From 1543e317f1da31b75942316931e8f491a8920811 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Thu, 04 Jan 2024 10:08:02 +0000
Subject: [PATCH] disable FB

---
 kernel/arch/mips/mm/fault.c |   49 +++++++++++++++++++++++--------------------------
 1 files changed, 23 insertions(+), 26 deletions(-)

diff --git a/kernel/arch/mips/mm/fault.c b/kernel/arch/mips/mm/fault.c
index 73d8a0f..7c871b1 100644
--- a/kernel/arch/mips/mm/fault.c
+++ b/kernel/arch/mips/mm/fault.c
@@ -44,7 +44,7 @@
 	const int field = sizeof(unsigned long) * 2;
 	int si_code;
 	vm_fault_t fault;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+	unsigned int flags = FAULT_FLAG_DEFAULT;
 
 	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
 
@@ -96,8 +96,10 @@
 
 	if (user_mode(regs))
 		flags |= FAULT_FLAG_USER;
+
+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 retry:
-	down_read(&mm->mmap_sem);
+	mmap_read_lock(mm);
 	vma = find_vma(mm, address);
 	if (!vma)
 		goto bad_area;
@@ -142,7 +144,7 @@
 				goto bad_area;
 			}
 		} else {
-			if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
+			if (unlikely(!vma_is_accessible(vma)))
 				goto bad_area;
 		}
 	}
@@ -152,12 +154,11 @@
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags, regs);
 
-	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+	if (fault_signal_pending(fault, regs))
 		return;
 
-	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
@@ -168,21 +169,11 @@
 		BUG();
 	}
 	if (flags & FAULT_FLAG_ALLOW_RETRY) {
-		if (fault & VM_FAULT_MAJOR) {
-			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
-						  regs, address);
-			tsk->maj_flt++;
-		} else {
-			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
-						  regs, address);
-			tsk->min_flt++;
-		}
 		if (fault & VM_FAULT_RETRY) {
-			flags &= ~FAULT_FLAG_ALLOW_RETRY;
 			flags |= FAULT_FLAG_TRIED;
 
 			/*
-			 * No need to up_read(&mm->mmap_sem) as we would
+			 * No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */
@@ -191,7 +182,7 @@
 		}
 	}
 
-	up_read(&mm->mmap_sem);
+	mmap_read_unlock(mm);
 	return;
 
 /*
@@ -199,7 +190,7 @@
  * Fix it, but check if it's kernel or user first..
  */
 bad_area:
-	up_read(&mm->mmap_sem);
+	mmap_read_unlock(mm);
 
 bad_area_nosemaphore:
 	/* User mode accesses just cause a SIGSEGV */
@@ -223,7 +214,7 @@
 			pr_cont("\n");
 		}
 		current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
-		force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);
+		force_sig_fault(SIGSEGV, si_code, (void __user *)address);
 		return;
 	}
 
@@ -251,14 +242,14 @@
 	 * We ran out of memory, call the OOM killer, and return the userspace
 	 * (which will retry the fault, or kill us if we got oom-killed).
 	 */
-	up_read(&mm->mmap_sem);
+	mmap_read_unlock(mm);
 	if (!user_mode(regs))
 		goto no_context;
 	pagefault_out_of_memory();
 	return;
 
 do_sigbus:
-	up_read(&mm->mmap_sem);
+	mmap_read_unlock(mm);
 
 	/* Kernel mode? Handle exceptions or die */
 	if (!user_mode(regs))
@@ -279,7 +270,7 @@
 #endif
 	current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
 	tsk->thread.cp0_badvaddr = address;
-	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk);
+	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
 
 	return;
 #ifndef CONFIG_64BIT
@@ -292,8 +283,9 @@
 		 * Do _not_ use "tsk" here. We might be inside
 		 * an interrupt in the middle of a task switch..
 		 */
-		int offset = __pgd_offset(address);
+		int offset = pgd_index(address);
 		pgd_t *pgd, *pgd_k;
+		p4d_t *p4d, *p4d_k;
 		pud_t *pud, *pud_k;
 		pmd_t *pmd, *pmd_k;
 		pte_t *pte_k;
@@ -305,8 +297,13 @@
 			goto no_context;
 		set_pgd(pgd, *pgd_k);
 
-		pud = pud_offset(pgd, address);
-		pud_k = pud_offset(pgd_k, address);
+		p4d = p4d_offset(pgd, address);
+		p4d_k = p4d_offset(pgd_k, address);
+		if (!p4d_present(*p4d_k))
+			goto no_context;
+
+		pud = pud_offset(p4d, address);
+		pud_k = pud_offset(p4d_k, address);
 		if (!pud_present(*pud_k))
 			goto no_context;
 

--
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