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3c2483f154
When KVM injects an exception into a guest, it generates the CPSR value
from scratch, configuring CPSR.{M,A,I,T,E}, and setting all other
bits to zero.
This isn't correct, as the architecture specifies that some CPSR bits
are (conditionally) cleared or set upon an exception, and others are
unchanged from the original context.
This patch adds logic to match the architectural behaviour. To make this
simple to follow/audit/extend, documentation references are provided,
and bits are configured in order of their layout in SPSR_EL2. This
layout can be seen in the diagram on ARM DDI 0487E.a page C5-426.
Note that this code is used by both arm and arm64, and is intended to
fuction with the SPSR_EL2 and SPSR_HYP layouts.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200108134324.46500-3-mark.rutland@arm.com
362 lines
9.4 KiB
C
362 lines
9.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Based on arch/arm/include/asm/ptrace.h
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*
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* Copyright (C) 1996-2003 Russell King
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* Copyright (C) 2012 ARM Ltd.
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*/
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#ifndef __ASM_PTRACE_H
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#define __ASM_PTRACE_H
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#include <asm/cpufeature.h>
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#include <uapi/asm/ptrace.h>
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/* Current Exception Level values, as contained in CurrentEL */
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#define CurrentEL_EL1 (1 << 2)
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#define CurrentEL_EL2 (2 << 2)
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/*
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* PMR values used to mask/unmask interrupts.
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*
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* GIC priority masking works as follows: if an IRQ's priority is a higher value
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* than the value held in PMR, that IRQ is masked. Lowering the value of PMR
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* means masking more IRQs (or at least that the same IRQs remain masked).
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*
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* To mask interrupts, we clear the most significant bit of PMR.
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*
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* Some code sections either automatically switch back to PSR.I or explicitly
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* require to not use priority masking. If bit GIC_PRIO_PSR_I_SET is included
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* in the the priority mask, it indicates that PSR.I should be set and
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* interrupt disabling temporarily does not rely on IRQ priorities.
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*/
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#define GIC_PRIO_IRQON 0xe0
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#define GIC_PRIO_IRQOFF (GIC_PRIO_IRQON & ~0x80)
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#define GIC_PRIO_PSR_I_SET (1 << 4)
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/* Additional SPSR bits not exposed in the UABI */
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#define PSR_IL_BIT (1 << 20)
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/* AArch32-specific ptrace requests */
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#define COMPAT_PTRACE_GETREGS 12
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#define COMPAT_PTRACE_SETREGS 13
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#define COMPAT_PTRACE_GET_THREAD_AREA 22
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#define COMPAT_PTRACE_SET_SYSCALL 23
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#define COMPAT_PTRACE_GETVFPREGS 27
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#define COMPAT_PTRACE_SETVFPREGS 28
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#define COMPAT_PTRACE_GETHBPREGS 29
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#define COMPAT_PTRACE_SETHBPREGS 30
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/* SPSR_ELx bits for exceptions taken from AArch32 */
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#define PSR_AA32_MODE_MASK 0x0000001f
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#define PSR_AA32_MODE_USR 0x00000010
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#define PSR_AA32_MODE_FIQ 0x00000011
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#define PSR_AA32_MODE_IRQ 0x00000012
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#define PSR_AA32_MODE_SVC 0x00000013
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#define PSR_AA32_MODE_ABT 0x00000017
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#define PSR_AA32_MODE_HYP 0x0000001a
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#define PSR_AA32_MODE_UND 0x0000001b
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#define PSR_AA32_MODE_SYS 0x0000001f
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#define PSR_AA32_T_BIT 0x00000020
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#define PSR_AA32_F_BIT 0x00000040
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#define PSR_AA32_I_BIT 0x00000080
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#define PSR_AA32_A_BIT 0x00000100
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#define PSR_AA32_E_BIT 0x00000200
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#define PSR_AA32_PAN_BIT 0x00400000
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#define PSR_AA32_SSBS_BIT 0x00800000
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#define PSR_AA32_DIT_BIT 0x01000000
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#define PSR_AA32_Q_BIT 0x08000000
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#define PSR_AA32_V_BIT 0x10000000
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#define PSR_AA32_C_BIT 0x20000000
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#define PSR_AA32_Z_BIT 0x40000000
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#define PSR_AA32_N_BIT 0x80000000
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#define PSR_AA32_IT_MASK 0x0600fc00 /* If-Then execution state mask */
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#define PSR_AA32_GE_MASK 0x000f0000
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#ifdef CONFIG_CPU_BIG_ENDIAN
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#define PSR_AA32_ENDSTATE PSR_AA32_E_BIT
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#else
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#define PSR_AA32_ENDSTATE 0
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#endif
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/* AArch32 CPSR bits, as seen in AArch32 */
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#define COMPAT_PSR_DIT_BIT 0x00200000
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/*
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* These are 'magic' values for PTRACE_PEEKUSR that return info about where a
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* process is located in memory.
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*/
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#define COMPAT_PT_TEXT_ADDR 0x10000
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#define COMPAT_PT_DATA_ADDR 0x10004
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#define COMPAT_PT_TEXT_END_ADDR 0x10008
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/*
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* If pt_regs.syscallno == NO_SYSCALL, then the thread is not executing
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* a syscall -- i.e., its most recent entry into the kernel from
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* userspace was not via SVC, or otherwise a tracer cancelled the syscall.
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*
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* This must have the value -1, for ABI compatibility with ptrace etc.
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*/
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#define NO_SYSCALL (-1)
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#ifndef __ASSEMBLY__
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#include <linux/bug.h>
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#include <linux/types.h>
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/* sizeof(struct user) for AArch32 */
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#define COMPAT_USER_SZ 296
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/* Architecturally defined mapping between AArch32 and AArch64 registers */
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#define compat_usr(x) regs[(x)]
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#define compat_fp regs[11]
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#define compat_sp regs[13]
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#define compat_lr regs[14]
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#define compat_sp_hyp regs[15]
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#define compat_lr_irq regs[16]
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#define compat_sp_irq regs[17]
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#define compat_lr_svc regs[18]
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#define compat_sp_svc regs[19]
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#define compat_lr_abt regs[20]
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#define compat_sp_abt regs[21]
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#define compat_lr_und regs[22]
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#define compat_sp_und regs[23]
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#define compat_r8_fiq regs[24]
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#define compat_r9_fiq regs[25]
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#define compat_r10_fiq regs[26]
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#define compat_r11_fiq regs[27]
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#define compat_r12_fiq regs[28]
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#define compat_sp_fiq regs[29]
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#define compat_lr_fiq regs[30]
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static inline unsigned long compat_psr_to_pstate(const unsigned long psr)
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{
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unsigned long pstate;
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pstate = psr & ~COMPAT_PSR_DIT_BIT;
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if (psr & COMPAT_PSR_DIT_BIT)
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pstate |= PSR_AA32_DIT_BIT;
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return pstate;
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}
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static inline unsigned long pstate_to_compat_psr(const unsigned long pstate)
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{
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unsigned long psr;
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psr = pstate & ~PSR_AA32_DIT_BIT;
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if (pstate & PSR_AA32_DIT_BIT)
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psr |= COMPAT_PSR_DIT_BIT;
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return psr;
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}
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/*
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* This struct defines the way the registers are stored on the stack during an
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* exception. Note that sizeof(struct pt_regs) has to be a multiple of 16 (for
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* stack alignment). struct user_pt_regs must form a prefix of struct pt_regs.
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*/
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struct pt_regs {
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union {
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struct user_pt_regs user_regs;
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struct {
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u64 regs[31];
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u64 sp;
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u64 pc;
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u64 pstate;
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};
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};
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u64 orig_x0;
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#ifdef __AARCH64EB__
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u32 unused2;
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s32 syscallno;
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#else
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s32 syscallno;
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u32 unused2;
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#endif
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u64 orig_addr_limit;
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/* Only valid when ARM64_HAS_IRQ_PRIO_MASKING is enabled. */
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u64 pmr_save;
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u64 stackframe[2];
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};
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static inline bool in_syscall(struct pt_regs const *regs)
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{
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return regs->syscallno != NO_SYSCALL;
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}
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static inline void forget_syscall(struct pt_regs *regs)
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{
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regs->syscallno = NO_SYSCALL;
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}
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#define MAX_REG_OFFSET offsetof(struct pt_regs, pstate)
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#define arch_has_single_step() (1)
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#ifdef CONFIG_COMPAT
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#define compat_thumb_mode(regs) \
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(((regs)->pstate & PSR_AA32_T_BIT))
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#else
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#define compat_thumb_mode(regs) (0)
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#endif
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#define user_mode(regs) \
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(((regs)->pstate & PSR_MODE_MASK) == PSR_MODE_EL0t)
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#define compat_user_mode(regs) \
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(((regs)->pstate & (PSR_MODE32_BIT | PSR_MODE_MASK)) == \
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(PSR_MODE32_BIT | PSR_MODE_EL0t))
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#define processor_mode(regs) \
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((regs)->pstate & PSR_MODE_MASK)
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#define irqs_priority_unmasked(regs) \
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(system_uses_irq_prio_masking() ? \
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(regs)->pmr_save == GIC_PRIO_IRQON : \
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true)
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#define interrupts_enabled(regs) \
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(!((regs)->pstate & PSR_I_BIT) && irqs_priority_unmasked(regs))
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#define fast_interrupts_enabled(regs) \
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(!((regs)->pstate & PSR_F_BIT))
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static inline unsigned long user_stack_pointer(struct pt_regs *regs)
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{
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if (compat_user_mode(regs))
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return regs->compat_sp;
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return regs->sp;
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}
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extern int regs_query_register_offset(const char *name);
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extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
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unsigned int n);
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/**
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* regs_get_register() - get register value from its offset
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* @regs: pt_regs from which register value is gotten
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* @offset: offset of the register.
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*
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* regs_get_register returns the value of a register whose offset from @regs.
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* The @offset is the offset of the register in struct pt_regs.
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* If @offset is bigger than MAX_REG_OFFSET, this returns 0.
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*/
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static inline u64 regs_get_register(struct pt_regs *regs, unsigned int offset)
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{
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u64 val = 0;
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WARN_ON(offset & 7);
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offset >>= 3;
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switch (offset) {
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case 0 ... 30:
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val = regs->regs[offset];
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break;
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case offsetof(struct pt_regs, sp) >> 3:
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val = regs->sp;
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break;
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case offsetof(struct pt_regs, pc) >> 3:
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val = regs->pc;
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break;
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case offsetof(struct pt_regs, pstate) >> 3:
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val = regs->pstate;
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break;
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default:
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val = 0;
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}
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return val;
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}
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/*
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* Read a register given an architectural register index r.
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* This handles the common case where 31 means XZR, not SP.
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*/
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static inline unsigned long pt_regs_read_reg(const struct pt_regs *regs, int r)
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{
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return (r == 31) ? 0 : regs->regs[r];
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}
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/*
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* Write a register given an architectural register index r.
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* This handles the common case where 31 means XZR, not SP.
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*/
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static inline void pt_regs_write_reg(struct pt_regs *regs, int r,
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unsigned long val)
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{
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if (r != 31)
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regs->regs[r] = val;
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}
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/* Valid only for Kernel mode traps. */
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static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
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{
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return regs->sp;
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}
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static inline unsigned long regs_return_value(struct pt_regs *regs)
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{
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return regs->regs[0];
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}
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static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
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{
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regs->regs[0] = rc;
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}
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/**
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* regs_get_kernel_argument() - get Nth function argument in kernel
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* @regs: pt_regs of that context
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* @n: function argument number (start from 0)
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*
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* regs_get_argument() returns @n th argument of the function call.
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*
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* Note that this chooses the most likely register mapping. In very rare
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* cases this may not return correct data, for example, if one of the
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* function parameters is 16 bytes or bigger. In such cases, we cannot
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* get access the parameter correctly and the register assignment of
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* subsequent parameters will be shifted.
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*/
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static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
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unsigned int n)
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{
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#define NR_REG_ARGUMENTS 8
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if (n < NR_REG_ARGUMENTS)
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return pt_regs_read_reg(regs, n);
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return 0;
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}
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/* We must avoid circular header include via sched.h */
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struct task_struct;
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int valid_user_regs(struct user_pt_regs *regs, struct task_struct *task);
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static inline unsigned long instruction_pointer(struct pt_regs *regs)
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{
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return regs->pc;
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}
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static inline void instruction_pointer_set(struct pt_regs *regs,
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unsigned long val)
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{
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regs->pc = val;
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}
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static inline unsigned long frame_pointer(struct pt_regs *regs)
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{
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return regs->regs[29];
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}
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#define procedure_link_pointer(regs) ((regs)->regs[30])
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static inline void procedure_link_pointer_set(struct pt_regs *regs,
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unsigned long val)
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{
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procedure_link_pointer(regs) = val;
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}
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extern unsigned long profile_pc(struct pt_regs *regs);
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#endif /* __ASSEMBLY__ */
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#endif
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