Blackfin: improve double fault debug handling

Since the hardware only provides reporting for the last exception handled,
and the values are valid only when executing the exception handler, we
need to save the context for reporting at a later point.  While we do this
for one exception, it doesn't work properly when handling a second one as
the original exception is clobbered by the double fault.  So when double
fault debugging is enabled, create a dedicated shadow of these values and
save/restore out of there.  Now the crash report properly displays the
first exception as well as the second one.

Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

2 files changed, 17 insertions, 13 deletions

diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index cbc5b6d1ed06..4e8e3fe0ba1c 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -326,8 +326,6 @@ ENTRY(_ex_trap_c)
 	[p4] = r7;
 	csync;
 
-#ifndef CONFIG_DEBUG_DOUBLEFAULT
-
 	/*
 	 * Save these registers, as they are only valid in exception context
 	 *  (where we are now - as soon as we defer to IRQ5, they can change)
@@ -347,7 +345,10 @@ ENTRY(_ex_trap_c)
 
 	r6 = retx;
 	[p5 + PDA_RETX] = r6;
-#endif
+
+	r6 = SEQSTAT;
+	[p5 + PDA_SEQSTAT] = r6;
+
 	/* Save the state of single stepping */
 	r6 = SYSCFG;
 	[p5 + PDA_SYSCFG] = r6;
@@ -444,6 +445,9 @@ ENTRY(_exception_to_level5)
 	r6 = [p5 + PDA_SYSCFG];
 	[sp + PT_SYSCFG] = r6;
 
+	r6 = [p5 + PDA_SEQSTAT]; /* Read back seqstat */
+	[sp + PT_SEQSTAT] = r6;
+
 	/* Restore the hardware error vector.  */
 	r7.h = _evt_ivhw;
 	r7.l = _evt_ivhw;
@@ -496,7 +500,7 @@ ENTRY(_trap) /* Exception: 4th entry into system event table(supervisor mode)*/
 	 */
 	EX_SCRATCH_REG = sp;
 	GET_PDA_SAFE(sp);
-	sp = [sp + PDA_EXSTACK]
+	sp = [sp + PDA_EXSTACK];
 	/* Try to deal with syscalls quickly.  */
 	[--sp] = ASTAT;
 	[--sp] = (R7:6,P5:4);
@@ -532,18 +536,18 @@ ENTRY(_trap) /* Exception: 4th entry into system event table(supervisor mode)*/
 	p4.l = lo(DCPLB_FAULT_ADDR);
 	p4.h = hi(DCPLB_FAULT_ADDR);
 	r7 = [p4];
-	[p5 + PDA_DCPLB] = r7;
+	[p5 + PDA_DF_DCPLB] = r7;
 
 	p4.l = lo(ICPLB_FAULT_ADDR);
 	p4.h = hi(ICPLB_FAULT_ADDR);
 	r7 = [p4];
-	[p5 + PDA_ICPLB] = r7;
+	[p5 + PDA_DF_ICPLB] = r7;
 
-	r6 = retx;
-	[p5 + PDA_RETX] = r6;
+	r7 = retx;
+	[p5 + PDA_DF_RETX] = r7;
 
 	r7 = SEQSTAT;		/* reason code is in bit 5:0 */
-	[p5 + PDA_SEQSTAT] = r7;
+	[p5 + PDA_DF_SEQSTAT] = r7;
 #else
 	r7 = SEQSTAT;           /* reason code is in bit 5:0 */
 #endif
diff --git a/arch/blackfin/mach-common/head.S b/arch/blackfin/mach-common/head.S
index 66910121fa6f..9c79dfea2a53 100644
--- a/arch/blackfin/mach-common/head.S
+++ b/arch/blackfin/mach-common/head.S
@@ -124,22 +124,22 @@ ENTRY(__start)
 	 * below
 	 */
 	GET_PDA(p0, r0);
-	r6 = [p0 + PDA_RETX];
+	r6 = [p0 + PDA_DF_RETX];
 	p1.l = _init_saved_retx;
 	p1.h = _init_saved_retx;
 	[p1] = r6;
 
-	r6 = [p0 + PDA_DCPLB];
+	r6 = [p0 + PDA_DF_DCPLB];
 	p1.l = _init_saved_dcplb_fault_addr;
 	p1.h = _init_saved_dcplb_fault_addr;
 	[p1] = r6;
 
-	r6 = [p0 + PDA_ICPLB];
+	r6 = [p0 + PDA_DF_ICPLB];
 	p1.l = _init_saved_icplb_fault_addr;
 	p1.h = _init_saved_icplb_fault_addr;
 	[p1] = r6;
 
-	r6 = [p0 + PDA_SEQSTAT];
+	r6 = [p0 + PDA_DF_SEQSTAT];
 	p1.l = _init_saved_seqstat;
 	p1.h = _init_saved_seqstat;
 	[p1] = r6;