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Revert "ARM: 6943/1: mm: use TTBR1 instead of reserved context ID"

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This reverts commit 52af9c6cd8.

Will Deacon reports that:

 In 52af9c6c ("ARM: 6943/1: mm: use TTBR1 instead of reserved context ID")
 I updated the ASID rollover code to use only the kernel page tables
 whilst updating the ASID.

 Unfortunately, the code to restore the user page tables was part of a
 later patch which isn't yet in mainline, so this leaves the code
 quite broken.

We're also in the process of eliminating __ARCH_WANT_INTERRUPTS_ON_CTXSW
from ARM, so lets revert these until we can properly sort out what we're
doing with the ARM context switching.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2011-06-09 10:10:27 +01:00
parent 17ee083b78
commit 07989b7ad6
2 changed files with 11 additions and 10 deletions
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11
arch/arm/mm/context.c
View File

@ -24,7 +24,9 @@ DEFINE_PER_CPU(struct mm_struct *, current_mm);
/*
* We fork()ed a process, and we need a new context for the child
* to run in.
* to run in. We reserve version 0 for initial tasks so we will
* always allocate an ASID. The ASID 0 is reserved for the TTBR
* register changing sequence.
*/
void __init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
@ -34,11 +36,8 @@ void __init_new_context(struct task_struct *tsk, struct mm_struct *mm)
static void flush_context(void)
{
u32 ttb;
/* Copy TTBR1 into TTBR0 */
asm volatile("mrc p15, 0, %0, c2, c0, 1\n"
"mcr p15, 0, %0, c2, c0, 0"
: "=r" (ttb));
/* set the reserved ASID before flushing the TLB */
asm("mcr p15, 0, %0, c13, c0, 1\n" : : "r" (0));
isb();
local_flush_tlb_all();
if (icache_is_vivt_asid_tagged()) {

10
arch/arm/mm/proc-v7.S
View File

@ -108,16 +108,18 @@ ENTRY(cpu_v7_switch_mm)
#ifdef CONFIG_ARM_ERRATA_430973
mcr p15, 0, r2, c7, c5, 6 @ flush BTAC/BTB
#endif
mrc p15, 0, r2, c2, c0, 1 @ load TTB 1
mcr p15, 0, r2, c2, c0, 0 @ into TTB 0
#ifdef CONFIG_ARM_ERRATA_754322
dsb
#endif
mcr p15, 0, r2, c13, c0, 1 @ set reserved context ID
isb
1: mcr p15, 0, r0, c2, c0, 0 @ set TTB 0
isb
#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)