Merge commit 'v2.6.27-rc6' into x86/iommu

2 files changed, 63 insertions, 2 deletions

diff --git a/arch/avr32/kernel/asm-offsets.c b/arch/avr32/kernel/asm-offsets.c
index e4796c67a831..d6a8193a1d2f 100644
--- a/arch/avr32/kernel/asm-offsets.c
+++ b/arch/avr32/kernel/asm-offsets.c
@@ -4,6 +4,8 @@
  * to extract and format the required data.
  */
 
+#include <linux/mm.h>
+#include <linux/sched.h>
 #include <linux/thread_info.h>
 #include <linux/kbuild.h>
 
@@ -17,4 +19,8 @@ void foo(void)
 	OFFSET(TI_rar_saved, thread_info, rar_saved);
 	OFFSET(TI_rsr_saved, thread_info, rsr_saved);
 	OFFSET(TI_restart_block, thread_info, restart_block);
+	BLANK();
+	OFFSET(TSK_active_mm, task_struct, active_mm);
+	BLANK();
+	OFFSET(MM_pgd, mm_struct, pgd);
 }
diff --git a/arch/avr32/kernel/entry-avr32b.S b/arch/avr32/kernel/entry-avr32b.S
index 2b398cae110c..33d49377b8be 100644
--- a/arch/avr32/kernel/entry-avr32b.S
+++ b/arch/avr32/kernel/entry-avr32b.S
@@ -334,9 +334,64 @@ save_full_context_ex:
 
 	/* Low-level exception handlers */
 handle_critical:
+	/*
+	 * AT32AP700x errata:
+	 *
+	 * After a Java stack overflow or underflow trap, any CPU
+	 * memory access may cause erratic behavior. This will happen
+	 * when the four least significant bits of the JOSP system
+	 * register contains any value between 9 and 15 (inclusive).
+	 *
+	 * Possible workarounds:
+	 *   - Don't use the Java Extension Module
+	 *   - Ensure that the stack overflow and underflow trap
+	 *     handlers do not do any memory access or trigger any
+	 *     exceptions before the overflow/underflow condition is
+	 *     cleared (by incrementing or decrementing the JOSP)
+	 *   - Make sure that JOSP does not contain any problematic
+	 *     value before doing any exception or interrupt
+	 *     processing.
+	 *   - Set up a critical exception handler which writes a
+	 *     known-to-be-safe value, e.g. 4, to JOSP before doing
+	 *     any further processing.
+	 *
+	 * We'll use the last workaround for now since we cannot
+	 * guarantee that user space processes don't use Java mode.
+	 * Non-well-behaving userland will be terminated with extreme
+	 * prejudice.
+	 */
+#ifdef CONFIG_CPU_AT32AP700X
+	/*
+	 * There's a chance we can't touch memory, so temporarily
+	 * borrow PTBR to save the stack pointer while we fix things
+	 * up...
+	 */
+	mtsr	SYSREG_PTBR, sp
+	mov	sp, 4
+	mtsr	SYSREG_JOSP, sp
+	mfsr	sp, SYSREG_PTBR
+	sub	pc, -2
+
+	/* Push most of pt_regs on stack. We'll do the rest later */
 	sub	sp, 4
-	stmts	--sp, r0-lr
-	rcall	save_full_context_ex
+	pushm	r0-r12
+
+	/* PTBR mirrors current_thread_info()->task->active_mm->pgd */
+	get_thread_info r0
+	ld.w	r1, r0[TI_task]
+	ld.w	r2, r1[TSK_active_mm]
+	ld.w	r3, r2[MM_pgd]
+	mtsr	SYSREG_PTBR, r3
+#else
+	sub	sp, 4
+	pushm	r0-r12
+#endif
+	sub	r0, sp, -(14 * 4)
+	mov	r1, lr
+	mfsr	r2, SYSREG_RAR_EX
+	mfsr	r3, SYSREG_RSR_EX
+	pushm	r0-r3
+
 	mfsr	r12, SYSREG_ECR
 	mov	r11, sp
 	rcall	do_critical_exception