arm64: process: dump memory around registers when displaying regs

A port of 8608d7c4418c75841c562a90cddd9beae5798a48 to ARM64.  Both the
original code and this port are limited to dumping kernel addresses, so
don't bother if the registers are from a userspace process.

Change-Id: Idc76804c54efaaeb70311cbb500c54db6dac4525
Signed-off-by: Greg Hackmann <ghackmann@google.com>

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index f75b540bc3b4b0daae4a8773cd0eddf1a86a90aa..62068ded1e906fbadb505e29a61cc67b064148d9 100644 (file)
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -164,6 +164,70 @@ void machine_restart(char *cmd)
        while (1);
 }
 
+/*
+ * 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;
+       unsigned int i;
+
+       fs = get_fs();
+       set_fs(KERNEL_DS);
+       show_data(regs->pc - nbytes, nbytes * 2, "PC");
+       show_data(regs->regs[30] - nbytes, nbytes * 2, "LR");
+       show_data(regs->sp - nbytes, nbytes * 2, "SP");
+       for (i = 0; i < 30; i++) {
+               char name[4];
+               snprintf(name, sizeof(name), "X%u", i);
+               show_data(regs->regs[i] - nbytes, nbytes * 2, name);
+       }
+       set_fs(fs);
+}
+
 void __show_regs(struct pt_regs *regs)
 {
        int i, top_reg;
@@ -190,6 +254,8 @@ void __show_regs(struct pt_regs *regs)
                if (i % 2 == 0)
                        printk("\n");
        }
+       if (!user_mode(regs))
+               show_extra_register_data(regs, 128);
        printk("\n");
 }