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authorBernd Schmidt <bernds_cb1@t-online.de>2008-05-07 11:41:26 +0800
committerBryan Wu <cooloney@kernel.org>2008-05-07 11:41:26 +0800
commit0893f1250f87e0a832f47bb60fb69ed0d52be7a3 (patch)
tree96dbea09cc618f4e6c4db2a671de215ba6b9784b
parent8513c42edb3f1c91a8418fae11846c87cf7b8581 (diff)
[Blackfin] arch: fix gdb testing regression
When transferring to IRQ5 from an exception, save SYSCFG in memory across the transfer and clear the trace bit. When we get a single step exception, check whether we can safely clear the trace bit in SYSCFG. We can (and should) clear it after the first instruction of the interrupt handler; the first insn saves SYSCFG to the stack in all handlers. Signed-off-by: Bernd Schmidt <bernds_cb1@t-online.de> Signed-off-by: Bryan Wu <cooloney@kernel.org>
-rw-r--r--arch/blackfin/mach-common/entry.S108
-rw-r--r--include/asm-blackfin/entry.h5
-rw-r--r--include/asm-blackfin/mach-common/context.S5
3 files changed, 87 insertions, 31 deletions
diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index 7365a17a6a8..038f70e0be6 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -151,26 +151,62 @@ ENTRY(_ex_soft_bp)
ENDPROC(_ex_soft_bp)
ENTRY(_ex_single_step)
+ /* If we just returned from an interrupt, the single step event is
+ for the RTI instruction. */
r7 = retx;
r6 = reti;
cc = r7 == r6;
- if cc jump _bfin_return_from_exception
- r7 = syscfg;
- bitclr (r7, 0);
- syscfg = R7;
+ if cc jump _bfin_return_from_exception;
+ /* If we were in user mode, do the single step normally. */
p5.l = lo(IPEND);
p5.h = hi(IPEND);
r6 = [p5];
- cc = bittst(r6, 5);
- if !cc jump _ex_trap_c;
- p4.l = lo(EVT5);
- p4.h = hi(EVT5);
- r6.h = _exception_to_level5;
- r6.l = _exception_to_level5;
- r7 = [p4];
- cc = r6 == r7;
- if !cc jump _ex_trap_c;
+ r7 = 0xffe0 (z);
+ r7 = r7 & r6;
+ cc = r7 == 0;
+ if !cc jump 1f;
+
+ /* Single stepping only a single instruction, so clear the trace
+ * bit here. */
+ r7 = syscfg;
+ bitclr (r7, 0);
+ syscfg = R7;
+ jump _ex_trap_c;
+
+1:
+ /*
+ * We were in an interrupt handler. By convention, all of them save
+ * SYSCFG with their first instruction, so by checking whether our
+ * RETX points at the entry point, we can determine whether to allow
+ * a single step, or whether to clear SYSCFG.
+ *
+ * First, find out the interrupt level and the event vector for it.
+ */
+ p5.l = lo(EVT0);
+ p5.h = hi(EVT0);
+ p5 += -4;
+2:
+ r7 = rot r7 by -1;
+ p5 += 4;
+ if !cc jump 2b;
+
+ /* What we actually do is test for the _second_ instruction in the
+ * IRQ handler. That way, if there are insns following the restore
+ * of SYSCFG after leaving the handler, we will not turn off SYSCFG
+ * for them. */
+
+ r7 = [p5];
+ r7 += 2;
+ r6 = RETX;
+ cc = R7 == R6;
+ if !cc jump _bfin_return_from_exception;
+
+ r7 = syscfg;
+ bitclr (r7, 0);
+ syscfg = R7;
+
+ /* Fall through to _bfin_return_from_exception. */
ENDPROC(_ex_single_step)
ENTRY(_bfin_return_from_exception)
@@ -234,20 +270,26 @@ ENTRY(_ex_trap_c)
p5.l = _saved_icplb_fault_addr;
[p5] = r7;
- p4.l = __retx;
- p4.h = __retx;
+ p4.l = _excpt_saved_stuff;
+ p4.h = _excpt_saved_stuff;
+
r6 = retx;
[p4] = r6;
- p4.l = lo(SAFE_USER_INSTRUCTION);
- p4.h = hi(SAFE_USER_INSTRUCTION);
- retx = p4;
+
+ r6 = SYSCFG;
+ [p4 + 4] = r6;
+ BITCLR(r6, 0);
+ SYSCFG = r6;
/* Disable all interrupts, but make sure level 5 is enabled so
* we can switch to that level. Save the old mask. */
cli r6;
- p4.l = _excpt_saved_imask;
- p4.h = _excpt_saved_imask;
- [p4] = r6;
+ [p4 + 8] = r6;
+
+ p4.l = lo(SAFE_USER_INSTRUCTION);
+ p4.h = hi(SAFE_USER_INSTRUCTION);
+ retx = p4;
+
r6 = 0x3f;
sti r6;
@@ -312,16 +354,17 @@ ENDPROC(_double_fault)
ENTRY(_exception_to_level5)
SAVE_ALL_SYS
- p4.l = __retx;
- p4.h = __retx;
+ p4.l = _excpt_saved_stuff;
+ p4.h = _excpt_saved_stuff;
r6 = [p4];
[sp + PT_PC] = r6;
+ r6 = [p4 + 4];
+ [sp + PT_SYSCFG] = r6;
+
/* Restore interrupt mask. We haven't pushed RETI, so this
* doesn't enable interrupts until we return from this handler. */
- p4.l = _excpt_saved_imask;
- p4.h = _excpt_saved_imask;
- r6 = [p4];
+ r6 = [p4 + 8];
sti r6;
/* Restore the hardware error vector. */
@@ -1349,7 +1392,14 @@ ENTRY(_sys_call_table)
.rept NR_syscalls-(.-_sys_call_table)/4
.long _sys_ni_syscall
.endr
-_excpt_saved_imask:
+
+ /*
+ * Used to save the real RETX, IMASK and SYSCFG when temporarily
+ * storing safe values across the transition from exception to IRQ5.
+ */
+_excpt_saved_stuff:
+ .long 0;
+ .long 0;
.long 0;
_exception_stack:
@@ -1363,7 +1413,3 @@ _exception_stack_top:
_last_cplb_fault_retx:
.long 0;
#endif
- /* Used to save the real RETX when temporarily storing a safe
- * return address. */
-__retx:
- .long 0;
diff --git a/include/asm-blackfin/entry.h b/include/asm-blackfin/entry.h
index 562c6d3a323..c4f721e0d00 100644
--- a/include/asm-blackfin/entry.h
+++ b/include/asm-blackfin/entry.h
@@ -17,6 +17,11 @@
#define PF_DTRACE_OFF 1
#define PF_DTRACE_BIT 5
+/*
+ * NOTE! The single-stepping code assumes that all interrupt handlers
+ * start by saving SYSCFG on the stack with their first instruction.
+ */
+
/* This one is used for exceptions, emulation, and NMI. It doesn't push
RETI and doesn't do cli. */
#define SAVE_ALL_SYS save_context_no_interrupts
diff --git a/include/asm-blackfin/mach-common/context.S b/include/asm-blackfin/mach-common/context.S
index fd0ebe1862b..c0e630edfb9 100644
--- a/include/asm-blackfin/mach-common/context.S
+++ b/include/asm-blackfin/mach-common/context.S
@@ -28,6 +28,11 @@
*/
/*
+ * NOTE! The single-stepping code assumes that all interrupt handlers
+ * start by saving SYSCFG on the stack with their first instruction.
+ */
+
+/*
* Code to save processor context.
* We even save the register which are preserved by a function call
* - r4, r5, r6, r7, p3, p4, p5