- Ensure context synchronisation after a write to APIAKey.

- Fix bullet list formatting in Documentation/arm64/amu.rst to eliminate
   doc warnings.
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Catalin Marinas:

 - Ensure context synchronisation after a write to APIAKey.

 - Fix bullet list formatting in Documentation/arm64/amu.rst to
   eliminate doc warnings.

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  Documentation: arm64: fix amu.rst doc warnings
  arm64: sync kernel APIAKey when installing
This commit is contained in:
Linus Torvalds 2020-04-24 11:34:43 -07:00
commit 4544db3f84
2 changed files with 32 additions and 24 deletions

View File

@ -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

View File

@ -47,7 +47,7 @@ static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
get_random_bytes(&keys->apga, sizeof(keys->apga));
}
#define __ptrauth_key_install(k, v) \
#define __ptrauth_key_install_nosync(k, v) \
do { \
struct ptrauth_key __pki_v = (v); \
write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1); \
@ -62,8 +62,11 @@ static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel
static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
{
if (system_supports_address_auth())
__ptrauth_key_install(APIA, keys->apia);
if (!system_supports_address_auth())
return;
__ptrauth_key_install_nosync(APIA, keys->apia);
isb();
}
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);