diff options
Diffstat (limited to 'arch/arm64/kernel/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index b7db3766a312..4f0d76339414 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -29,7 +29,9 @@ #include <asm/esr.h> #include <asm/irq.h> #include <asm/memory.h> +#include <asm/ptrace.h> #include <asm/thread_info.h> +#include <asm/uaccess.h> #include <asm/unistd.h> /* @@ -108,6 +110,32 @@ mrs x22, elr_el1 mrs x23, spsr_el1 stp lr, x21, [sp, #S_LR] + +#ifdef CONFIG_ARM64_SW_TTBR0_PAN + /* + * Set the TTBR0 PAN bit in SPSR. When the exception is taken from + * EL0, there is no need to check the state of TTBR0_EL1 since + * accesses are always enabled. + * Note that the meaning of this bit differs from the ARMv8.1 PAN + * feature as all TTBR0_EL1 accesses are disabled, not just those to + * user mappings. + */ +alternative_if ARM64_HAS_PAN + b 1f // skip TTBR0 PAN +alternative_else_nop_endif + + .if \el != 0 + mrs x21, ttbr0_el1 + tst x21, #0xffff << 48 // Check for the reserved ASID + orr x23, x23, #PSR_PAN_BIT // Set the emulated PAN in the saved SPSR + b.eq 1f // TTBR0 access already disabled + and x23, x23, #~PSR_PAN_BIT // Clear the emulated PAN in the saved SPSR + .endif + + __uaccess_ttbr0_disable x21 +1: +#endif + stp x22, x23, [sp, #S_PC] /* @@ -146,6 +174,40 @@ ldp x21, x22, [sp, #S_PC] // load ELR, SPSR .if \el == 0 ct_user_enter + .endif + +#ifdef CONFIG_ARM64_SW_TTBR0_PAN + /* + * Restore access to TTBR0_EL1. If returning to EL0, no need for SPSR + * PAN bit checking. + */ +alternative_if ARM64_HAS_PAN + b 2f // skip TTBR0 PAN +alternative_else_nop_endif + + .if \el != 0 + tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set + .endif + + __uaccess_ttbr0_enable x0 + + .if \el == 0 + /* + * Enable errata workarounds only if returning to user. The only + * workaround currently required for TTBR0_EL1 changes are for the + * Cavium erratum 27456 (broadcast TLBI instructions may cause I-cache + * corruption). + */ + post_ttbr0_update_workaround + .endif +1: + .if \el != 0 + and x22, x22, #~PSR_PAN_BIT // ARMv8.0 CPUs do not understand this bit + .endif +2: +#endif + + .if \el == 0 ldr x23, [sp, #S_SP] // load return stack pointer msr sp_el0, x23 #ifdef CONFIG_ARM64_ERRATUM_845719 @@ -161,6 +223,7 @@ alternative_if ARM64_WORKAROUND_845719 alternative_else_nop_endif #endif .endif + msr elr_el1, x21 // set up the return data msr spsr_el1, x22 ldp x0, x1, [sp, #16 * 0] |