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>

diff --git a/arch/blackfin/include/asm/pda.h b/arch/blackfin/include/asm/pda.h
index 69b96b40c188ffa0ca0299e97e64b9bceb16ce70..a6f95695731d99ebda1cb14e5823f362f53b5d26 100644 (file)
--- a/arch/blackfin/include/asm/pda.h
+++ b/arch/blackfin/include/asm/pda.h
@@ -61,6 +61,12 @@ struct blackfin_pda {                        /* Per-processor Data Area */
        unsigned long retx;
        unsigned long seqstat;
        unsigned int __nmi_count;       /* number of times NMI asserted on this CPU */
+#ifdef CONFIG_DEBUG_DOUBLEFAULT
+       unsigned long dcplb_doublefault_addr;
+       unsigned long icplb_doublefault_addr;
+       unsigned long retx_doublefault;
+       unsigned long seqstat_doublefault;
+#endif
 };
 
 extern struct blackfin_pda cpu_pda[];

diff --git a/arch/blackfin/kernel/asm-offsets.c b/arch/blackfin/kernel/asm-offsets.c
index 8ad4f2c69961ac44ea17d984fab155ee01e32407..f05d1b99b0ef4a7f2c3c29671f7b0b22a38fe3c2 100644 (file)
--- a/arch/blackfin/kernel/asm-offsets.c
+++ b/arch/blackfin/kernel/asm-offsets.c
@@ -153,6 +153,12 @@ int main(void)
        DEFINE(PDA_ICPLB, offsetof(struct blackfin_pda, icplb_fault_addr));
        DEFINE(PDA_RETX, offsetof(struct blackfin_pda, retx));
        DEFINE(PDA_SEQSTAT, offsetof(struct blackfin_pda, seqstat));
+#ifdef CONFIG_DEBUG_DOUBLEFAULT
+       DEFINE(PDA_DF_DCPLB, offsetof(struct blackfin_pda, dcplb_doublefault_addr));
+       DEFINE(PDA_DF_ICPLB, offsetof(struct blackfin_pda, icplb_doublefault_addr));
+       DEFINE(PDA_DF_SEQSTAT, offsetof(struct blackfin_pda, seqstat_doublefault));
+       DEFINE(PDA_DF_RETX, offsetof(struct blackfin_pda, retx_doublefault));
+#endif
 #ifdef CONFIG_SMP
        /* Inter-core lock (in L2 SRAM) */
        DEFINE(SIZEOF_CORELOCK, sizeof(struct corelock_slot));

diff --git a/arch/blackfin/kernel/traps.c b/arch/blackfin/kernel/traps.c
index 644e35e335537bfd4b1ffda46c19d85b1caeb280..0904430d4137e21619e14169ec42466ad1c0e1bc 100644 (file)
--- a/arch/blackfin/kernel/traps.c
+++ b/arch/blackfin/kernel/traps.c
@@ -229,12 +229,12 @@ asmlinkage void double_fault_c(struct pt_regs *fp)
        if (((long)fp->seqstat &  SEQSTAT_EXCAUSE) == VEC_UNCOV) {
                unsigned int cpu = smp_processor_id();
                char buf[150];
-               decode_address(buf, cpu_pda[cpu].retx);
+               decode_address(buf, cpu_pda[cpu].retx_doublefault);
                printk(KERN_EMERG "While handling exception (EXCAUSE = 0x%x) at %s:\n",
-                       (unsigned int)cpu_pda[cpu].seqstat & SEQSTAT_EXCAUSE, buf);
-               decode_address(buf, cpu_pda[cpu].dcplb_fault_addr);
+                       (unsigned int)cpu_pda[cpu].seqstat_doublefault & SEQSTAT_EXCAUSE, buf);
+               decode_address(buf, cpu_pda[cpu].dcplb_doublefault_addr);
                printk(KERN_NOTICE "   DCPLB_FAULT_ADDR: %s\n", buf);
-               decode_address(buf, cpu_pda[cpu].icplb_fault_addr);
+               decode_address(buf, cpu_pda[cpu].icplb_doublefault_addr);
                printk(KERN_NOTICE "   ICPLB_FAULT_ADDR: %s\n", buf);
 
                decode_address(buf, fp->retx);

diff --git a/arch/blackfin/mach-bf561/secondary.S b/arch/blackfin/mach-bf561/secondary.S
index 35280f06b7b6b0387d475c7921065606e9be4b6a..097550f7b558fa6c0e87e6d99e3619682a6bdb45 100644 (file)
--- a/arch/blackfin/mach-bf561/secondary.S
+++ b/arch/blackfin/mach-bf561/secondary.S
@@ -126,22 +126,22 @@ ENTRY(_coreb_trampoline_start)
         * below
         */
        GET_PDA(p0, r0);
-       r7 = [p0 + PDA_RETX];
+       r7 = [p0 + PDA_DF_RETX];
        p1.l = _init_saved_retx_coreb;
        p1.h = _init_saved_retx_coreb;
        [p1] = r7;
 
-       r7 = [p0 + PDA_DCPLB];
+       r7 = [p0 + PDA_DF_DCPLB];
        p1.l = _init_saved_dcplb_fault_addr_coreb;
        p1.h = _init_saved_dcplb_fault_addr_coreb;
        [p1] = r7;
 
-       r7 = [p0 + PDA_ICPLB];
+       r7 = [p0 + PDA_DF_ICPLB];
        p1.l = _init_saved_icplb_fault_addr_coreb;
        p1.h = _init_saved_icplb_fault_addr_coreb;
        [p1] = r7;
 
-       r7 = [p0 + PDA_SEQSTAT];
+       r7 = [p0 + PDA_DF_SEQSTAT];
        p1.l = _init_saved_seqstat_coreb;
        p1.h = _init_saved_seqstat_coreb;
        [p1] = r7;

diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index cbc5b6d1ed06aaeabda169f7e48a89e04e9128be..4e8e3fe0ba1c14f7e415f0e6ca0e0e1e1ff744ff 100644 (file)
--- 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 66910121fa6fbb785e28a8a785065c38ffafcdbb..9c79dfea2a53b42e94286b0bf52a0b947c29452d 100644 (file)
--- 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;