201698626f
This change introduces a prctl that allows the user program to control which PAC keys are enabled in a particular task. The main reason why this is useful is to enable a userspace ABI that uses PAC to sign and authenticate function pointers and other pointers exposed outside of the function, while still allowing binaries conforming to the ABI to interoperate with legacy binaries that do not sign or authenticate pointers. The idea is that a dynamic loader or early startup code would issue this prctl very early after establishing that a process may load legacy binaries, but before executing any PAC instructions. This change adds a small amount of overhead to kernel entry and exit due to additional required instruction sequences. On a DragonBoard 845c (Cortex-A75) with the powersave governor, the overhead of similar instruction sequences was measured as 4.9ns when simulating the common case where IA is left enabled, or 43.7ns when simulating the uncommon case where IA is disabled. These numbers can be seen as the worst case scenario, since in more realistic scenarios a better performing governor would be used and a newer chip would be used that would support PAC unlike Cortex-A75 and would be expected to be faster than Cortex-A75. On an Apple M1 under a hypervisor, the overhead of the entry/exit instruction sequences introduced by this patch was measured as 0.3ns in the case where IA is left enabled, and 33.0ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://linux-review.googlesource.com/id/Ibc41a5e6a76b275efbaa126b31119dc197b927a5 Link: https://lore.kernel.org/r/d6609065f8f40397a4124654eb68c9f490b4d477.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
160 lines
7.2 KiB
C
160 lines
7.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Based on arch/arm/kernel/asm-offsets.c
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*
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* Copyright (C) 1995-2003 Russell King
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* 2001-2002 Keith Owens
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* Copyright (C) 2012 ARM Ltd.
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*/
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#include <linux/arm_sdei.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/dma-mapping.h>
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#include <linux/kvm_host.h>
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#include <linux/preempt.h>
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#include <linux/suspend.h>
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#include <asm/cpufeature.h>
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#include <asm/fixmap.h>
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#include <asm/thread_info.h>
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#include <asm/memory.h>
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#include <asm/signal32.h>
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#include <asm/smp_plat.h>
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#include <asm/suspend.h>
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#include <linux/kbuild.h>
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#include <linux/arm-smccc.h>
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int main(void)
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{
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DEFINE(TSK_ACTIVE_MM, offsetof(struct task_struct, active_mm));
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BLANK();
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DEFINE(TSK_TI_FLAGS, offsetof(struct task_struct, thread_info.flags));
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DEFINE(TSK_TI_PREEMPT, offsetof(struct task_struct, thread_info.preempt_count));
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#ifdef CONFIG_ARM64_SW_TTBR0_PAN
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DEFINE(TSK_TI_TTBR0, offsetof(struct task_struct, thread_info.ttbr0));
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#endif
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#ifdef CONFIG_SHADOW_CALL_STACK
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DEFINE(TSK_TI_SCS_BASE, offsetof(struct task_struct, thread_info.scs_base));
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DEFINE(TSK_TI_SCS_SP, offsetof(struct task_struct, thread_info.scs_sp));
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#endif
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DEFINE(TSK_STACK, offsetof(struct task_struct, stack));
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#ifdef CONFIG_STACKPROTECTOR
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DEFINE(TSK_STACK_CANARY, offsetof(struct task_struct, stack_canary));
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#endif
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BLANK();
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DEFINE(THREAD_CPU_CONTEXT, offsetof(struct task_struct, thread.cpu_context));
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DEFINE(THREAD_SCTLR_USER, offsetof(struct task_struct, thread.sctlr_user));
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#ifdef CONFIG_ARM64_PTR_AUTH
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DEFINE(THREAD_KEYS_USER, offsetof(struct task_struct, thread.keys_user));
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DEFINE(THREAD_KEYS_KERNEL, offsetof(struct task_struct, thread.keys_kernel));
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#endif
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#ifdef CONFIG_ARM64_MTE
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DEFINE(THREAD_GCR_EL1_USER, offsetof(struct task_struct, thread.gcr_user_excl));
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#endif
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BLANK();
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DEFINE(S_X0, offsetof(struct pt_regs, regs[0]));
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DEFINE(S_X2, offsetof(struct pt_regs, regs[2]));
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DEFINE(S_X4, offsetof(struct pt_regs, regs[4]));
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DEFINE(S_X6, offsetof(struct pt_regs, regs[6]));
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DEFINE(S_X8, offsetof(struct pt_regs, regs[8]));
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DEFINE(S_X10, offsetof(struct pt_regs, regs[10]));
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DEFINE(S_X12, offsetof(struct pt_regs, regs[12]));
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DEFINE(S_X14, offsetof(struct pt_regs, regs[14]));
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DEFINE(S_X16, offsetof(struct pt_regs, regs[16]));
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DEFINE(S_X18, offsetof(struct pt_regs, regs[18]));
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DEFINE(S_X20, offsetof(struct pt_regs, regs[20]));
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DEFINE(S_X22, offsetof(struct pt_regs, regs[22]));
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DEFINE(S_X24, offsetof(struct pt_regs, regs[24]));
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DEFINE(S_X26, offsetof(struct pt_regs, regs[26]));
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DEFINE(S_X28, offsetof(struct pt_regs, regs[28]));
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DEFINE(S_FP, offsetof(struct pt_regs, regs[29]));
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DEFINE(S_LR, offsetof(struct pt_regs, regs[30]));
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DEFINE(S_SP, offsetof(struct pt_regs, sp));
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DEFINE(S_PSTATE, offsetof(struct pt_regs, pstate));
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DEFINE(S_PC, offsetof(struct pt_regs, pc));
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DEFINE(S_SYSCALLNO, offsetof(struct pt_regs, syscallno));
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DEFINE(S_SDEI_TTBR1, offsetof(struct pt_regs, sdei_ttbr1));
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DEFINE(S_PMR_SAVE, offsetof(struct pt_regs, pmr_save));
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DEFINE(S_STACKFRAME, offsetof(struct pt_regs, stackframe));
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DEFINE(PT_REGS_SIZE, sizeof(struct pt_regs));
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BLANK();
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#ifdef CONFIG_COMPAT
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DEFINE(COMPAT_SIGFRAME_REGS_OFFSET, offsetof(struct compat_sigframe, uc.uc_mcontext.arm_r0));
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DEFINE(COMPAT_RT_SIGFRAME_REGS_OFFSET, offsetof(struct compat_rt_sigframe, sig.uc.uc_mcontext.arm_r0));
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BLANK();
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#endif
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DEFINE(MM_CONTEXT_ID, offsetof(struct mm_struct, context.id.counter));
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BLANK();
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DEFINE(VMA_VM_MM, offsetof(struct vm_area_struct, vm_mm));
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DEFINE(VMA_VM_FLAGS, offsetof(struct vm_area_struct, vm_flags));
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BLANK();
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DEFINE(VM_EXEC, VM_EXEC);
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BLANK();
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DEFINE(PAGE_SZ, PAGE_SIZE);
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BLANK();
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DEFINE(DMA_TO_DEVICE, DMA_TO_DEVICE);
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DEFINE(DMA_FROM_DEVICE, DMA_FROM_DEVICE);
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BLANK();
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DEFINE(PREEMPT_DISABLE_OFFSET, PREEMPT_DISABLE_OFFSET);
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BLANK();
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DEFINE(CPU_BOOT_STACK, offsetof(struct secondary_data, stack));
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DEFINE(CPU_BOOT_TASK, offsetof(struct secondary_data, task));
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BLANK();
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DEFINE(FTR_OVR_VAL_OFFSET, offsetof(struct arm64_ftr_override, val));
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DEFINE(FTR_OVR_MASK_OFFSET, offsetof(struct arm64_ftr_override, mask));
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BLANK();
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#ifdef CONFIG_KVM
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DEFINE(VCPU_CONTEXT, offsetof(struct kvm_vcpu, arch.ctxt));
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DEFINE(VCPU_FAULT_DISR, offsetof(struct kvm_vcpu, arch.fault.disr_el1));
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DEFINE(VCPU_WORKAROUND_FLAGS, offsetof(struct kvm_vcpu, arch.workaround_flags));
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DEFINE(VCPU_HCR_EL2, offsetof(struct kvm_vcpu, arch.hcr_el2));
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DEFINE(CPU_USER_PT_REGS, offsetof(struct kvm_cpu_context, regs));
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DEFINE(CPU_APIAKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APIAKEYLO_EL1]));
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DEFINE(CPU_APIBKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APIBKEYLO_EL1]));
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DEFINE(CPU_APDAKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APDAKEYLO_EL1]));
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DEFINE(CPU_APDBKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APDBKEYLO_EL1]));
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DEFINE(CPU_APGAKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APGAKEYLO_EL1]));
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DEFINE(HOST_CONTEXT_VCPU, offsetof(struct kvm_cpu_context, __hyp_running_vcpu));
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DEFINE(HOST_DATA_CONTEXT, offsetof(struct kvm_host_data, host_ctxt));
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DEFINE(NVHE_INIT_MAIR_EL2, offsetof(struct kvm_nvhe_init_params, mair_el2));
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DEFINE(NVHE_INIT_TCR_EL2, offsetof(struct kvm_nvhe_init_params, tcr_el2));
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DEFINE(NVHE_INIT_TPIDR_EL2, offsetof(struct kvm_nvhe_init_params, tpidr_el2));
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DEFINE(NVHE_INIT_STACK_HYP_VA, offsetof(struct kvm_nvhe_init_params, stack_hyp_va));
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DEFINE(NVHE_INIT_PGD_PA, offsetof(struct kvm_nvhe_init_params, pgd_pa));
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#endif
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#ifdef CONFIG_CPU_PM
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DEFINE(CPU_CTX_SP, offsetof(struct cpu_suspend_ctx, sp));
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DEFINE(MPIDR_HASH_MASK, offsetof(struct mpidr_hash, mask));
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DEFINE(MPIDR_HASH_SHIFTS, offsetof(struct mpidr_hash, shift_aff));
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DEFINE(SLEEP_STACK_DATA_SYSTEM_REGS, offsetof(struct sleep_stack_data, system_regs));
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DEFINE(SLEEP_STACK_DATA_CALLEE_REGS, offsetof(struct sleep_stack_data, callee_saved_regs));
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#endif
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DEFINE(ARM_SMCCC_RES_X0_OFFS, offsetof(struct arm_smccc_res, a0));
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DEFINE(ARM_SMCCC_RES_X2_OFFS, offsetof(struct arm_smccc_res, a2));
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DEFINE(ARM_SMCCC_QUIRK_ID_OFFS, offsetof(struct arm_smccc_quirk, id));
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DEFINE(ARM_SMCCC_QUIRK_STATE_OFFS, offsetof(struct arm_smccc_quirk, state));
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BLANK();
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DEFINE(HIBERN_PBE_ORIG, offsetof(struct pbe, orig_address));
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DEFINE(HIBERN_PBE_ADDR, offsetof(struct pbe, address));
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DEFINE(HIBERN_PBE_NEXT, offsetof(struct pbe, next));
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DEFINE(ARM64_FTR_SYSVAL, offsetof(struct arm64_ftr_reg, sys_val));
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BLANK();
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#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
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DEFINE(TRAMP_VALIAS, TRAMP_VALIAS);
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#endif
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#ifdef CONFIG_ARM_SDE_INTERFACE
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DEFINE(SDEI_EVENT_INTREGS, offsetof(struct sdei_registered_event, interrupted_regs));
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DEFINE(SDEI_EVENT_PRIORITY, offsetof(struct sdei_registered_event, priority));
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#endif
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#ifdef CONFIG_ARM64_PTR_AUTH
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DEFINE(PTRAUTH_USER_KEY_APIA, offsetof(struct ptrauth_keys_user, apia));
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DEFINE(PTRAUTH_USER_KEY_APIB, offsetof(struct ptrauth_keys_user, apib));
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DEFINE(PTRAUTH_USER_KEY_APDA, offsetof(struct ptrauth_keys_user, apda));
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DEFINE(PTRAUTH_USER_KEY_APDB, offsetof(struct ptrauth_keys_user, apdb));
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DEFINE(PTRAUTH_USER_KEY_APGA, offsetof(struct ptrauth_keys_user, apga));
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DEFINE(PTRAUTH_KERNEL_KEY_APIA, offsetof(struct ptrauth_keys_kernel, apia));
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BLANK();
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#endif
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return 0;
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}
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