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ARC: mm: remove tlb paranoid code

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This was used back in arc700 days when ASID allocator was fragile.
Not needed in last 5 years

Signed-off-by: Vineet Gupta <vgupta@kernel.org>
This commit is contained in:
Vineet Gupta 2019-09-09 16:59:59 -07:00
parent 6128df5be4
commit 12e7804c26
4 changed files with 0 additions and 99 deletions
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3
arch/arc/Kconfig
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@ -537,9 +537,6 @@ config ARC_DW2_UNWIND
If you don't debug the kernel, you can say N, but we may not be able If you don't debug the kernel, you can say N, but we may not be able
to solve problems without frame unwind information to solve problems without frame unwind information
config ARC_DBG_TLB_PARANOIA
bool "Paranoia Checks in Low Level TLB Handlers"
config ARC_DBG_JUMP_LABEL config ARC_DBG_JUMP_LABEL
bool "Paranoid checks in Static Keys (jump labels) code" bool "Paranoid checks in Static Keys (jump labels) code"
depends on JUMP_LABEL depends on JUMP_LABEL

6
arch/arc/include/asm/mmu.h
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@ -64,12 +64,6 @@ typedef struct {
unsigned long asid[NR_CPUS]; /* 8 bit MMU PID + Generation cycle */ unsigned long asid[NR_CPUS]; /* 8 bit MMU PID + Generation cycle */
} mm_context_t; } mm_context_t;
#ifdef CONFIG_ARC_DBG_TLB_PARANOIA
void tlb_paranoid_check(unsigned int mm_asid, unsigned long address);
#else
#define tlb_paranoid_check(a, b)
#endif
void arc_mmu_init(void); void arc_mmu_init(void);
extern char *arc_mmu_mumbojumbo(int cpu_id, char *buf, int len); extern char *arc_mmu_mumbojumbo(int cpu_id, char *buf, int len);
void read_decode_mmu_bcr(void); void read_decode_mmu_bcr(void);

40
arch/arc/mm/tlb.c
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@ -400,7 +400,6 @@ void create_tlb(struct vm_area_struct *vma, unsigned long vaddr, pte_t *ptep)
* *
* Removing the assumption involves * Removing the assumption involves
* -Using vma->mm->context{ASID,SASID}, as opposed to MMU reg. * -Using vma->mm->context{ASID,SASID}, as opposed to MMU reg.
* -Fix the TLB paranoid debug code to not trigger false negatives.
* -More importantly it makes this handler inconsistent with fast-path * -More importantly it makes this handler inconsistent with fast-path
* TLB Refill handler which always deals with "current" * TLB Refill handler which always deals with "current"
* *
@ -423,8 +422,6 @@ void create_tlb(struct vm_area_struct *vma, unsigned long vaddr, pte_t *ptep)
local_irq_save(flags); local_irq_save(flags);
tlb_paranoid_check(asid_mm(vma->vm_mm, smp_processor_id()), vaddr);
vaddr &= PAGE_MASK; vaddr &= PAGE_MASK;
/* update this PTE credentials */ /* update this PTE credentials */
@ -818,40 +815,3 @@ void do_tlb_overlap_fault(unsigned long cause, unsigned long address,
local_irq_restore(flags); local_irq_restore(flags);
} }
/***********************************************************************
* Diagnostic Routines
* -Called from Low Level TLB Handlers if things don;t look good
**********************************************************************/
#ifdef CONFIG_ARC_DBG_TLB_PARANOIA
/*
* Low Level ASM TLB handler calls this if it finds that HW and SW ASIDS
* don't match
*/
void print_asid_mismatch(int mm_asid, int mmu_asid, int is_fast_path)
{
pr_emerg("ASID Mismatch in %s Path Handler: sw-pid=0x%x hw-pid=0x%x\n",
is_fast_path ? "Fast" : "Slow", mm_asid, mmu_asid);
__asm__ __volatile__("flag 1");
}
void tlb_paranoid_check(unsigned int mm_asid, unsigned long addr)
{
unsigned int mmu_asid;
mmu_asid = read_aux_reg(ARC_REG_PID) & 0xff;
/*
* At the time of a TLB miss/installation
* - HW version needs to match SW version
* - SW needs to have a valid ASID
*/
if (addr < 0x70000000 &&
((mm_asid == MM_CTXT_NO_ASID) ||
(mmu_asid != (mm_asid & MM_CTXT_ASID_MASK))))
print_asid_mismatch(mm_asid, mmu_asid, 0);
}
#endif

50
arch/arc/mm/tlbex.S
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@ -93,11 +93,6 @@ ex_saved_reg1:
st_s r1, [r0, 4] st_s r1, [r0, 4]
st_s r2, [r0, 8] st_s r2, [r0, 8]
st_s r3, [r0, 12] st_s r3, [r0, 12]
; VERIFY if the ASID in MMU-PID Reg is same as
; one in Linux data structures
tlb_paranoid_check_asm
.endm .endm
.macro TLBMISS_RESTORE_REGS .macro TLBMISS_RESTORE_REGS
@ -146,51 +141,6 @@ ex_saved_reg1:
#endif #endif
;============================================================================
; Troubleshooting Stuff
;============================================================================
; Linux keeps ASID (Address Space ID) in task->active_mm->context.asid
; When Creating TLB Entries, instead of doing 3 dependent loads from memory,
; we use the MMU PID Reg to get current ASID.
; In bizzare scenrios SW and HW ASID can get out-of-sync which is trouble.
; So we try to detect this in TLB Mis shandler
.macro tlb_paranoid_check_asm
#ifdef CONFIG_ARC_DBG_TLB_PARANOIA
GET_CURR_TASK_ON_CPU r3
ld r0, [r3, TASK_ACT_MM]
ld r0, [r0, MM_CTXT+MM_CTXT_ASID]
breq r0, 0, 55f ; Error if no ASID allocated
lr r1, [ARC_REG_PID]
and r1, r1, 0xFF
and r2, r0, 0xFF ; MMU PID bits only for comparison
breq r1, r2, 5f
55:
; Error if H/w and S/w ASID don't match, but NOT if in kernel mode
lr r2, [erstatus]
bbit0 r2, STATUS_U_BIT, 5f
; We sure are in troubled waters, Flag the error, but to do so
; need to switch to kernel mode stack to call error routine
GET_TSK_STACK_BASE r3, sp
; Call printk to shoutout aloud
mov r2, 1
j print_asid_mismatch
5: ; ASIDs match so proceed normally
nop
#endif
.endm
;============================================================================ ;============================================================================
;TLB Miss handling Code ;TLB Miss handling Code
;============================================================================ ;============================================================================