aboutsummaryrefslogtreecommitdiffstats
path: root/arch/avr32/kernel/entry-avr32b.S
diff options
context:
space:
mode:
Diffstat (limited to 'arch/avr32/kernel/entry-avr32b.S')
-rw-r--r--arch/avr32/kernel/entry-avr32b.S59
1 files changed, 57 insertions, 2 deletions
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:
334 334
335 /* Low-level exception handlers */ 335 /* Low-level exception handlers */
336handle_critical: 336handle_critical:
337 /*
338 * AT32AP700x errata:
339 *
340 * After a Java stack overflow or underflow trap, any CPU
341 * memory access may cause erratic behavior. This will happen
342 * when the four least significant bits of the JOSP system
343 * register contains any value between 9 and 15 (inclusive).
344 *
345 * Possible workarounds:
346 * - Don't use the Java Extension Module
347 * - Ensure that the stack overflow and underflow trap
348 * handlers do not do any memory access or trigger any
349 * exceptions before the overflow/underflow condition is
350 * cleared (by incrementing or decrementing the JOSP)
351 * - Make sure that JOSP does not contain any problematic
352 * value before doing any exception or interrupt
353 * processing.
354 * - Set up a critical exception handler which writes a
355 * known-to-be-safe value, e.g. 4, to JOSP before doing
356 * any further processing.
357 *
358 * We'll use the last workaround for now since we cannot
359 * guarantee that user space processes don't use Java mode.
360 * Non-well-behaving userland will be terminated with extreme
361 * prejudice.
362 */
363#ifdef CONFIG_CPU_AT32AP700X
364 /*
365 * There's a chance we can't touch memory, so temporarily
366 * borrow PTBR to save the stack pointer while we fix things
367 * up...
368 */
369 mtsr SYSREG_PTBR, sp
370 mov sp, 4
371 mtsr SYSREG_JOSP, sp
372 mfsr sp, SYSREG_PTBR
373 sub pc, -2
374
375 /* Push most of pt_regs on stack. We'll do the rest later */
337 sub sp, 4 376 sub sp, 4
338 stmts --sp, r0-lr 377 pushm r0-r12
339 rcall save_full_context_ex 378
379 /* PTBR mirrors current_thread_info()->task->active_mm->pgd */
380 get_thread_info r0
381 ld.w r1, r0[TI_task]
382 ld.w r2, r1[TSK_active_mm]
383 ld.w r3, r2[MM_pgd]
384 mtsr SYSREG_PTBR, r3
385#else
386 sub sp, 4
387 pushm r0-r12
388#endif
389 sub r0, sp, -(14 * 4)
390 mov r1, lr
391 mfsr r2, SYSREG_RAR_EX
392 mfsr r3, SYSREG_RSR_EX
393 pushm r0-r3
394
340 mfsr r12, SYSREG_ECR 395 mfsr r12, SYSREG_ECR
341 mov r11, sp 396 mov r11, sp
342 rcall do_critical_exception 397 rcall do_critical_exception