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Diffstat (limited to 'Documentation/admin-guide/sysctl/kernel.rst')
| -rw-r--r-- | Documentation/admin-guide/sysctl/kernel.rst | 36 |
1 files changed, 16 insertions, 20 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index dd49a89a62d3..c04e6b8eb2b1 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -1014,30 +1014,26 @@ perf_user_access (arm64 and riscv only) Controls user space access for reading perf event counters. -arm64 -===== - -The default value is 0 (access disabled). +* for arm64 + The default value is 0 (access disabled). -When set to 1, user space can read performance monitor counter registers -directly. + When set to 1, user space can read performance monitor counter registers + directly. -See Documentation/arch/arm64/perf.rst for more information. - -riscv -===== + See Documentation/arch/arm64/perf.rst for more information. -When set to 0, user space access is disabled. +* for riscv + When set to 0, user space access is disabled. -The default value is 1, user space can read performance monitor counter -registers through perf, any direct access without perf intervention will trigger -an illegal instruction. + The default value is 1, user space can read performance monitor counter + registers through perf, any direct access without perf intervention will trigger + an illegal instruction. -When set to 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 user space applications are fixed. + When set to 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 user space applications are fixed. -Note that the time CSR is always directly accessible to all modes. + Note that the time CSR is always directly accessible to all modes. pid_max ======= @@ -1465,7 +1461,7 @@ stack_erasing ============= This parameter can be used to control kernel stack erasing at the end -of syscalls for kernels built with ``CONFIG_GCC_PLUGIN_STACKLEAK``. +of syscalls for kernels built with ``CONFIG_KSTACK_ERASE``. That erasing reduces the information which kernel stack leak bugs can reveal and blocks some uninitialized stack variable attacks. @@ -1473,7 +1469,7 @@ The tradeoff is the performance impact: on a single CPU system kernel compilation sees a 1% slowdown, other systems and workloads may vary. = ==================================================================== -0 Kernel stack erasing is disabled, STACKLEAK_METRICS are not updated. +0 Kernel stack erasing is disabled, KSTACK_ERASE_METRICS are not updated. 1 Kernel stack erasing is enabled (default), it is performed before returning to the userspace at the end of syscalls. = ==================================================================== |