diff options
Diffstat (limited to 'arch/arm64/kernel/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 196 |
1 files changed, 109 insertions, 87 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index ddcde093c433..55af8b504b65 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -15,6 +15,7 @@ #include <asm/assembler.h> #include <asm/asm-offsets.h> #include <asm/asm_pointer_auth.h> +#include <asm/bug.h> #include <asm/cpufeature.h> #include <asm/errno.h> #include <asm/esr.h> @@ -23,6 +24,7 @@ #include <asm/mmu.h> #include <asm/processor.h> #include <asm/ptrace.h> +#include <asm/scs.h> #include <asm/thread_info.h> #include <asm/asm-uaccess.h> #include <asm/unistd.h> @@ -125,8 +127,10 @@ alternative_else_nop_endif add \dst, \dst, #(\sym - .entry.tramp.text) .endm - // This macro corrupts x0-x3. It is the caller's duty - // to save/restore them if required. + /* + * This macro corrupts x0-x3. It is the caller's duty to save/restore + * them if required. + */ .macro apply_ssbd, state, tmp1, tmp2 #ifdef CONFIG_ARM64_SSBD alternative_cb arm64_enable_wa2_handling @@ -171,14 +175,18 @@ alternative_cb_end ldr_this_cpu tsk, __entry_task, x20 msr sp_el0, tsk - // Ensure MDSCR_EL1.SS is clear, since we can unmask debug exceptions - // when scheduling. + /* + * Ensure MDSCR_EL1.SS is clear, since we can unmask debug exceptions + * when scheduling. + */ ldr x19, [tsk, #TSK_TI_FLAGS] disable_step_tsk x19, x20 apply_ssbd 1, x22, x23 - ptrauth_keys_install_kernel tsk, 1, x20, x22, x23 + ptrauth_keys_install_kernel tsk, x20, x22, x23 + + scs_load tsk, x20 .else add x21, sp, #S_FRAME_SIZE get_current_task tsk @@ -206,28 +214,9 @@ alternative_cb_end add x29, sp, #S_STACKFRAME #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_if_not ARM64_HAS_PAN + bl __swpan_entry_el\el alternative_else_nop_endif - - .if \el != 0 - mrs x21, ttbr0_el1 - tst x21, #TTBR_ASID_MASK // 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] @@ -281,34 +270,9 @@ alternative_else_nop_endif .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_if_not ARM64_HAS_PAN + bl __swpan_exit_el\el 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, x1 - - .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). - */ - bl post_ttbr_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 @@ -328,21 +292,8 @@ alternative_if ARM64_WORKAROUND_845719 alternative_else_nop_endif #endif 3: -#ifdef CONFIG_ARM64_ERRATUM_1418040 -alternative_if_not ARM64_WORKAROUND_1418040 - b 4f -alternative_else_nop_endif - /* - * if (x22.mode32 == cntkctl_el1.el0vcten) - * cntkctl_el1.el0vcten = ~cntkctl_el1.el0vcten - */ - mrs x1, cntkctl_el1 - eon x0, x1, x22, lsr #3 - tbz x0, #1, 4f - eor x1, x1, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN - msr cntkctl_el1, x1 -4: -#endif + scs_save tsk, x0 + /* No kernel C function calls after this as user keys are set. */ ptrauth_keys_install_user tsk, x0, x1, x2 @@ -372,11 +323,11 @@ alternative_else_nop_endif .if \el == 0 alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 - bne 5f + bne 4f msr far_el1, x30 tramp_alias x30, tramp_exit_native br x30 -5: +4: tramp_alias x30, tramp_exit_compat br x30 #endif @@ -386,8 +337,54 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 sb .endm +#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. + */ +SYM_CODE_START_LOCAL(__swpan_entry_el1) + mrs x21, ttbr0_el1 + tst x21, #TTBR_ASID_MASK // 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 +SYM_INNER_LABEL(__swpan_entry_el0, SYM_L_LOCAL) + __uaccess_ttbr0_disable x21 +1: ret +SYM_CODE_END(__swpan_entry_el1) + + /* + * Restore access to TTBR0_EL1. If returning to EL0, no need for SPSR + * PAN bit checking. + */ +SYM_CODE_START_LOCAL(__swpan_exit_el1) + tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set + __uaccess_ttbr0_enable x0, x1 +1: and x22, x22, #~PSR_PAN_BIT // ARMv8.0 CPUs do not understand this bit + ret +SYM_CODE_END(__swpan_exit_el1) + +SYM_CODE_START_LOCAL(__swpan_exit_el0) + __uaccess_ttbr0_enable x0, x1 + /* + * 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). + */ + b post_ttbr_update_workaround +SYM_CODE_END(__swpan_exit_el0) +#endif + .macro irq_stack_entry mov x19, sp // preserve the original sp +#ifdef CONFIG_SHADOW_CALL_STACK + mov x24, scs_sp // preserve the original shadow stack +#endif /* * Compare sp with the base of the task stack. @@ -405,15 +402,25 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 /* switch to the irq stack */ mov sp, x26 + +#ifdef CONFIG_SHADOW_CALL_STACK + /* also switch to the irq shadow stack */ + adr_this_cpu scs_sp, irq_shadow_call_stack, x26 +#endif + 9998: .endm /* - * x19 should be preserved between irq_stack_entry and - * irq_stack_exit. + * The callee-saved regs (x19-x29) should be preserved between + * irq_stack_entry and irq_stack_exit, but note that kernel_entry + * uses x20-x23 to store data for later use. */ .macro irq_stack_exit mov sp, x19 +#ifdef CONFIG_SHADOW_CALL_STACK + mov scs_sp, x24 +#endif .endm /* GPRs used by entry code */ @@ -728,20 +735,9 @@ el0_error_naked: SYM_CODE_END(el0_error) /* - * Ok, we need to do extra processing, enter the slow path. - */ -work_pending: - mov x0, sp // 'regs' - bl do_notify_resume -#ifdef CONFIG_TRACE_IRQFLAGS - bl trace_hardirqs_on // enabled while in userspace -#endif - ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for single-step - b finish_ret_to_user -/* * "slow" syscall return path. */ -ret_to_user: +SYM_CODE_START_LOCAL(ret_to_user) disable_daif gic_prio_kentry_setup tmp=x3 ldr x1, [tsk, #TSK_TI_FLAGS] @@ -753,7 +749,19 @@ finish_ret_to_user: bl stackleak_erase #endif kernel_exit 0 -ENDPROC(ret_to_user) + +/* + * Ok, we need to do extra processing, enter the slow path. + */ +work_pending: + mov x0, sp // 'regs' + bl do_notify_resume +#ifdef CONFIG_TRACE_IRQFLAGS + bl trace_hardirqs_on // enabled while in userspace +#endif + ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for single-step + b finish_ret_to_user +SYM_CODE_END(ret_to_user) .popsection // .entry.text @@ -900,7 +908,9 @@ SYM_FUNC_START(cpu_switch_to) ldr lr, [x8] mov sp, x9 msr sp_el0, x1 - ptrauth_keys_install_kernel x1, 1, x8, x9, x10 + ptrauth_keys_install_kernel x1, x8, x9, x10 + scs_save x0, x8 + scs_load x1, x8 ret SYM_FUNC_END(cpu_switch_to) NOKPROBE(cpu_switch_to) @@ -1029,13 +1039,16 @@ SYM_CODE_START(__sdei_asm_handler) mov x19, x1 +#if defined(CONFIG_VMAP_STACK) || defined(CONFIG_SHADOW_CALL_STACK) + ldrb w4, [x19, #SDEI_EVENT_PRIORITY] +#endif + #ifdef CONFIG_VMAP_STACK /* * entry.S may have been using sp as a scratch register, find whether * this is a normal or critical event and switch to the appropriate * stack for this CPU. */ - ldrb w4, [x19, #SDEI_EVENT_PRIORITY] cbnz w4, 1f ldr_this_cpu dst=x5, sym=sdei_stack_normal_ptr, tmp=x6 b 2f @@ -1045,6 +1058,15 @@ SYM_CODE_START(__sdei_asm_handler) mov sp, x5 #endif +#ifdef CONFIG_SHADOW_CALL_STACK + /* Use a separate shadow call stack for normal and critical events */ + cbnz w4, 3f + adr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal, tmp=x6 + b 4f +3: adr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical, tmp=x6 +4: +#endif + /* * We may have interrupted userspace, or a guest, or exit-from or * return-to either of these. We can't trust sp_el0, restore it. |