linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Will Deacon <will.deacon@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
	mark.rutland@arm.com, ard.biesheuvel@linaro.org,
	sboyd@codeaurora.org, dave.hansen@linux.intel.com,
	keescook@chromium.org, msalter@redhat.com, labbott@redhat.com,
	tglx@linutronix.de, Will Deacon <will.deacon@arm.com>
Subject: [PATCH v2 18/18] perf: arm_spe: Disallow userspace profiling when arm_kernel_unmapped_at_el0()
Date: Thu, 30 Nov 2017 16:39:46 +0000	[thread overview]
Message-ID: <1512059986-21325-19-git-send-email-will.deacon@arm.com> (raw)
In-Reply-To: <1512059986-21325-1-git-send-email-will.deacon@arm.com>

When running with the kernel unmapped whilst at EL0, the virtually-addressed
SPE buffer is also unmapped, which can lead to buffer faults if userspace
profiling is enabled.

This patch prohibits SPE profiling of userspace when
arm_kernel_unmapped_at_el0().

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 drivers/perf/arm_spe_pmu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
index 8ce262fc2561..c028db8973a4 100644
--- a/drivers/perf/arm_spe_pmu.c
+++ b/drivers/perf/arm_spe_pmu.c
@@ -675,6 +675,13 @@ static int arm_spe_pmu_event_init(struct perf_event *event)
 		return -EOPNOTSUPP;
 
 	/*
+	 * If kernelspace is unmapped when running at EL0, then the SPE
+	 * buffer will fault and prematurely terminate the AUX session.
+	 */
+	if (arm64_kernel_unmapped_at_el0() && !attr->exclude_user)
+		dev_warn_once(&spe_pmu->pdev->dev, "unable to write to profiling buffer from EL0. Try passing \"kaiser=off\" on the kernel command line");
+
+	/*
 	 * Feedback-directed frequency throttling doesn't work when we
 	 * have a buffer of samples. We'd need to manually count the
 	 * samples in the buffer when it fills up and adjust the event
-- 
2.1.4

  parent reply	other threads:[~2017-11-30 16:40 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-30 16:39 [PATCH v2 00/18] arm64: Unmap the kernel whilst running in userspace (KAISER) Will Deacon
2017-11-30 16:39 ` [PATCH v2 01/18] arm64: mm: Use non-global mappings for kernel space Will Deacon
2017-11-30 16:39 ` [PATCH v2 02/18] arm64: mm: Temporarily disable ARM64_SW_TTBR0_PAN Will Deacon
2017-11-30 16:39 ` [PATCH v2 03/18] arm64: mm: Move ASID from TTBR0 to TTBR1 Will Deacon
2017-11-30 17:36   ` Mark Rutland
2017-11-30 16:39 ` [PATCH v2 04/18] arm64: mm: Remove pre_ttbr0_update_workaround for Falkor erratum #E1003 Will Deacon
2017-11-30 16:39 ` [PATCH v2 05/18] arm64: mm: Rename post_ttbr0_update_workaround Will Deacon
2017-11-30 16:39 ` [PATCH v2 06/18] arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN Will Deacon
2017-12-01 11:48   ` Mark Rutland
2017-11-30 16:39 ` [PATCH v2 07/18] arm64: mm: Allocate ASIDs in pairs Will Deacon
2017-11-30 16:39 ` [PATCH v2 08/18] arm64: mm: Add arm64_kernel_unmapped_at_el0 helper Will Deacon
2017-11-30 16:39 ` [PATCH v2 09/18] arm64: mm: Invalidate both kernel and user ASIDs when performing TLBI Will Deacon
2017-11-30 16:39 ` [PATCH v2 10/18] arm64: entry: Add exception trampoline page for exceptions from EL0 Will Deacon
2017-12-01 13:31   ` Mark Rutland
2017-12-06 10:25   ` Ard Biesheuvel
2017-11-30 16:39 ` [PATCH v2 11/18] arm64: mm: Map entry trampoline into trampoline and kernel page tables Will Deacon
2017-11-30 18:29   ` Mark Rutland
2017-11-30 16:39 ` [PATCH v2 12/18] arm64: entry: Explicitly pass exception level to kernel_ventry macro Will Deacon
2017-12-01 11:58   ` Mark Rutland
2017-12-01 17:51     ` Will Deacon
2017-12-01 18:00       ` Mark Rutland
2017-11-30 16:39 ` [PATCH v2 13/18] arm64: entry: Hook up entry trampoline to exception vectors Will Deacon
2017-12-01 13:53   ` Mark Rutland
2017-12-01 17:40     ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 14/18] arm64: erratum: Work around Falkor erratum #E1003 in trampoline code Will Deacon
2017-11-30 17:06   ` Robin Murphy
2017-11-30 17:19     ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 15/18] arm64: tls: Avoid unconditional zeroing of tpidrro_el0 for native tasks Will Deacon
2017-11-30 16:39 ` [PATCH v2 16/18] arm64: entry: Add fake CPU feature for unmapping the kernel at EL0 Will Deacon
2017-12-01 13:55   ` Mark Rutland
2017-11-30 16:39 ` [PATCH v2 17/18] arm64: Kconfig: Add CONFIG_UNMAP_KERNEL_AT_EL0 Will Deacon
2017-12-12  8:44   ` Geert Uytterhoeven
2017-12-12 10:28     ` Will Deacon
2017-11-30 16:39 ` Will Deacon [this message]
2017-12-01 12:15   ` [PATCH v2 18/18] perf: arm_spe: Disallow userspace profiling when arm_kernel_unmapped_at_el0() Mark Rutland
2017-12-01 16:49     ` Will Deacon
2017-12-01 16:26   ` Stephen Boyd
2017-12-01 14:04 ` [PATCH v2 00/18] arm64: Unmap the kernel whilst running in userspace (KAISER) Mark Rutland
2017-12-01 17:50   ` Will Deacon
2017-12-01 17:58     ` Mark Rutland
2017-12-01 18:02       ` Dave Hansen
2017-12-01 18:14         ` Will Deacon
2017-12-11  2:24           ` Shanker Donthineni
2017-12-04 23:47 ` Laura Abbott

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1512059986-21325-19-git-send-email-will.deacon@arm.com \
    --to=will.deacon@arm.com \
    --cc=ard.biesheuvel@linaro.org \
    --cc=catalin.marinas@arm.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=keescook@chromium.org \
    --cc=labbott@redhat.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=msalter@redhat.com \
    --cc=sboyd@codeaurora.org \
    --cc=tglx@linutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).