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Commit 020f1053 authored by Jiaxun Yang's avatar Jiaxun Yang Committed by Greg Kroah-Hartman
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MIPS: mm: tlb-r4k: Uniquify TLB entries on init 



commit 35ad7e181541aa5757f9f316768d3e64403ec843 upstream.

Hardware or bootloader will initialize TLB entries to any value, which
may collide with kernel's UNIQUE_ENTRYHI value. On MIPS microAptiv/M5150
family of cores this will trigger machine check exception and cause boot
failure. On M5150 simulation this could happen 7 times out of 1000 boots.

Replace local_flush_tlb_all() with r4k_tlb_uniquify() which probes each
TLB ENTRIHI unique value for collisions before it's written, and in case
of collision try a different ASID.

Cc: stable@kernel.org
Signed-off-by: default avatarJiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: default avatarThomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1db292bc

arch/mips/mm/tlb-r4k.c

+55 −1
Original line number Diff line number Diff line
@@ -497,6 +497,60 @@ static int __init set_ntlb(char *str) 


__setup("ntlb=", set_ntlb);



/* Initialise all TLB entries with unique values */

static void r4k_tlb_uniquify(void)

{

	int entry = num_wired_entries();



	htw_stop();

	write_c0_entrylo0(0);

	write_c0_entrylo1(0);



	while (entry < current_cpu_data.tlbsize) {

		unsigned long asid_mask = cpu_asid_mask(&current_cpu_data);

		unsigned long asid = 0;

		int idx;



		/* Skip wired MMID to make ginvt_mmid work */

		if (cpu_has_mmid)

			asid = MMID_KERNEL_WIRED + 1;



		/* Check for match before using UNIQUE_ENTRYHI */

		do {

			if (cpu_has_mmid) {

				write_c0_memorymapid(asid);

				write_c0_entryhi(UNIQUE_ENTRYHI(entry));

			} else {

				write_c0_entryhi(UNIQUE_ENTRYHI(entry) | asid);

			}

			mtc0_tlbw_hazard();

			tlb_probe();

			tlb_probe_hazard();

			idx = read_c0_index();

			/* No match or match is on current entry */

			if (idx < 0 || idx == entry)

				break;

			/*

			 * If we hit a match, we need to try again with

			 * a different ASID.

			 */

			asid++;

		} while (asid < asid_mask);



		if (idx >= 0 && idx != entry)

			panic("Unable to uniquify TLB entry %d", idx);



		write_c0_index(entry);

		mtc0_tlbw_hazard();

		tlb_write_indexed();

		entry++;

	}



	tlbw_use_hazard();

	htw_start();

	flush_micro_tlb();

}



/*

 * Configure TLB (for init or after a CPU has been powered off).

 */
@@ -536,7 +590,7 @@ static void r4k_tlb_configure(void) 
	temp_tlb_entry = current_cpu_data.tlbsize - 1;



	/* From this point on the ARC firmware is dead.	 */

	local_flush_tlb_all();

	r4k_tlb_uniquify();



	/* Did I tell you that ARC SUCKS?  */

}