Commit 12e7804c authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARC: mm: remove tlb paranoid code 



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

Signed-off-by: default avatarVineet Gupta <vgupta@kernel.org>
parent 6128df5b

arch/arc/Kconfig

+0 −3
Original line number Diff line number Diff line
@@ -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

	  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

	bool "Paranoid checks in Static Keys (jump labels) code"

	depends on JUMP_LABEL

arch/arc/include/asm/mmu.h

+0 −6
Original line number Diff line number Diff line
@@ -64,12 +64,6 @@ typedef struct { 
	unsigned long asid[NR_CPUS];	/* 8 bit MMU PID + Generation cycle */

} 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);

extern char *arc_mmu_mumbojumbo(int cpu_id, char *buf, int len);

void read_decode_mmu_bcr(void);

arch/arc/mm/tlb.c

+0 −40
Original line number Diff line number Diff line
@@ -400,7 +400,6 @@ void create_tlb(struct vm_area_struct *vma, unsigned long vaddr, pte_t *ptep) 
	 *

	 * Removing the assumption involves

	 * -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

	 *  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);



	tlb_paranoid_check(asid_mm(vma->vm_mm, smp_processor_id()), vaddr);



	vaddr &= PAGE_MASK;



	/* update this PTE credentials */
@@ -818,40 +815,3 @@ void do_tlb_overlap_fault(unsigned long cause, unsigned long address, 


	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

arch/arc/mm/tlbex.S

+0 −50
Original line number Diff line number Diff line
@@ -93,11 +93,6 @@ ex_saved_reg1: 
	st_s  r1, [r0, 4]

	st_s  r2, [r0, 8]

	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



.macro TLBMISS_RESTORE_REGS
@@ -146,51 +141,6 @@ ex_saved_reg1: 


#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

;============================================================================