[ARM] process: Add display of memory around registers when displaying regs.

This is extremely useful in diagnosing remote crashes, and is based heavily
on original work by <md@google.com>.

Signed-off-by: San Mehat <san@google.com>
Cc: Michael Davidson <md@google.com>
[ARM] process: Use uber-safe probe_kernel_address() to read mem when dumping.

This prevents the dump from taking pagefaults / external aborts.

Signed-off-by: San Mehat <san@google.com>

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 5e1e541..34ea864 100644 (file)
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -251,6 +251,77 @@ void machine_restart(char *cmd)
        arm_pm_restart(reboot_mode, cmd);
 }
 
+/*
+ * dump a block of kernel memory from around the given address
+ */
+static void show_data(unsigned long addr, int nbytes, const char *name)
+{
+       int     i, j;
+       int     nlines;
+       u32     *p;
+
+       /*
+        * don't attempt to dump non-kernel addresses or
+        * values that are probably just small negative numbers
+        */
+       if (addr < PAGE_OFFSET || addr > -256UL)
+               return;
+
+       printk("\n%s: %#lx:\n", name, addr);
+
+       /*
+        * round address down to a 32 bit boundary
+        * and always dump a multiple of 32 bytes
+        */
+       p = (u32 *)(addr & ~(sizeof(u32) - 1));
+       nbytes += (addr & (sizeof(u32) - 1));
+       nlines = (nbytes + 31) / 32;
+
+
+       for (i = 0; i < nlines; i++) {
+               /*
+                * just display low 16 bits of address to keep
+                * each line of the dump < 80 characters
+                */
+               printk("%04lx ", (unsigned long)p & 0xffff);
+               for (j = 0; j < 8; j++) {
+                       u32     data;
+                       if (probe_kernel_address(p, data)) {
+                               printk(" ********");
+                       } else {
+                               printk(" %08x", data);
+                       }
+                       ++p;
+               }
+               printk("\n");
+       }
+}
+
+static void show_extra_register_data(struct pt_regs *regs, int nbytes)
+{
+       mm_segment_t fs;
+
+       fs = get_fs();
+       set_fs(KERNEL_DS);
+       show_data(regs->ARM_pc - nbytes, nbytes * 2, "PC");
+       show_data(regs->ARM_lr - nbytes, nbytes * 2, "LR");
+       show_data(regs->ARM_sp - nbytes, nbytes * 2, "SP");
+       show_data(regs->ARM_ip - nbytes, nbytes * 2, "IP");
+       show_data(regs->ARM_fp - nbytes, nbytes * 2, "FP");
+       show_data(regs->ARM_r0 - nbytes, nbytes * 2, "R0");
+       show_data(regs->ARM_r1 - nbytes, nbytes * 2, "R1");
+       show_data(regs->ARM_r2 - nbytes, nbytes * 2, "R2");
+       show_data(regs->ARM_r3 - nbytes, nbytes * 2, "R3");
+       show_data(regs->ARM_r4 - nbytes, nbytes * 2, "R4");
+       show_data(regs->ARM_r5 - nbytes, nbytes * 2, "R5");
+       show_data(regs->ARM_r6 - nbytes, nbytes * 2, "R6");
+       show_data(regs->ARM_r7 - nbytes, nbytes * 2, "R7");
+       show_data(regs->ARM_r8 - nbytes, nbytes * 2, "R8");
+       show_data(regs->ARM_r9 - nbytes, nbytes * 2, "R9");
+       show_data(regs->ARM_r10 - nbytes, nbytes * 2, "R10");
+       set_fs(fs);
+}
+
 void __show_regs(struct pt_regs *regs)
 {
        unsigned long flags;
@@ -310,6 +381,8 @@ void __show_regs(struct pt_regs *regs)
                printk("Control: %08x%s\n", ctrl, buf);
        }
 #endif
+
+       show_extra_register_data(regs, 128);
 }
 
 void show_regs(struct pt_regs * regs)