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-rw-r--r--arch/arm/mm/alignment.c56
1 files changed, 41 insertions, 15 deletions
diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index be7c638b648b..cfbcf8b95599 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -22,6 +22,7 @@
#include <linux/sched.h>
#include <linux/uaccess.h>
+#include <asm/system.h>
#include <asm/unaligned.h>
#include "fault.h"
@@ -95,6 +96,33 @@ static const char *usermode_action[] = {
"signal+warn"
};
+/* Return true if and only if the ARMv6 unaligned access model is in use. */
+static bool cpu_is_v6_unaligned(void)
+{
+ return cpu_architecture() >= CPU_ARCH_ARMv6 && (cr_alignment & CR_U);
+}
+
+static int safe_usermode(int new_usermode, bool warn)
+{
+ /*
+ * ARMv6 and later CPUs can perform unaligned accesses for
+ * most single load and store instructions up to word size.
+ * LDM, STM, LDRD and STRD still need to be handled.
+ *
+ * Ignoring the alignment fault is not an option on these
+ * CPUs since we spin re-faulting the instruction without
+ * making any progress.
+ */
+ if (cpu_is_v6_unaligned() && !(new_usermode & (UM_FIXUP | UM_SIGNAL))) {
+ new_usermode |= UM_FIXUP;
+
+ if (warn)
+ printk(KERN_WARNING "alignment: ignoring faults is unsafe on this CPU. Defaulting to fixup mode.\n");
+ }
+
+ return new_usermode;
+}
+
static int alignment_proc_show(struct seq_file *m, void *v)
{
seq_printf(m, "User:\t\t%lu\n", ai_user);
@@ -125,7 +153,7 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer
if (get_user(mode, buffer))
return -EFAULT;
if (mode >= '0' && mode <= '5')
- ai_usermode = mode - '0';
+ ai_usermode = safe_usermode(mode - '0', true);
}
return count;
}
@@ -886,9 +914,16 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (ai_usermode & UM_FIXUP)
goto fixup;
- if (ai_usermode & UM_SIGNAL)
- force_sig(SIGBUS, current);
- else {
+ if (ai_usermode & UM_SIGNAL) {
+ siginfo_t si;
+
+ si.si_signo = SIGBUS;
+ si.si_errno = 0;
+ si.si_code = BUS_ADRALN;
+ si.si_addr = (void __user *)addr;
+
+ force_sig_info(si.si_signo, &si, current);
+ } else {
/*
* We're about to disable the alignment trap and return to
* user space. But if an interrupt occurs before actually
@@ -926,20 +961,11 @@ static int __init alignment_init(void)
return -ENOMEM;
#endif
- /*
- * ARMv6 and later CPUs can perform unaligned accesses for
- * most single load and store instructions up to word size.
- * LDM, STM, LDRD and STRD still need to be handled.
- *
- * Ignoring the alignment fault is not an option on these
- * CPUs since we spin re-faulting the instruction without
- * making any progress.
- */
- if (cpu_architecture() >= CPU_ARCH_ARMv6 && (cr_alignment & CR_U)) {
+ if (cpu_is_v6_unaligned()) {
cr_alignment &= ~CR_A;
cr_no_alignment &= ~CR_A;
set_cr(cr_alignment);
- ai_usermode = UM_FIXUP;
+ ai_usermode = safe_usermode(ai_usermode, false);
}
hook_fault_code(1, do_alignment, SIGBUS, BUS_ADRALN,
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