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linux/arch/arm/include/asm/assembler.h
Russell King 8bafae202c ARM: BUG if jumping to usermode address in kernel mode 
Detect if we are returning to usermode via the normal kernel exit paths
but the saved PSR value indicates that we are in kernel mode.  This
could occur due to corrupted stack state, which has been observed with
"ftracetest".

This ensures that we catch the problem case before we get to user code.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2017-11-26 15:41:39 +00:00

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/*
* arch/arm/include/asm/assembler.h
*
* Copyright (C) 1996-2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This file contains arm architecture specific defines
* for the different processors.
*
* Do not include any C declarations in this file - it is included by
* assembler source.
*/
#ifndef __ASM_ASSEMBLER_H__
#define __ASM_ASSEMBLER_H__
#ifndef __ASSEMBLY__
#error "Only include this from assembly code"
#endif
#include <asm/ptrace.h>
#include <asm/domain.h>
#include <asm/opcodes-virt.h>
#include <asm/asm-offsets.h>
#include <asm/page.h>
#include <asm/thread_info.h>
#define IOMEM(x) (x)
/*
* Endian independent macros for shifting bytes within registers.
*/
#ifndef __ARMEB__
#define lspull lsr
#define lspush lsl
#define get_byte_0 lsl #0
#define get_byte_1 lsr #8
#define get_byte_2 lsr #16
#define get_byte_3 lsr #24
#define put_byte_0 lsl #0
#define put_byte_1 lsl #8
#define put_byte_2 lsl #16
#define put_byte_3 lsl #24
#else
#define lspull lsl
#define lspush lsr
#define get_byte_0 lsr #24
#define get_byte_1 lsr #16
#define get_byte_2 lsr #8
#define get_byte_3 lsl #0
#define put_byte_0 lsl #24
#define put_byte_1 lsl #16
#define put_byte_2 lsl #8
#define put_byte_3 lsl #0
#endif
/* Select code for any configuration running in BE8 mode */
#ifdef CONFIG_CPU_ENDIAN_BE8
#define ARM_BE8(code...) code
#else
#define ARM_BE8(code...)
#endif
/*
* Data preload for architectures that support it
*/
#if __LINUX_ARM_ARCH__ >= 5
#define PLD(code...) code
#else
#define PLD(code...)
#endif
/*
* This can be used to enable code to cacheline align the destination
* pointer when bulk writing to memory. Experiments on StrongARM and
* XScale didn't show this a worthwhile thing to do when the cache is not
* set to write-allocate (this would need further testing on XScale when WA
* is used).
*
* On Feroceon there is much to gain however, regardless of cache mode.
*/
#ifdef CONFIG_CPU_FEROCEON
#define CALGN(code...) code
#else
#define CALGN(code...)
#endif
#define IMM12_MASK 0xfff
/*
* Enable and disable interrupts
*/
#if __LINUX_ARM_ARCH__ >= 6
.macro disable_irq_notrace
cpsid i
.endm
.macro enable_irq_notrace
cpsie i
.endm
#else
.macro disable_irq_notrace
msr cpsr_c, #PSR_I_BIT | SVC_MODE
.endm
.macro enable_irq_notrace
msr cpsr_c, #SVC_MODE
.endm
#endif
.macro asm_trace_hardirqs_off, save=1
#if defined(CONFIG_TRACE_IRQFLAGS)
.if \save
stmdb sp!, {r0-r3, ip, lr}
.endif
bl trace_hardirqs_off
.if \save
ldmia sp!, {r0-r3, ip, lr}
.endif
#endif
.endm
.macro asm_trace_hardirqs_on, cond=al, save=1
#if defined(CONFIG_TRACE_IRQFLAGS)
/*
* actually the registers should be pushed and pop'd conditionally, but
* after bl the flags are certainly clobbered
*/
.if \save
stmdb sp!, {r0-r3, ip, lr}
.endif
bl\cond trace_hardirqs_on
.if \save
ldmia sp!, {r0-r3, ip, lr}
.endif
#endif
.endm
.macro disable_irq, save=1
disable_irq_notrace
asm_trace_hardirqs_off \save
.endm
.macro enable_irq
asm_trace_hardirqs_on
enable_irq_notrace
.endm
/*
* Save the current IRQ state and disable IRQs. Note that this macro
* assumes FIQs are enabled, and that the processor is in SVC mode.
*/
.macro save_and_disable_irqs, oldcpsr
#ifdef CONFIG_CPU_V7M
mrs \oldcpsr, primask
#else
mrs \oldcpsr, cpsr
#endif
disable_irq
.endm
.macro save_and_disable_irqs_notrace, oldcpsr
#ifdef CONFIG_CPU_V7M
mrs \oldcpsr, primask
#else
mrs \oldcpsr, cpsr
#endif
disable_irq_notrace
.endm
/*
* Restore interrupt state previously stored in a register. We don't
* guarantee that this will preserve the flags.
*/
.macro restore_irqs_notrace, oldcpsr
#ifdef CONFIG_CPU_V7M
msr primask, \oldcpsr
#else
msr cpsr_c, \oldcpsr
#endif
.endm
.macro restore_irqs, oldcpsr
tst \oldcpsr, #PSR_I_BIT
asm_trace_hardirqs_on cond=eq
restore_irqs_notrace \oldcpsr
.endm
/*
* Assembly version of "adr rd, BSYM(sym)". This should only be used to
* reference local symbols in the same assembly file which are to be
* resolved by the assembler. Other usage is undefined.
*/
.irp c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo
.macro badr\c, rd, sym
#ifdef CONFIG_THUMB2_KERNEL
adr\c \rd, \sym + 1
#else
adr\c \rd, \sym
#endif
.endm
.endr
/*
* Get current thread_info.
*/
.macro get_thread_info, rd
ARM( mov \rd, sp, lsr #THREAD_SIZE_ORDER + PAGE_SHIFT )
THUMB( mov \rd, sp )
THUMB( lsr \rd, \rd, #THREAD_SIZE_ORDER + PAGE_SHIFT )
mov \rd, \rd, lsl #THREAD_SIZE_ORDER + PAGE_SHIFT
.endm
/*
* Increment/decrement the preempt count.
*/
#ifdef CONFIG_PREEMPT_COUNT
.macro inc_preempt_count, ti, tmp
ldr \tmp, [\ti, #TI_PREEMPT] @ get preempt count
add \tmp, \tmp, #1 @ increment it
str \tmp, [\ti, #TI_PREEMPT]
.endm
.macro dec_preempt_count, ti, tmp
ldr \tmp, [\ti, #TI_PREEMPT] @ get preempt count
sub \tmp, \tmp, #1 @ decrement it
str \tmp, [\ti, #TI_PREEMPT]
.endm
.macro dec_preempt_count_ti, ti, tmp
get_thread_info \ti
dec_preempt_count \ti, \tmp
.endm
#else
.macro inc_preempt_count, ti, tmp
.endm
.macro dec_preempt_count, ti, tmp
.endm
.macro dec_preempt_count_ti, ti, tmp
.endm
#endif
#define USER(x...) \
9999: x; \
.pushsection __ex_table,"a"; \
.align 3; \
.long 9999b,9001f; \
.popsection
#ifdef CONFIG_SMP
#define ALT_SMP(instr...) \
9998: instr
/*
* Note: if you get assembler errors from ALT_UP() when building with
* CONFIG_THUMB2_KERNEL, you almost certainly need to use
* ALT_SMP( W(instr) ... )
*/
#define ALT_UP(instr...) \
.pushsection ".alt.smp.init", "a" ;\
.long 9998b ;\
9997: instr ;\
.if . - 9997b == 2 ;\
nop ;\
.endif ;\
.if . - 9997b != 4 ;\
.error "ALT_UP() content must assemble to exactly 4 bytes";\
.endif ;\
.popsection
#define ALT_UP_B(label) \
.equ up_b_offset, label - 9998b ;\
.pushsection ".alt.smp.init", "a" ;\
.long 9998b ;\
W(b) . + up_b_offset ;\
.popsection
#else
#define ALT_SMP(instr...)
#define ALT_UP(instr...) instr
#define ALT_UP_B(label) b label
#endif
/*
* Instruction barrier
*/
.macro instr_sync
#if __LINUX_ARM_ARCH__ >= 7
isb
#elif __LINUX_ARM_ARCH__ == 6
mcr p15, 0, r0, c7, c5, 4
#endif
.endm
/*
* SMP data memory barrier
*/
.macro smp_dmb mode
#ifdef CONFIG_SMP
#if __LINUX_ARM_ARCH__ >= 7
.ifeqs "\mode","arm"
ALT_SMP(dmb ish)
.else
ALT_SMP(W(dmb) ish)
.endif
#elif __LINUX_ARM_ARCH__ == 6
ALT_SMP(mcr p15, 0, r0, c7, c10, 5) @ dmb
#else
#error Incompatible SMP platform
#endif
.ifeqs "\mode","arm"
ALT_UP(nop)
.else
ALT_UP(W(nop))
.endif
#endif
.endm
#if defined(CONFIG_CPU_V7M)
/*
* setmode is used to assert to be in svc mode during boot. For v7-M
* this is done in __v7m_setup, so setmode can be empty here.
*/
.macro setmode, mode, reg
.endm
#elif defined(CONFIG_THUMB2_KERNEL)
.macro setmode, mode, reg
mov \reg, #\mode
msr cpsr_c, \reg
.endm
#else
.macro setmode, mode, reg
msr cpsr_c, #\mode
.endm
#endif
/*
* Helper macro to enter SVC mode cleanly and mask interrupts. reg is
* a scratch register for the macro to overwrite.
*
* This macro is intended for forcing the CPU into SVC mode at boot time.
* you cannot return to the original mode.
*/
.macro safe_svcmode_maskall reg:req
#if __LINUX_ARM_ARCH__ >= 6 && !defined(CONFIG_CPU_V7M)
mrs \reg , cpsr
eor \reg, \reg, #HYP_MODE
tst \reg, #MODE_MASK
bic \reg , \reg , #MODE_MASK
orr \reg , \reg , #PSR_I_BIT | PSR_F_BIT | SVC_MODE
THUMB( orr \reg , \reg , #PSR_T_BIT )
bne 1f
orr \reg, \reg, #PSR_A_BIT
badr lr, 2f
msr spsr_cxsf, \reg
__MSR_ELR_HYP(14)
__ERET
1: msr cpsr_c, \reg
2:
#else
/*
* workaround for possibly broken pre-v6 hardware
* (akita, Sharp Zaurus C-1000, PXA270-based)
*/
setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, \reg
#endif
.endm
/*
* STRT/LDRT access macros with ARM and Thumb-2 variants
*/
#ifdef CONFIG_THUMB2_KERNEL
.macro usraccoff, instr, reg, ptr, inc, off, cond, abort, t=TUSER()
9999:
.if \inc == 1
\instr\cond\()b\()\t\().w \reg, [\ptr, #\off]
.elseif \inc == 4
\instr\cond\()\t\().w \reg, [\ptr, #\off]
.else
.error "Unsupported inc macro argument"
.endif
.pushsection __ex_table,"a"
.align 3
.long 9999b, \abort
.popsection
.endm
.macro usracc, instr, reg, ptr, inc, cond, rept, abort
@ explicit IT instruction needed because of the label
@ introduced by the USER macro
.ifnc \cond,al
.if \rept == 1
itt \cond
.elseif \rept == 2
ittt \cond
.else
.error "Unsupported rept macro argument"
.endif
.endif
@ Slightly optimised to avoid incrementing the pointer twice
usraccoff \instr, \reg, \ptr, \inc, 0, \cond, \abort
.if \rept == 2
usraccoff \instr, \reg, \ptr, \inc, \inc, \cond, \abort
.endif
add\cond \ptr, #\rept * \inc
.endm
#else /* !CONFIG_THUMB2_KERNEL */
.macro usracc, instr, reg, ptr, inc, cond, rept, abort, t=TUSER()
.rept \rept
9999:
.if \inc == 1
\instr\cond\()b\()\t \reg, [\ptr], #\inc
.elseif \inc == 4
\instr\cond\()\t \reg, [\ptr], #\inc
.else
.error "Unsupported inc macro argument"
.endif
.pushsection __ex_table,"a"
.align 3
.long 9999b, \abort
.popsection
.endr
.endm
#endif /* CONFIG_THUMB2_KERNEL */
.macro strusr, reg, ptr, inc, cond=al, rept=1, abort=9001f
usracc str, \reg, \ptr, \inc, \cond, \rept, \abort
.endm
.macro ldrusr, reg, ptr, inc, cond=al, rept=1, abort=9001f
usracc ldr, \reg, \ptr, \inc, \cond, \rept, \abort
.endm
/* Utility macro for declaring string literals */
.macro string name:req, string
.type \name , #object
\name:
.asciz "\string"
.size \name , . - \name
.endm
.macro check_uaccess, addr:req, size:req, limit:req, tmp:req, bad:req
#ifndef CONFIG_CPU_USE_DOMAINS
adds \tmp, \addr, #\size - 1
sbcccs \tmp, \tmp, \limit
bcs \bad
#endif
.endm
.macro uaccess_disable, tmp, isb=1
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
/*
* Whenever we re-enter userspace, the domains should always be
* set appropriately.
*/
mov \tmp, #DACR_UACCESS_DISABLE
mcr p15, 0, \tmp, c3, c0, 0 @ Set domain register
.if \isb
instr_sync
.endif
#endif
.endm
.macro uaccess_enable, tmp, isb=1
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
/*
* Whenever we re-enter userspace, the domains should always be
* set appropriately.
*/
mov \tmp, #DACR_UACCESS_ENABLE
mcr p15, 0, \tmp, c3, c0, 0
.if \isb
instr_sync
.endif
#endif
.endm
.macro uaccess_save, tmp
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
mrc p15, 0, \tmp, c3, c0, 0
str \tmp, [sp, #SVC_DACR]
#endif
.endm
.macro uaccess_restore
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
ldr r0, [sp, #SVC_DACR]
mcr p15, 0, r0, c3, c0, 0
#endif
.endm
.irp c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo
.macro ret\c, reg
#if __LINUX_ARM_ARCH__ < 6
mov\c pc, \reg
#else
.ifeqs "\reg", "lr"
bx\c \reg
.else
mov\c pc, \reg
.endif
#endif
.endm
.endr
.macro ret.w, reg
ret \reg
#ifdef CONFIG_THUMB2_KERNEL
nop
#endif
.endm
.macro bug, msg, line
#ifdef CONFIG_THUMB2_KERNEL
1: .inst 0xde02
#else
1: .inst 0xe7f001f2
#endif
#ifdef CONFIG_DEBUG_BUGVERBOSE
.pushsection .rodata.str, "aMS", %progbits, 1
2: .asciz "\msg"
.popsection
.pushsection __bug_table, "aw"
.align 2
.word 1b, 2b
.hword \line
.popsection
#endif
.endm
#endif /* __ASM_ASSEMBLER_H__ */
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