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linux-next/arch/arm/mm/proc-v7-2level.S
Will Deacon b6ccb9803e ARM: 7954/1: mm: remove remaining domain support from ARMv6 
CPU_32v6 currently selects CPU_USE_DOMAINS if CPU_V6 and MMU. This is
because ARM 1136 r0pX CPUs lack the v6k extensions, and therefore do
not have hardware thread registers. The lack of these registers requires
the kernel to update the vectors page at each context switch in order to
write a new TLS pointer. This write must be done via the userspace
mapping, since aliasing caches can lead to expensive flushing when using
kmap. Finally, this requires the vectors page to be mapped r/w for
kernel and r/o for user, which has implications for things like put_user
which must trigger CoW appropriately when targetting user pages.

The upshot of all this is that a v6/v7 kernel makes use of domains to
segregate kernel and user memory accesses. This has the nasty
side-effect of making device mappings executable, which has been
observed to cause subtle bugs on recent cores (e.g. Cortex-A15
performing a speculative instruction fetch from the GIC and acking an
interrupt in the process).

This patch solves this problem by removing the remaining domain support
from ARMv6. A new memory type is added specifically for the vectors page
which allows that page (and only that page) to be mapped as user r/o,
kernel r/w. All other user r/o pages are mapped also as kernel r/o.
Patch co-developed with Russell King.

Cc: <stable@vger.kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-02-10 11:48:13 +00:00

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4.3 KiB
ArmAsm
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/*
* arch/arm/mm/proc-v7-2level.S
*
* Copyright (C) 2001 Deep Blue Solutions Ltd.
*
* 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.
*/
#define TTB_S (1 << 1)
#define TTB_RGN_NC (0 << 3)
#define TTB_RGN_OC_WBWA (1 << 3)
#define TTB_RGN_OC_WT (2 << 3)
#define TTB_RGN_OC_WB (3 << 3)
#define TTB_NOS (1 << 5)
#define TTB_IRGN_NC ((0 << 0) | (0 << 6))
#define TTB_IRGN_WBWA ((0 << 0) | (1 << 6))
#define TTB_IRGN_WT ((1 << 0) | (0 << 6))
#define TTB_IRGN_WB ((1 << 0) | (1 << 6))
/* PTWs cacheable, inner WB not shareable, outer WB not shareable */
#define TTB_FLAGS_UP TTB_IRGN_WB|TTB_RGN_OC_WB
#define PMD_FLAGS_UP PMD_SECT_WB
/* PTWs cacheable, inner WBWA shareable, outer WBWA not shareable */
#define TTB_FLAGS_SMP TTB_IRGN_WBWA|TTB_S|TTB_NOS|TTB_RGN_OC_WBWA
#define PMD_FLAGS_SMP PMD_SECT_WBWA|PMD_SECT_S
/*
* cpu_v7_switch_mm(pgd_phys, tsk)
*
* Set the translation table base pointer to be pgd_phys
*
* - pgd_phys - physical address of new TTB
*
* It is assumed that:
* - we are not using split page tables
*/
ENTRY(cpu_v7_switch_mm)
#ifdef CONFIG_MMU
mov r2, #0
mmid r1, r1 @ get mm->context.id
ALT_SMP(orr r0, r0, #TTB_FLAGS_SMP)
ALT_UP(orr r0, r0, #TTB_FLAGS_UP)
#ifdef CONFIG_ARM_ERRATA_430973
mcr p15, 0, r2, c7, c5, 6 @ flush BTAC/BTB
#endif
#ifdef CONFIG_PID_IN_CONTEXTIDR
mrc p15, 0, r2, c13, c0, 1 @ read current context ID
lsr r2, r2, #8 @ extract the PID
bfi r1, r2, #8, #24 @ insert into new context ID
#endif
#ifdef CONFIG_ARM_ERRATA_754322
dsb
#endif
mcr p15, 0, r1, c13, c0, 1 @ set context ID
isb
mcr p15, 0, r0, c2, c0, 0 @ set TTB 0
isb
#endif
mov pc, lr
ENDPROC(cpu_v7_switch_mm)
/*
* cpu_v7_set_pte_ext(ptep, pte)
*
* Set a level 2 translation table entry.
*
* - ptep - pointer to level 2 translation table entry
* (hardware version is stored at +2048 bytes)
* - pte - PTE value to store
* - ext - value for extended PTE bits
*/
ENTRY(cpu_v7_set_pte_ext)
#ifdef CONFIG_MMU
str r1, [r0] @ linux version
bic r3, r1, #0x000003f0
bic r3, r3, #PTE_TYPE_MASK
orr r3, r3, r2
orr r3, r3, #PTE_EXT_AP0 | 2
tst r1, #1 << 4
orrne r3, r3, #PTE_EXT_TEX(1)
eor r1, r1, #L_PTE_DIRTY
tst r1, #L_PTE_RDONLY | L_PTE_DIRTY
orrne r3, r3, #PTE_EXT_APX
tst r1, #L_PTE_USER
orrne r3, r3, #PTE_EXT_AP1
tst r1, #L_PTE_XN
orrne r3, r3, #PTE_EXT_XN
tst r1, #L_PTE_YOUNG
tstne r1, #L_PTE_VALID
eorne r1, r1, #L_PTE_NONE
tstne r1, #L_PTE_NONE
moveq r3, #0
ARM( str r3, [r0, #2048]! )
THUMB( add r0, r0, #2048 )
THUMB( str r3, [r0] )
ALT_SMP(W(nop))
ALT_UP (mcr p15, 0, r0, c7, c10, 1) @ flush_pte
#endif
mov pc, lr
ENDPROC(cpu_v7_set_pte_ext)
/*
* Memory region attributes with SCTLR.TRE=1
*
* n = TEX[0],C,B
* TR = PRRR[2n+1:2n] - memory type
* IR = NMRR[2n+1:2n] - inner cacheable property
* OR = NMRR[2n+17:2n+16] - outer cacheable property
*
* n TR IR OR
* UNCACHED 000 00
* BUFFERABLE 001 10 00 00
* WRITETHROUGH 010 10 10 10
* WRITEBACK 011 10 11 11
* reserved 110
* WRITEALLOC 111 10 01 01
* DEV_SHARED 100 01
* DEV_NONSHARED 100 01
* DEV_WC 001 10
* DEV_CACHED 011 10
*
* Other attributes:
*
* DS0 = PRRR[16] = 0 - device shareable property
* DS1 = PRRR[17] = 1 - device shareable property
* NS0 = PRRR[18] = 0 - normal shareable property
* NS1 = PRRR[19] = 1 - normal shareable property
* NOS = PRRR[24+n] = 1 - not outer shareable
*/
.equ PRRR, 0xff0a81a8
.equ NMRR, 0x40e040e0
/*
* Macro for setting up the TTBRx and TTBCR registers.
* - \ttb0 and \ttb1 updated with the corresponding flags.
*/
.macro v7_ttb_setup, zero, ttbr0, ttbr1, tmp
mcr p15, 0, \zero, c2, c0, 2 @ TTB control register
ALT_SMP(orr \ttbr0, \ttbr0, #TTB_FLAGS_SMP)
ALT_UP(orr \ttbr0, \ttbr0, #TTB_FLAGS_UP)
ALT_SMP(orr \ttbr1, \ttbr1, #TTB_FLAGS_SMP)
ALT_UP(orr \ttbr1, \ttbr1, #TTB_FLAGS_UP)
mcr p15, 0, \ttbr1, c2, c0, 1 @ load TTB1
.endm
/* AT
* TFR EV X F I D LR S
* .EEE ..EE PUI. .T.T 4RVI ZWRS BLDP WCAM
* rxxx rrxx xxx0 0101 xxxx xxxx x111 xxxx < forced
* 01 0 110 0011 1100 .111 1101 < we want
*/
.align 2
.type v7_crval, #object
v7_crval:
crval clear=0x2120c302, mmuset=0x10c03c7d, ucset=0x00c01c7c
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