aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm/mm/fault.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm/mm/fault.c')
-rw-r--r--arch/arm/mm/fault.c166
1 files changed, 117 insertions, 49 deletions
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index cc8829d7e116..10e06801afb3 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -25,6 +25,19 @@
#include "fault.h"
+/*
+ * Fault status register encodings. We steal bit 31 for our own purposes.
+ */
+#define FSR_LNX_PF (1 << 31)
+#define FSR_WRITE (1 << 11)
+#define FSR_FS4 (1 << 10)
+#define FSR_FS3_0 (15)
+
+static inline int fsr_fs(unsigned int fsr)
+{
+ return (fsr & FSR_FS3_0) | (fsr & FSR_FS4) >> 6;
+}
+
#ifdef CONFIG_MMU
#ifdef CONFIG_KPROBES
@@ -182,18 +195,35 @@ void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
#define VM_FAULT_BADMAP 0x010000
#define VM_FAULT_BADACCESS 0x020000
-static int
+/*
+ * Check that the permissions on the VMA allow for the fault which occurred.
+ * If we encountered a write fault, we must have write permission, otherwise
+ * we allow any permission.
+ */
+static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
+{
+ unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
+
+ if (fsr & FSR_WRITE)
+ mask = VM_WRITE;
+ if (fsr & FSR_LNX_PF)
+ mask = VM_EXEC;
+
+ return vma->vm_flags & mask ? false : true;
+}
+
+static int __kprobes
__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
struct task_struct *tsk)
{
struct vm_area_struct *vma;
- int fault, mask;
+ int fault;
vma = find_vma(mm, addr);
fault = VM_FAULT_BADMAP;
- if (!vma)
+ if (unlikely(!vma))
goto out;
- if (vma->vm_start > addr)
+ if (unlikely(vma->vm_start > addr))
goto check_stack;
/*
@@ -201,47 +231,24 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
* memory access, so we can handle it.
*/
good_area:
- if (fsr & (1 << 11)) /* write? */
- mask = VM_WRITE;
- else
- mask = VM_READ|VM_EXEC|VM_WRITE;
-
- fault = VM_FAULT_BADACCESS;
- if (!(vma->vm_flags & mask))
+ if (access_error(fsr, vma)) {
+ fault = VM_FAULT_BADACCESS;
goto out;
+ }
/*
- * If for any reason at all we couldn't handle
- * the fault, make sure we exit gracefully rather
- * than endlessly redo the fault.
+ * If for any reason at all we couldn't handle the fault, make
+ * sure we exit gracefully rather than endlessly redo the fault.
*/
-survive:
- fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, (fsr & (1 << 11)) ? FAULT_FLAG_WRITE : 0);
- if (unlikely(fault & VM_FAULT_ERROR)) {
- if (fault & VM_FAULT_OOM)
- goto out_of_memory;
- else if (fault & VM_FAULT_SIGBUS)
- return fault;
- BUG();
- }
+ fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, (fsr & FSR_WRITE) ? FAULT_FLAG_WRITE : 0);
+ if (unlikely(fault & VM_FAULT_ERROR))
+ return fault;
if (fault & VM_FAULT_MAJOR)
tsk->maj_flt++;
else
tsk->min_flt++;
return fault;
-out_of_memory:
- if (!is_global_init(tsk))
- goto out;
-
- /*
- * If we are out of memory for pid1, sleep for a while and retry
- */
- up_read(&mm->mmap_sem);
- yield();
- down_read(&mm->mmap_sem);
- goto survive;
-
check_stack:
if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
goto good_area;
@@ -278,6 +285,18 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
goto no_context;
down_read(&mm->mmap_sem);
+ } else {
+ /*
+ * The above down_read_trylock() might have succeeded in
+ * which case, we'll have missed the might_sleep() from
+ * down_read()
+ */
+ might_sleep();
+#ifdef CONFIG_DEBUG_VM
+ if (!user_mode(regs) &&
+ !search_exception_tables(regs->ARM_pc))
+ goto no_context;
+#endif
}
fault = __do_page_fault(mm, addr, fsr, tsk);
@@ -289,6 +308,16 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
return 0;
+ if (fault & VM_FAULT_OOM) {
+ /*
+ * We ran out of memory, call the OOM killer, and return to
+ * userspace (which will retry the fault, or kill us if we
+ * got oom-killed)
+ */
+ pagefault_out_of_memory();
+ return 0;
+ }
+
/*
* If we are in kernel mode at this point, we
* have no context to handle this fault with.
@@ -296,16 +325,6 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (!user_mode(regs))
goto no_context;
- if (fault & VM_FAULT_OOM) {
- /*
- * We ran out of memory, or some other thing
- * happened to us that made us unable to handle
- * the page fault gracefully.
- */
- printk("VM: killing process %s\n", tsk->comm);
- do_group_exit(SIGKILL);
- return 0;
- }
if (fault & VM_FAULT_SIGBUS) {
/*
* We had some memory, but were unable to
@@ -489,10 +508,10 @@ hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *)
asmlinkage void __exception
do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
- const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6);
+ const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
struct siginfo info;
- if (!inf->fn(addr, fsr, regs))
+ if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
return;
printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
@@ -505,9 +524,58 @@ do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
arm_notify_die("", regs, &info, fsr, 0);
}
+
+static struct fsr_info ifsr_info[] = {
+ { do_bad, SIGBUS, 0, "unknown 0" },
+ { do_bad, SIGBUS, 0, "unknown 1" },
+ { do_bad, SIGBUS, 0, "debug event" },
+ { do_bad, SIGSEGV, SEGV_ACCERR, "section access flag fault" },
+ { do_bad, SIGBUS, 0, "unknown 4" },
+ { do_translation_fault, SIGSEGV, SEGV_MAPERR, "section translation fault" },
+ { do_bad, SIGSEGV, SEGV_ACCERR, "page access flag fault" },
+ { do_page_fault, SIGSEGV, SEGV_MAPERR, "page translation fault" },
+ { do_bad, SIGBUS, 0, "external abort on non-linefetch" },
+ { do_bad, SIGSEGV, SEGV_ACCERR, "section domain fault" },
+ { do_bad, SIGBUS, 0, "unknown 10" },
+ { do_bad, SIGSEGV, SEGV_ACCERR, "page domain fault" },
+ { do_bad, SIGBUS, 0, "external abort on translation" },
+ { do_sect_fault, SIGSEGV, SEGV_ACCERR, "section permission fault" },
+ { do_bad, SIGBUS, 0, "external abort on translation" },
+ { do_page_fault, SIGSEGV, SEGV_ACCERR, "page permission fault" },
+ { do_bad, SIGBUS, 0, "unknown 16" },
+ { do_bad, SIGBUS, 0, "unknown 17" },
+ { do_bad, SIGBUS, 0, "unknown 18" },
+ { do_bad, SIGBUS, 0, "unknown 19" },
+ { do_bad, SIGBUS, 0, "unknown 20" },
+ { do_bad, SIGBUS, 0, "unknown 21" },
+ { do_bad, SIGBUS, 0, "unknown 22" },
+ { do_bad, SIGBUS, 0, "unknown 23" },
+ { do_bad, SIGBUS, 0, "unknown 24" },
+ { do_bad, SIGBUS, 0, "unknown 25" },
+ { do_bad, SIGBUS, 0, "unknown 26" },
+ { do_bad, SIGBUS, 0, "unknown 27" },
+ { do_bad, SIGBUS, 0, "unknown 28" },
+ { do_bad, SIGBUS, 0, "unknown 29" },
+ { do_bad, SIGBUS, 0, "unknown 30" },
+ { do_bad, SIGBUS, 0, "unknown 31" },
+};
+
asmlinkage void __exception
-do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
+do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
{
- do_translation_fault(addr, 0, regs);
+ const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
+ struct siginfo info;
+
+ if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
+ return;
+
+ printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
+ inf->name, ifsr, addr);
+
+ info.si_signo = inf->sig;
+ info.si_errno = 0;
+ info.si_code = inf->code;
+ info.si_addr = (void __user *)addr;
+ arm_notify_die("", regs, &info, ifsr, 0);
}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.