add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/arch/xtensa/mm/fault.c
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@@ -20,7 +20,6 @@
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 #include <asm/mmu_context.h>
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 #include <asm/cacheflush.h>
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 #include <asm/hardirq.h>
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-#include <asm/pgalloc.h>
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 DEFINE_PER_CPU(unsigned long, asid_cache) = ASID_USER_FIRST;
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 void bad_page_fault(struct pt_regs*, unsigned long, int);
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@@ -43,7 +42,7 @@
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 	int is_write, is_exec;
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 	vm_fault_t fault;
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-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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+	unsigned int flags = FAULT_FLAG_DEFAULT;
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 	code = SEGV_MAPERR;
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..
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@@ -73,8 +72,11 @@
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 	if (user_mode(regs))
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 		flags |= FAULT_FLAG_USER;
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+
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+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
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+
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 retry:
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-	down_read(&mm->mmap_sem);
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+	mmap_read_lock(mm);
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 	vma = find_vma(mm, address);
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 	if (!vma)
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@@ -108,10 +110,13 @@
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 	 * make sure we exit gracefully rather than endlessly redo
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 	 * the fault.
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 	 */
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-	fault = handle_mm_fault(vma, address, flags);
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+	fault = handle_mm_fault(vma, address, flags, regs);
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-	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
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+	if (fault_signal_pending(fault, regs)) {
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+		if (!user_mode(regs))
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+			goto bad_page_fault;
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 		return;
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+	}
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 	if (unlikely(fault & VM_FAULT_ERROR)) {
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 		if (fault & VM_FAULT_OOM)
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@@ -123,15 +128,10 @@
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 		BUG();
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 	}
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 	if (flags & FAULT_FLAG_ALLOW_RETRY) {
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-		if (fault & VM_FAULT_MAJOR)
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-			current->maj_flt++;
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-		else
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-			current->min_flt++;
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 		if (fault & VM_FAULT_RETRY) {
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-			flags &= ~FAULT_FLAG_ALLOW_RETRY;
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 			flags |= FAULT_FLAG_TRIED;
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-			 /* No need to up_read(&mm->mmap_sem) as we would
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+			 /* No need to mmap_read_unlock(mm) as we would
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 			 * have already released it in __lock_page_or_retry
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 			 * in mm/filemap.c.
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 			 */
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@@ -140,24 +140,18 @@
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 		}
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 	}
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-	up_read(&mm->mmap_sem);
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-	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
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-	if (flags & VM_FAULT_MAJOR)
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-		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
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-	else
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-		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
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-
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+	mmap_read_unlock(mm);
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 	return;
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 	/* Something tried to access memory that isn't in our memory map..
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 	 * Fix it, but check if it's kernel or user first..
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 	 */
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 bad_area:
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-	up_read(&mm->mmap_sem);
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+	mmap_read_unlock(mm);
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 	if (user_mode(regs)) {
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 		current->thread.bad_vaddr = address;
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 		current->thread.error_code = is_write;
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-		force_sig_fault(SIGSEGV, code, (void *) address, current);
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+		force_sig_fault(SIGSEGV, code, (void *) address);
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 		return;
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 	}
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 	bad_page_fault(regs, address, SIGSEGV);
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@@ -168,7 +162,7 @@
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 	 * us unable to handle the page fault gracefully.
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 	 */
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 out_of_memory:
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-	up_read(&mm->mmap_sem);
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+	mmap_read_unlock(mm);
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 	if (!user_mode(regs))
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 		bad_page_fault(regs, address, SIGKILL);
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 	else
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@@ -176,13 +170,13 @@
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 	return;
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 do_sigbus:
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-	up_read(&mm->mmap_sem);
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+	mmap_read_unlock(mm);
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 	/* Send a sigbus, regardless of whether we were in kernel
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 	 * or user mode.
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 	 */
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 	current->thread.bad_vaddr = address;
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-	force_sig_fault(SIGBUS, BUS_ADRERR, (void *) address, current);
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+	force_sig_fault(SIGBUS, BUS_ADRERR, (void *) address);
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 	/* Kernel mode? Handle exceptions or die */
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 	if (!user_mode(regs))
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@@ -197,6 +191,8 @@
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 		struct mm_struct *act_mm = current->active_mm;
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 		int index = pgd_index(address);
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 		pgd_t *pgd, *pgd_k;
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+		p4d_t *p4d, *p4d_k;
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+		pud_t *pud, *pud_k;
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 		pmd_t *pmd, *pmd_k;
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 		pte_t *pte_k;
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@@ -211,8 +207,18 @@
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 		pgd_val(*pgd) = pgd_val(*pgd_k);
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-		pmd = pmd_offset(pgd, address);
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-		pmd_k = pmd_offset(pgd_k, address);
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+		p4d = p4d_offset(pgd, address);
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+		p4d_k = p4d_offset(pgd_k, address);
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+		if (!p4d_present(*p4d) || !p4d_present(*p4d_k))
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+			goto bad_page_fault;
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+
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+		pud = pud_offset(p4d, address);
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+		pud_k = pud_offset(p4d_k, address);
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+		if (!pud_present(*pud) || !pud_present(*pud_k))
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+			goto bad_page_fault;
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+
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+		pmd = pmd_offset(pud, address);
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+		pmd_k = pmd_offset(pud_k, address);
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 		if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
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 			goto bad_page_fault;
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