From 2bc6b218717b9d08f466f88209251d54bc09b207 Mon Sep 17 00:00:00 2001 From: Fuad Tabba Date: Tue, 22 Sep 2026 19:14:30 +0100 Subject: arm64/boot: Disable trapping of PMZR_EL0 writes to EL2 __init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2. PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a write from EL0 reaches the trap and takes the host down without a panic message. Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9 bits. Fixes: 858c7bfcb35e1 ("arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9") Cc: stable@vger.kernel.org Signed-off-by: Fuad Tabba Reviewed-by: Anshuman Khandual Reviewed-by: Oliver Upton Signed-off-by: Will Deacon --- Documentation/admin-guide/sysctl/abi.rst | 34 ++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 Documentation/admin-guide/sysctl/abi.rst (limited to 'Documentation/admin-guide/sysctl/abi.rst') diff --git a/Documentation/admin-guide/sysctl/abi.rst b/Documentation/admin-guide/sysctl/abi.rst new file mode 100644 index 000000000..4e6db0a2a --- /dev/null +++ b/Documentation/admin-guide/sysctl/abi.rst @@ -0,0 +1,34 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +================================ +Documentation for /proc/sys/abi/ +================================ + +.. See scripts/check-sysctl-docs to keep this up to date: +.. scripts/check-sysctl-docs -vtable="abi" \ +.. Documentation/admin-guide/sysctl/abi.rst \ +.. $(git grep -l register_sysctl_) + +Copyright (c) 2020, Stephen Kitt + +For general info, see Documentation/admin-guide/sysctl/index.rst. + +------------------------------------------------------------------------------ + +The files in ``/proc/sys/abi`` can be used to see and modify +ABI-related settings. + +Currently, these files might (depending on your configuration) +show up in ``/proc/sys/kernel``: + +.. contents:: :local: + +vsyscall32 (x86) +================ + +Determines whether the kernels maps a vDSO page into 32-bit processes; +can be set to 1 to enable, or 0 to disable. Defaults to enabled if +``CONFIG_COMPAT_VDSO`` is set, disabled otherwise. + +This controls the same setting as the ``vdso32`` kernel boot +parameter. -- cgit v1.3.1