6.12-stable review patch. If anyone has any objections, please let me know.

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From: Maciej W. Rozycki macro@orcam.me.uk

commit 9f048fa487409e364cf866c957cf0b0d782ca5a3 upstream.

Depending on the particular CPU implementation a TLB shutdown may occur if multiple matching entries are detected upon the execution of a TLBP or the TLBWI/TLBWR instructions. Given that we don't know what entries we have been handed we need to be very careful with the initial TLB setup and avoid all these instructions.

Therefore read all the TLB entries one by one with the TLBR instruction, bypassing the content addressing logic, and truncate any large pages in place so as to avoid a case in the second step where an incoming entry for a large page at a lower address overlaps with a replacement entry chosen at another index. Then preinitialize the TLB using addresses outside our usual unique range and avoiding clashes with any entries received, before making the usual call to local_flush_tlb_all().

This fixes (at least) R4x00 cores if TLBP hits multiple matching TLB entries (SGI IP22 PROM for examples sets up all TLBs to the same virtual address).

Signed-off-by: Maciej W. Rozycki macro@orcam.me.uk Fixes: 35ad7e181541 ("MIPS: mm: tlb-r4k: Uniquify TLB entries on init") Cc: stable@vger.kernel.org Reviewed-by: Jiaxun Yang jiaxun.yang@flygoat.com Tested-by: Jiaxun Yang jiaxun.yang@flygoat.com # Boston I6400, M5150 sim Signed-off-by: Thomas Bogendoerfer tsbogend@alpha.franken.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/mips/mm/tlb-r4k.c | 102 ++++++++++++++++++++++++++++++------------------- 1 file changed, 64 insertions(+), 38 deletions(-)

--- a/arch/mips/mm/tlb-r4k.c +++ b/arch/mips/mm/tlb-r4k.c @@ -15,6 +15,7 @@ #include <linux/mm.h> #include <linux/hugetlb.h> #include <linux/export.h> +#include <linux/sort.h>

#include <asm/cpu.h> #include <asm/cpu-type.h> @@ -508,55 +509,79 @@ static int __init set_ntlb(char *str)

__setup("ntlb=", set_ntlb);

-/* Initialise all TLB entries with unique values */ + +/* Comparison function for EntryHi VPN fields. */ +static int r4k_vpn_cmp(const void *a, const void *b) +{ + long v = *(unsigned long *)a - *(unsigned long *)b; + int s = sizeof(long) > sizeof(int) ? sizeof(long) * 8 - 1: 0; + return s ? (v != 0) | v >> s : v; +} + +/* + * Initialise all TLB entries with unique values that do not clash with + * what we have been handed over and what we'll be using ourselves. + */ static void r4k_tlb_uniquify(void) { - int entry = num_wired_entries(); + unsigned long tlb_vpns[1 << MIPS_CONF1_TLBS_SIZE]; + int tlbsize = current_cpu_data.tlbsize; + int start = num_wired_entries(); + unsigned long vpn_mask; + int cnt, ent, idx, i; + + vpn_mask = GENMASK(cpu_vmbits - 1, 13); + vpn_mask |= IS_ENABLED(CONFIG_64BIT) ? 3ULL << 62 : 1 << 31;

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; + for (i = start, cnt = 0; i < tlbsize; i++, cnt++) { + unsigned long vpn;

- /* Skip wired MMID to make ginvt_mmid work */ - if (cpu_has_mmid) - asid = MMID_KERNEL_WIRED + 1; + write_c0_index(i); + mtc0_tlbr_hazard(); + tlb_read(); + tlb_read_hazard(); + vpn = read_c0_entryhi(); + vpn &= vpn_mask & PAGE_MASK; + tlb_vpns[cnt] = vpn;

- /* 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); + /* Prevent any large pages from overlapping regular ones. */ + write_c0_pagemask(read_c0_pagemask() & PM_DEFAULT_MASK); mtc0_tlbw_hazard(); tlb_write_indexed(); - entry++; + tlbw_use_hazard(); }

+ sort(tlb_vpns, cnt, sizeof(tlb_vpns[0]), r4k_vpn_cmp, NULL); + + write_c0_pagemask(PM_DEFAULT_MASK); + write_c0_entrylo0(0); + write_c0_entrylo1(0); + + idx = 0; + ent = tlbsize; + for (i = start; i < tlbsize; i++) + while (1) { + unsigned long entryhi, vpn; + + entryhi = UNIQUE_ENTRYHI(ent); + vpn = entryhi & vpn_mask & PAGE_MASK; + + if (idx >= cnt || vpn < tlb_vpns[idx]) { + write_c0_entryhi(entryhi); + write_c0_index(i); + mtc0_tlbw_hazard(); + tlb_write_indexed(); + ent++; + break; + } else if (vpn == tlb_vpns[idx]) { + ent++; + } else { + idx++; + } + } + tlbw_use_hazard(); htw_start(); flush_micro_tlb(); @@ -602,6 +627,7 @@ static void r4k_tlb_configure(void)

/* From this point on the ARC firmware is dead. */ r4k_tlb_uniquify(); + local_flush_tlb_all();

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