[PATCH v3 08/10] Documentation: admin-guide: Add riscv sysctl_perf_user_access
From: Alexandre Ghiti <hidden>
Date: 2023-06-30 08:40:24
Also in:
linux-doc, linux-perf-users, linux-riscv, lkml
Subsystem:
documentation, the rest · Maintainers:
Jonathan Corbet, Linus Torvalds
riscv now uses this sysctl so document its usage for this architecture. Signed-off-by: Alexandre Ghiti <redacted> --- Documentation/admin-guide/sysctl/kernel.rst | 26 +++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index d85d90f5d000..c376692b372b 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst@@ -941,16 +941,34 @@ enabled, otherwise writing to this file will return ``-EBUSY``. The default value is 8. -perf_user_access (arm64 only) -================================= +perf_user_access (arm64 and riscv only) +======================================= + +Controls user space access for reading perf event counters. -Controls user space access for reading perf event counters. When set to 1, -user space can read performance monitor counter registers directly. +arm64 +===== The default value is 0 (access disabled). +When set to 1, user space can read performance monitor counter registers +directly. See Documentation/arm64/perf.rst for more information. +riscv +===== + +When set to 0, user access is disabled. + +When set to 1, user space can read performance monitor counter registers +directly only through perf, any direct access without perf intervention will +trigger an illegal instruction. + +The default value is 2, which enables legacy mode (user space has direct +access to cycle and insret CSRs only). Note that this legacy value +is deprecated and will be removed once all userspace applications are fixed. + +Note that the time CSR is for now always accessible to all modes. pid_max =======
--
2.39.2
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