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authorHaavard Skinnemoen <hskinnemoen@atmel.com>2007-11-28 15:04:01 +0100
committerHaavard Skinnemoen <hskinnemoen@atmel.com>2007-12-07 14:54:46 +0100
commit2507bc1338e43eadfef5b604d2c47e4f8180718f (patch)
tree4bc3c14114ba96efb8e9e4f2c0925fb92b669a19 /include/asm-avr32
parent8dfe8f29cd371affcc3c6b35658dc4bd95ee7b61 (diff)
[AVR32] Follow the rules when dealing with the OCD system
The current debug trap handling code does a number of things that are illegal according to the AVR32 Architecture manual. Most importantly, it may try to schedule from Debug Mode, thus clearing the D bit, which can lead to "undefined behaviour". It seems like this works in most cases, but several people have observed somewhat unstable behaviour when debugging programs, including soft lockups. So there's definitely something which is not right with the existing code. The new code will never schedule from Debug mode, it will always exit Debug mode with a "retd" instruction, and if something not running in Debug mode needs to do something debug-related (like doing a single step), it will enter debug mode through a "breakpoint" instruction. The monitor code will then return directly to user space, bypassing its own saved registers if necessary (since we don't actually care about the trapped context, only the one that came before.) This adds three instructions to the common exception handling code, including one branch. It does not touch super-hot paths like the TLB miss handler. Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Diffstat (limited to 'include/asm-avr32')
-rw-r--r--include/asm-avr32/processor.h3
-rw-r--r--include/asm-avr32/thread_info.h12
2 files changed, 11 insertions, 4 deletions
diff --git a/include/asm-avr32/processor.h b/include/asm-avr32/processor.h
index 6a64833756a..a52576b25af 100644
--- a/include/asm-avr32/processor.h
+++ b/include/asm-avr32/processor.h
@@ -139,6 +139,9 @@ extern void show_regs_log_lvl(struct pt_regs *regs, const char *log_lvl);
extern void show_stack_log_lvl(struct task_struct *tsk, unsigned long sp,
struct pt_regs *regs, const char *log_lvl);
+#define task_pt_regs(p) \
+ ((struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1)
+
#define KSTK_EIP(tsk) ((tsk)->thread.cpu_context.pc)
#define KSTK_ESP(tsk) ((tsk)->thread.cpu_context.ksp)
diff --git a/include/asm-avr32/thread_info.h b/include/asm-avr32/thread_info.h
index 67e7aae89e1..184b574289b 100644
--- a/include/asm-avr32/thread_info.h
+++ b/include/asm-avr32/thread_info.h
@@ -25,6 +25,11 @@ struct thread_info {
unsigned long flags; /* low level flags */
__u32 cpu;
__s32 preempt_count; /* 0 => preemptable, <0 => BUG */
+ __u32 rar_saved; /* return address... */
+ __u32 rsr_saved; /* ...and status register
+ saved by debug handler
+ when setting up
+ trampoline */
struct restart_block restart_block;
__u8 supervisor_stack[0];
};
@@ -78,8 +83,8 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
#define TIF_POLLING_NRFLAG 3 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
-#define TIF_BREAKPOINT 4 /* true if we should break after return */
-#define TIF_SINGLE_STEP 5 /* single step after next break */
+#define TIF_BREAKPOINT 4 /* enter monitor mode on return */
+#define TIF_SINGLE_STEP 5 /* single step in progress */
#define TIF_MEMDIE 6
#define TIF_RESTORE_SIGMASK 7 /* restore signal mask in do_signal */
#define TIF_CPU_GOING_TO_SLEEP 8 /* CPU is entering sleep 0 mode */
@@ -89,7 +94,6 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
-#define _TIF_BREAKPOINT (1 << TIF_BREAKPOINT)
#define _TIF_SINGLE_STEP (1 << TIF_SINGLE_STEP)
#define _TIF_MEMDIE (1 << TIF_MEMDIE)
#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
@@ -108,6 +112,6 @@ static inline struct thread_info *current_thread_info(void)
/* work to do on any return to userspace */
#define _TIF_ALLWORK_MASK (_TIF_WORK_MASK | (1 << TIF_SYSCALL_TRACE))
/* work to do on return from debug mode */
-#define _TIF_DBGWORK_MASK (_TIF_WORK_MASK | (1 << TIF_SINGLE_STEP))
+#define _TIF_DBGWORK_MASK (_TIF_WORK_MASK & ~(1 << TIF_BREAKPOINT))
#endif /* __ASM_AVR32_THREAD_INFO_H */