoto, Takayuki 2017-09-07 5:11 ` Okamoto, Takayuki 2017-09-07 5:11 ` Okamoto, Takayuki 2017-09-08 13:11 ` Dave Martin 2017-09-08 13:11 ` Dave Martin 2017-09-14 12:57 ` Alex Bennée 2017-09-14 12:57 ` Alex Bennée 2017-09-14 12:57 ` Alex Bennée 2017-09-28 14:57 ` Dave Martin 2017-09-28 14:57 ` Dave Martin 2017-09-29 12:46 ` Dave Martin 2017-09-29 12:46 ` Dave Martin 2017-08-31 17:00 ` [PATCH v2 20/28] arm64/sve: Add prctl controls for userspace vector length management Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 13:02 ` Alex Bennée 2017-09-14 13:02 ` Alex Bennée 2017-09-14 13:02 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 21/28] arm64/sve: Add sysctl to set the default vector length for new processes Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 13:05 ` Alex Bennée 2017-09-14 13:05 ` Alex Bennée 2017-09-14 13:05 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 22/28] arm64/sve: KVM: Prevent guests from using SVE Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 13:28 ` Alex Bennée 2017-09-14 13:28 ` Alex Bennée 2017-09-14 13:28 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 23/28] arm64/sve: KVM: Treat guest SVE use as undefined instruction execution Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 13:30 ` Alex Bennée 2017-09-14 13:30 ` Alex Bennée 2017-09-14 13:30 ` Alex Bennée 2017-09-14 13:31 ` Alex Bennée 2017-09-14 13:31 ` Alex Bennée 2017-09-14 13:31 ` Alex Bennée 2017-09-29 13:00 ` Dave Martin 2017-09-29 13:00 ` Dave Martin 2017-09-29 14:43 ` Alex Bennée 2017-09-29 14:43 ` Alex Bennée 2017-09-29 14:43 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-09-14 13:32 ` Alex Bennée 2017-09-14 13:32 ` Alex Bennée 2017-09-14 13:32 ` Alex Bennée 2017-08-31 17:00 ` [PATCH v2 25/28] arm64/sve: Detect SVE and activate runtime support Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-08-31 17:00 ` [PATCH v2 26/28] arm64/sve: Add documentation Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-10-05 16:39 ` Szabolcs Nagy 2017-10-05 16:39 ` Szabolcs Nagy 2017-10-05 17:02 ` Dave Martin 2017-10-05 17:02 ` Dave Martin 2017-10-06 15:43 ` Szabolcs Nagy 2017-10-06 15:43 ` Szabolcs Nagy 2017-10-06 17:37 ` Dave Martin 2017-10-06 17:37 ` Dave Martin 2017-10-09 9:34 ` Alex Bennée 2017-10-09 9:34 ` Alex Bennée 2017-10-09 9:34 ` Alex Bennée 2017-10-09 9:49 ` Dave Martin 2017-10-09 9:49 ` Dave Martin 2017-10-09 14:07 ` Alex Bennée 2017-10-09 14:07 ` Alex Bennée 2017-10-09 14:07 ` Alex Bennée 2017-10-09 16:20 ` Dave Martin 2017-10-09 16:20 ` Dave Martin 2017-08-31 17:00 ` [RFC PATCH v2 27/28] arm64: signal: Report signal frame size to userspace via auxv Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-08-31 17:00 ` Dave Martin 2017-08-31 17:01 ` [RFC PATCH v2 28/28] arm64/sve: signal: Include SVE when computing AT_MINSIGSTKSZ Dave Martin 2017-08-31 17:01 ` Dave Martin
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