MIPS: Print correct PC in trace dump after NMI exception
authorLeonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Tue, 8 Oct 2013 11:39:31 +0000 (12:39 +0100)
committerRalf Baechle <ralf@linux-mips.org>
Tue, 29 Oct 2013 20:25:35 +0000 (21:25 +0100)
An NMI exception delivered from YAMON delivers the PC in ErrorPC
instead of EPC. It's also necessary to clear the Status.BEV
bit for the page fault exception handler to work properly.

[ralf@linux-mips: Let the assembler do the loading of the mask value rather
than the convoluted explicit %hi/%lo manual relocation sequence from the
original patch.]

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6035/
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/6084/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
arch/mips/kernel/genex.S
arch/mips/kernel/traps.c

index 31fa856829cbf2620521317e5247d42b9e3fb087..47d7583cd67ff7de77d5010c89d8bcbba234c2d0 100644 (file)
@@ -374,12 +374,20 @@ NESTED(except_vec_nmi, 0, sp)
 NESTED(nmi_handler, PT_SIZE, sp)
        .set    push
        .set    noat
+       /*
+        * Clear ERL - restore segment mapping
+        * Clear BEV - required for page fault exception handler to work
+        */
+       mfc0    k0, CP0_STATUS
+       ori     k0, k0, ST0_EXL
+       li      k1, ~(ST0_BEV | ST0_ERL)
+       and     k0, k0, k1
+       mtc0    k0, CP0_STATUS
+       _ehb
        SAVE_ALL
        move    a0, sp
        jal     nmi_exception_handler
-       RESTORE_ALL
-       .set    mips3
-       eret
+       /* nmi_exception_handler never returns */
        .set    pop
        END(nmi_handler)
 
index f2ae9cb57ff0b8ee2e191d489b2c08d76303e1d7..a17b6efb8bfe2ddcf8e6c794384e3a61d457acb8 100644 (file)
@@ -330,6 +330,7 @@ void show_regs(struct pt_regs *regs)
 void show_registers(struct pt_regs *regs)
 {
        const int field = 2 * sizeof(unsigned long);
+       mm_segment_t old_fs = get_fs();
 
        __show_regs(regs);
        print_modules();
@@ -344,9 +345,13 @@ void show_registers(struct pt_regs *regs)
                        printk("*HwTLS: %0*lx\n", field, tls);
        }
 
+       if (!user_mode(regs))
+               /* Necessary for getting the correct stack content */
+               set_fs(KERNEL_DS);
        show_stacktrace(current, regs);
        show_code((unsigned int __user *) regs->cp0_epc);
        printk("\n");
+       set_fs(old_fs);
 }
 
 static int regs_to_trapnr(struct pt_regs *regs)
@@ -1488,10 +1493,14 @@ int register_nmi_notifier(struct notifier_block *nb)
 
 void __noreturn nmi_exception_handler(struct pt_regs *regs)
 {
+       char str[100];
+
        raw_notifier_call_chain(&nmi_chain, 0, regs);
        bust_spinlocks(1);
-       printk("NMI taken!!!!\n");
-       die("NMI", regs);
+       snprintf(str, 100, "CPU%d NMI taken, CP0_EPC=%lx\n",
+                smp_processor_id(), regs->cp0_epc);
+       regs->cp0_epc = read_c0_errorepc();
+       die(str, regs);
 }
 
 #define VECTORSPACING 0x100    /* for EI/VI mode */