6.15-stable review patch. If anyone has any objections, please let me know.
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From: Jiaxun Yang jiaxun.yang@flygoat.com
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: Jiaxun Yang jiaxun.yang@flygoat.com Signed-off-by: Thomas Bogendoerfer tsbogend@alpha.franken.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/mips/mm/tlb-r4k.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 55 insertions(+), 1 deletion(-)
--- a/arch/mips/mm/tlb-r4k.c +++ b/arch/mips/mm/tlb-r4k.c @@ -508,6 +508,60 @@ 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(¤t_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). */ @@ -547,7 +601,7 @@ 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? */ }