kernel: Fix boot of realtek rtl838x

Revert two patches from upstream Linux:
135178e90a
63a93d1cd6

This fixes a boot hang on realtek rtl838x switches.
This is the last printed message:
Inode-cache hash table entries: 8192 (order: 3, 32768 bytes, linear)

Thread on mips mailing list:
https://lore.kernel.org/linux-mips/b35fe4b3-8f42-49f4-a6bf-9f0e56d4050c@hauke-m.de/T/#u

Link: https://github.com/openwrt/openwrt/pull/21166
Signed-off-by: John Audia <therealgraysky@proton.me>
Link: https://github.com/openwrt/openwrt/pull/21126
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
This commit is contained in:
Hauke Mehrtens
2025-12-15 02:02:35 +01:00
parent 97e9d7038e
commit 0bfc66e7b5
2 changed files with 206 additions and 0 deletions

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@@ -0,0 +1,60 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Hauke Mehrtens <hauke@hauke-m.de>
Date: Mon, 15 Dec 2025 01:45:07 +0100
Subject: Revert "MIPS: mm: kmalloc tlb_vpn array to avoid stack overflow"
This reverts commit 63a93d1cd6077d79735f804f5a4957bfb240280c.
---
arch/mips/mm/tlb-r4k.c | 18 ++----------------
1 file changed, 2 insertions(+), 16 deletions(-)
--- a/arch/mips/mm/tlb-r4k.c
+++ b/arch/mips/mm/tlb-r4k.c
@@ -12,7 +12,6 @@
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/smp.h>
-#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/export.h>
@@ -523,26 +522,17 @@ static int r4k_vpn_cmp(const void *a, co
* 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 __ref r4k_tlb_uniquify(void)
+static void r4k_tlb_uniquify(void)
{
+ unsigned long tlb_vpns[1 << MIPS_CONF1_TLBS_SIZE];
int tlbsize = current_cpu_data.tlbsize;
- bool use_slab = slab_is_available();
int start = num_wired_entries();
- phys_addr_t tlb_vpn_size;
- unsigned long *tlb_vpns;
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;
- tlb_vpn_size = tlbsize * sizeof(*tlb_vpns);
- tlb_vpns = (use_slab ?
- kmalloc(tlb_vpn_size, GFP_KERNEL) :
- memblock_alloc_raw(tlb_vpn_size, sizeof(*tlb_vpns)));
- if (WARN_ON(!tlb_vpns))
- return; /* Pray local_flush_tlb_all() is good enough. */
-
htw_stop();
for (i = start, cnt = 0; i < tlbsize; i++, cnt++) {
@@ -595,10 +585,6 @@ static void __ref r4k_tlb_uniquify(void)
tlbw_use_hazard();
htw_start();
flush_micro_tlb();
- if (use_slab)
- kfree(tlb_vpns);
- else
- memblock_free(tlb_vpns, tlb_vpn_size);
}
/*

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@@ -0,0 +1,146 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Hauke Mehrtens <hauke@hauke-m.de>
Date: Mon, 15 Dec 2025 01:45:20 +0100
Subject: Revert "MIPS: mm: Prevent a TLB shutdown on initial uniquification"
This reverts commit 135178e90aa43ad949534e1d6e376c4034942caa.
---
arch/mips/mm/tlb-r4k.c | 100 +++++++++++++++--------------------------
1 file changed, 37 insertions(+), 63 deletions(-)
--- a/arch/mips/mm/tlb-r4k.c
+++ b/arch/mips/mm/tlb-r4k.c
@@ -15,7 +15,6 @@
#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>
@@ -509,79 +508,55 @@ static int __init set_ntlb(char *str)
__setup("ntlb=", set_ntlb);
-
-/* 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.
- */
+/* Initialise all TLB entries with unique values */
static void r4k_tlb_uniquify(void)
{
- 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;
+ int entry = num_wired_entries();
htw_stop();
+ write_c0_entrylo0(0);
+ write_c0_entrylo1(0);
- for (i = start, cnt = 0; i < tlbsize; i++, cnt++) {
- unsigned long vpn;
+ while (entry < current_cpu_data.tlbsize) {
+ unsigned long asid_mask = cpu_asid_mask(&current_cpu_data);
+ unsigned long asid = 0;
+ int idx;
- 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;
+ /* Skip wired MMID to make ginvt_mmid work */
+ if (cpu_has_mmid)
+ asid = MMID_KERNEL_WIRED + 1;
- /* Prevent any large pages from overlapping regular ones. */
- write_c0_pagemask(read_c0_pagemask() & PM_DEFAULT_MASK);
+ /* 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();
- tlbw_use_hazard();
+ entry++;
}
- 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();
@@ -627,7 +602,6 @@ 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? */
}