From 5e1f225fc0d4793e1fdc85660b1fdf69095c38f3 Mon Sep 17 00:00:00 2001
From: Ralf Baechle <ralf@linux-mips.org>
Date: Wed, 23 May 2001 12:52:58 +0000
Subject: Fix vmalloc for mips64.

---
 arch/mips64/mm/fault.c       | 51 ++++++++++++++++++++++++++++++++++++++------
 include/asm-mips64/pgtable.h |  7 ++++++
 2 files changed, 51 insertions(+), 7 deletions(-)

diff --git a/arch/mips64/mm/fault.c b/arch/mips64/mm/fault.c
index 42e810176..a070ae50c 100644
--- a/arch/mips64/mm/fault.c
+++ b/arch/mips64/mm/fault.c
@@ -84,6 +84,18 @@ do_page_fault(struct pt_regs *regs, unsigned long write, unsigned long address)
 	unsigned long fixup;
 	siginfo_t info;
 
+	/*
+	 * We fault-in kernel-space virtual memory on-demand. The
+	 * 'reference' page table is init_mm.pgd.
+	 *
+	 * NOTE! We MUST NOT take any locks for this case. We may
+	 * be in an interrupt or a critical region, and should
+	 * only copy the information from the master page table,
+	 * nothing more.
+	 */
+	if (address >= TASK_SIZE)
+		goto vmalloc_fault;
+
 	info.si_code = SEGV_MAPERR;
 	/*
 	 * If we're in an interrupt or have no user
@@ -148,13 +160,7 @@ good_area:
 bad_area:
 	up_read(&mm->mmap_sem);
 
-	/*
-	 * Quickly check for vmalloc range faults.
-	 */
-	if ((!vma) && (address >= VMALLOC_START) && (address < VMALLOC_END)) {
-		printk("Fix vmalloc invalidate fault\n");
-		while(1);
-	}
+bad_area_nosemaphore:
 	if (user_mode(regs)) {
 		tsk->thread.cp0_badvaddr = address;
 		tsk->thread.error_code = write;
@@ -232,4 +238,35 @@ do_sigbus:
 	/* Kernel mode? Handle exceptions or die */
 	if (!user_mode(regs))
 		goto no_context;
+
+	return;
+
+vmalloc_fault:
+	{
+		/*
+		 * Synchronize this task's top level page-table
+		 * with the 'reference' page table.
+		 */
+		int offset = pgd_index(address);
+		pgd_t *pgd, *pgd_k;
+		pmd_t *pmd, *pmd_k;
+
+		pgd = tsk->active_mm->pgd + offset;
+		pgd_k = init_mm.pgd + offset;
+
+		if (!pgd_present(*pgd)) {
+			if (!pgd_present(*pgd_k))
+				goto bad_area_nosemaphore;
+			set_pgd(pgd, *pgd_k);
+			return;
+		}
+
+		pmd = pmd_offset(pgd, address);
+		pmd_k = pmd_offset(pgd_k, address);
+
+		if (pmd_present(*pmd) || !pmd_present(*pmd_k))
+			goto bad_area_nosemaphore;
+		set_pmd(pmd, *pmd_k);
+		return;
+	}
 }
diff --git a/include/asm-mips64/pgtable.h b/include/asm-mips64/pgtable.h
index bd925fd6b..db48fc09e 100644
--- a/include/asm-mips64/pgtable.h
+++ b/include/asm-mips64/pgtable.h
@@ -313,6 +313,13 @@ extern inline void pte_clear(pte_t *ptep)
 	set_pte(ptep, __pte(0));
 }
 
+/*
+ * (pmds are folded into pgds so this doesnt get actually called,
+ * but the define is needed for a generic inline function.)
+ */
+#define set_pmd(pmdptr, pmdval) (*(pmdptr) = pmdval)
+#define set_pgd(pgdptr, pgdval) (*(pgdptr) = pgdval)
+
 /*
  * Empty pmd entries point to the invalid_pte_table.
  */
-- 
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