Commit 59bff30a authored by Randy Dunlap's avatar Randy Dunlap Committed by Catalin Marinas

Documentation: arm64: fix amu.rst doc warnings

Fix bullet list formatting to eliminate doc warnings:

Documentation/arm64/amu.rst:26: WARNING: Unexpected indentation.
Documentation/arm64/amu.rst:60: WARNING: Unexpected indentation.
Documentation/arm64/amu.rst:81: WARNING: Unexpected indentation.
Documentation/arm64/amu.rst:108: WARNING: Unexpected indentation.
Signed-off-by: default avatarRandy Dunlap <rdunlap@infradead.org>
Cc: Ionela Voinescu <ionela.voinescu@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 3fabb438
......@@ -23,12 +23,13 @@ optional external memory-mapped interface.
Version 1 of the Activity Monitors architecture implements a counter group
of four fixed and architecturally defined 64-bit event counters.
- CPU cycle counter: increments at the frequency of the CPU.
- Constant counter: increments at the fixed frequency of the system
- CPU cycle counter: increments at the frequency of the CPU.
- Constant counter: increments at the fixed frequency of the system
clock.
- Instructions retired: increments with every architecturally executed
- Instructions retired: increments with every architecturally executed
instruction.
- Memory stall cycles: counts instruction dispatch stall cycles caused by
- Memory stall cycles: counts instruction dispatch stall cycles caused by
misses in the last level cache within the clock domain.
When in WFI or WFE these counters do not increment.
......@@ -57,10 +58,11 @@ counters, only the presence of the extension.
Firmware (code running at higher exception levels, e.g. arm-tf) support is
needed to:
- Enable access for lower exception levels (EL2 and EL1) to the AMU
- Enable access for lower exception levels (EL2 and EL1) to the AMU
registers.
- Enable the counters. If not enabled these will read as 0.
- Save/restore the counters before/after the CPU is being put/brought up
- Enable the counters. If not enabled these will read as 0.
- Save/restore the counters before/after the CPU is being put/brought up
from the 'off' power state.
When using kernels that have this feature enabled but boot with broken
......@@ -78,10 +80,11 @@ are not trapped in EL2/EL3.
The fixed counters of AMUv1 are accessible though the following system
register definitions:
- SYS_AMEVCNTR0_CORE_EL0
- SYS_AMEVCNTR0_CONST_EL0
- SYS_AMEVCNTR0_INST_RET_EL0
- SYS_AMEVCNTR0_MEM_STALL_EL0
- SYS_AMEVCNTR0_CORE_EL0
- SYS_AMEVCNTR0_CONST_EL0
- SYS_AMEVCNTR0_INST_RET_EL0
- SYS_AMEVCNTR0_MEM_STALL_EL0
Auxiliary platform specific counters can be accessed using
SYS_AMEVCNTR1_EL0(n), where n is a value between 0 and 15.
......@@ -93,9 +96,10 @@ Userspace access
----------------
Currently, access from userspace to the AMU registers is disabled due to:
- Security reasons: they might expose information about code executed in
- Security reasons: they might expose information about code executed in
secure mode.
- Purpose: AMU counters are intended for system management use.
- Purpose: AMU counters are intended for system management use.
Also, the presence of the feature is not visible to userspace.
......@@ -105,7 +109,8 @@ Virtualization
Currently, access from userspace (EL0) and kernelspace (EL1) on the KVM
guest side is disabled due to:
- Security reasons: they might expose information about code executed
- Security reasons: they might expose information about code executed
by other guests or the host.
Any attempt to access the AMU registers will result in an UNDEFINED
......
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