diff --git a/Documentation/arm64/amu.rst b/Documentation/arm64/amu.rst index 5057b11100ed28656893e69c28dd9759092d18f4..036783ee327f252726f645d4684b6673f8a4aad9 100644 --- a/Documentation/arm64/amu.rst +++ b/Documentation/arm64/amu.rst @@ -23,13 +23,14 @@ 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 - clock. - - Instructions retired: increments with every architecturally executed - instruction. - - Memory stall cycles: counts instruction dispatch stall cycles caused by - misses in the last level cache within the clock domain. + +- 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 + instruction. +- 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. @@ -57,11 +58,12 @@ 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 - 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 - from the 'off' power state. + +- 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 + from the 'off' power state. When using kernels that have this feature enabled but boot with broken firmware the user may experience panics or lockups when accessing the @@ -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 - secure mode. - - Purpose: AMU counters are intended for system management use. + +- Security reasons: they might expose information about code executed in + secure mode. +- Purpose: AMU counters are intended for system management use. Also, the presence of the feature is not visible to userspace. @@ -105,8 +109,9 @@ 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 - by other guests or the host. + +- 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 exception being injected into the guest. diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h index 70c47156e54b1791b268fc768166e574ce01625b..c6b4f0603024332948677b9ec9606d201ac32b28 100644 --- a/arch/arm64/include/asm/pointer_auth.h +++ b/arch/arm64/include/asm/pointer_auth.h @@ -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);