[RFC PATCH v1 22/31] ARC: Page Fault handling (incl uaccess fixup)
This includes recent changes to make handler "retry" and/or "killable"
The killable (early exit) logic is loosely based on how SH implements it
return if SIGKILL + either of VM_FAULT_OOM or VM_FAULT_RETRY
which is different from Hexagon implementation which would NOT early
exit for
SIGKILL + VM_FAULT_OOM + !VM_FAULT_RETRY
Signed-off-by: Vineet Gupta
---
arch/arc/mm/extable.c | 26 ++
arch/arc/mm/fault.c | 228 +
2 files changed, 254 insertions(+), 0 deletions(-)
create mode 100644 arch/arc/mm/extable.c
create mode 100644 arch/arc/mm/fault.c
diff --git a/arch/arc/mm/extable.c b/arch/arc/mm/extable.c
new file mode 100644
index 000..f05b677
--- /dev/null
+++ b/arch/arc/mm/extable.c
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Borrowed heavily from MIPS
+ */
+
+#include
+#include
+
+int fixup_exception(struct pt_regs *regs)
+{
+ const struct exception_table_entry *fixup;
+
+ fixup = search_exception_tables(instruction_pointer(regs));
+ if (fixup) {
+ regs->ret = fixup->fixup;
+
+ return 1;
+ }
+
+ return 0;
+}
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
new file mode 100644
index 000..af55aab
--- /dev/null
+++ b/arch/arc/mm/fault.c
@@ -0,0 +1,228 @@
+/* Page Fault Handling for ARC (TLB Miss / ProtV)
+ *
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+static int handle_vmalloc_fault(struct mm_struct *mm, unsigned long address)
+{
+ /*
+* Synchronize this task's top level page-table
+* with the 'reference' page table.
+*/
+ pgd_t *pgd, *pgd_k;
+ pud_t *pud, *pud_k;
+ pmd_t *pmd, *pmd_k;
+
+ pgd = pgd_offset_fast(mm, address);
+ pgd_k = pgd_offset_k(address);
+
+ if (!pgd_present(*pgd_k))
+ goto bad_area;
+
+ pud = pud_offset(pgd, address);
+ pud_k = pud_offset(pgd_k, address);
+ if (!pud_present(*pud_k))
+ goto bad_area;
+
+ pmd = pmd_offset(pud, address);
+ pmd_k = pmd_offset(pud_k, address);
+ if (!pmd_present(*pmd_k))
+ goto bad_area;
+
+ set_pmd(pmd, *pmd_k);
+
+ /* XXX: create the TLB entry here */
+ return 0;
+
+bad_area:
+ return 1;
+}
+
+void do_page_fault(struct pt_regs *regs, int write, unsigned long address,
+ unsigned long cause_code)
+{
+ struct vm_area_struct *vma = NULL;
+ struct task_struct *tsk = current;
+ struct mm_struct *mm = tsk->mm;
+ siginfo_t info;
+ int fault, ret;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+ (write ? FAULT_FLAG_WRITE : 0);
+
+ /*
+* 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 >= VMALLOC_START && address <= VMALLOC_END) {
+ ret = handle_vmalloc_fault(mm, address);
+ if (unlikely(ret))
+ goto bad_area_nosemaphore;
+ else
+ return;
+ }
+
+ info.si_code = SEGV_MAPERR;
+
+ /*
+* If we're in an interrupt or have no user
+* context, we must not take the fault..
+*/
+ if (in_atomic() || !mm)
+ goto no_context;
+
+retry:
+ down_read(>mmap_sem);
+ vma = find_vma(mm, address);
+ if (!vma)
+ goto bad_area;
+ if (vma->vm_start <= address)
+ goto good_area;
+ if (!(vma->vm_flags & VM_GROWSDOWN))
+ goto bad_area;
+ if (expand_stack(vma, address))
+ goto bad_area;
+
+ /*
+* Ok, we have a good vm_area for this memory access, so
+* we can handle it..
+*/
+good_area:
+ info.si_code = SEGV_ACCERR;
+
+ /* Handle protection violation, execute on heap or stack */
+
+ if (cause_code == ((ECR_V_PROTV << 16) | ECR_C_PROTV_INST_FETCH))
+ goto bad_area;
+
+ if (write) {
+ if (!(vma->vm_flags & VM_WRITE))
+ goto
[RFC PATCH v1 22/31] ARC: Page Fault handling (incl uaccess fixup)
This includes recent changes to make handler retry and/or killable
The killable (early exit) logic is loosely based on how SH implements it
return if SIGKILL + either of VM_FAULT_OOM or VM_FAULT_RETRY
which is different from Hexagon implementation which would NOT early
exit for
SIGKILL + VM_FAULT_OOM + !VM_FAULT_RETRY
Signed-off-by: Vineet Gupta vgu...@synopsys.com
---
arch/arc/mm/extable.c | 26 ++
arch/arc/mm/fault.c | 228 +
2 files changed, 254 insertions(+), 0 deletions(-)
create mode 100644 arch/arc/mm/extable.c
create mode 100644 arch/arc/mm/fault.c
diff --git a/arch/arc/mm/extable.c b/arch/arc/mm/extable.c
new file mode 100644
index 000..f05b677
--- /dev/null
+++ b/arch/arc/mm/extable.c
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Borrowed heavily from MIPS
+ */
+
+#include linux/module.h
+#include linux/uaccess.h
+
+int fixup_exception(struct pt_regs *regs)
+{
+ const struct exception_table_entry *fixup;
+
+ fixup = search_exception_tables(instruction_pointer(regs));
+ if (fixup) {
+ regs-ret = fixup-fixup;
+
+ return 1;
+ }
+
+ return 0;
+}
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
new file mode 100644
index 000..af55aab
--- /dev/null
+++ b/arch/arc/mm/fault.c
@@ -0,0 +1,228 @@
+/* Page Fault Handling for ARC (TLB Miss / ProtV)
+ *
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include linux/signal.h
+#include linux/interrupt.h
+#include linux/sched.h
+#include linux/errno.h
+#include linux/ptrace.h
+#include linux/version.h
+#include linux/uaccess.h
+#include linux/kdebug.h
+#include asm/pgalloc.h
+
+static int handle_vmalloc_fault(struct mm_struct *mm, unsigned long address)
+{
+ /*
+* Synchronize this task's top level page-table
+* with the 'reference' page table.
+*/
+ pgd_t *pgd, *pgd_k;
+ pud_t *pud, *pud_k;
+ pmd_t *pmd, *pmd_k;
+
+ pgd = pgd_offset_fast(mm, address);
+ pgd_k = pgd_offset_k(address);
+
+ if (!pgd_present(*pgd_k))
+ goto bad_area;
+
+ pud = pud_offset(pgd, address);
+ pud_k = pud_offset(pgd_k, address);
+ if (!pud_present(*pud_k))
+ goto bad_area;
+
+ pmd = pmd_offset(pud, address);
+ pmd_k = pmd_offset(pud_k, address);
+ if (!pmd_present(*pmd_k))
+ goto bad_area;
+
+ set_pmd(pmd, *pmd_k);
+
+ /* XXX: create the TLB entry here */
+ return 0;
+
+bad_area:
+ return 1;
+}
+
+void do_page_fault(struct pt_regs *regs, int write, unsigned long address,
+ unsigned long cause_code)
+{
+ struct vm_area_struct *vma = NULL;
+ struct task_struct *tsk = current;
+ struct mm_struct *mm = tsk-mm;
+ siginfo_t info;
+ int fault, ret;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+ (write ? FAULT_FLAG_WRITE : 0);
+
+ /*
+* 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 = VMALLOC_START address = VMALLOC_END) {
+ ret = handle_vmalloc_fault(mm, address);
+ if (unlikely(ret))
+ goto bad_area_nosemaphore;
+ else
+ return;
+ }
+
+ info.si_code = SEGV_MAPERR;
+
+ /*
+* If we're in an interrupt or have no user
+* context, we must not take the fault..
+*/
+ if (in_atomic() || !mm)
+ goto no_context;
+
+retry:
+ down_read(mm-mmap_sem);
+ vma = find_vma(mm, address);
+ if (!vma)
+ goto bad_area;
+ if (vma-vm_start = address)
+ goto good_area;
+ if (!(vma-vm_flags VM_GROWSDOWN))
+ goto bad_area;
+ if (expand_stack(vma, address))
+ goto bad_area;
+
+ /*
+* Ok, we have a good vm_area for this memory access, so
+* we can handle it..
+*/
+good_area:
+ info.si_code = SEGV_ACCERR;
+
+ /* Handle protection violation, execute on heap or stack */
+
+ if (cause_code == ((ECR_V_PROTV 16) |
