From 07989b7ad63af424886ff922fd3bcca9e00ffa78 Mon Sep 17 00:00:00 2001 From: Russell King Date: Thu, 9 Jun 2011 10:10:27 +0100 Subject: Revert "ARM: 6943/1: mm: use TTBR1 instead of reserved context ID" This reverts commit 52af9c6cd863fe37d1103035ec7ee22ac1296458. 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 --- arch/arm/mm/context.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'arch/arm/mm/context.c') diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c index 8bfae964b133..b6c776ae4039 100644 --- a/arch/arm/mm/context.c +++ b/arch/arm/mm/context.c @@ -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()) { -- cgit v1.2.3 From a0a54d37b4b1d1f55d1e81e8ffc223bb85472fa3 Mon Sep 17 00:00:00 2001 From: Russell King Date: Thu, 9 Jun 2011 10:12:41 +0100 Subject: Revert "ARM: 6944/1: mm: allow ASID 0 to be allocated to tasks" This reverts commit 45b95235b0ac86cef2ad4480b0618b8778847479. 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 context switching. Signed-off-by: Russell King --- arch/arm/mm/context.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/arm/mm/context.c') diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c index b6c776ae4039..b0ee9ba3cfab 100644 --- a/arch/arm/mm/context.c +++ b/arch/arm/mm/context.c @@ -93,7 +93,7 @@ static void reset_context(void *info) return; smp_rmb(); - asid = cpu_last_asid + cpu; + asid = cpu_last_asid + cpu + 1; flush_context(); set_mm_context(mm, asid); @@ -143,13 +143,13 @@ void __new_context(struct mm_struct *mm) * to start a new version and flush the TLB. */ if (unlikely((asid & ~ASID_MASK) == 0)) { - asid = cpu_last_asid + smp_processor_id(); + asid = cpu_last_asid + smp_processor_id() + 1; flush_context(); #ifdef CONFIG_SMP smp_wmb(); smp_call_function(reset_context, NULL, 1); #endif - cpu_last_asid += NR_CPUS - 1; + cpu_last_asid += NR_CPUS; } set_mm_context(mm, asid); -- cgit v1.2.3