arm64: Correctly report LR and SP for compat tasks

When a task crashes and we print debugging information, ensure that
compat tasks show the actual AArch32 LR and SP registers rather than the
AArch64 ones.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 16 insertions, 5 deletions

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 57fb55c44c90..7ae8a1f00c3c 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -143,15 +143,26 @@ void machine_restart(char *cmd)
 
 void __show_regs(struct pt_regs *regs)
 {
-        int i;
+        int i, top_reg;
+        u64 lr, sp;
+
+        if (compat_user_mode(regs)) {
+                lr = regs->compat_lr;
+                sp = regs->compat_sp;
+                top_reg = 12;
+        } else {
+                lr = regs->regs[30];
+                sp = regs->sp;
+                top_reg = 29;
+        }
 
         show_regs_print_info(KERN_DEFAULT);
         print_symbol("PC is at %s\n", instruction_pointer(regs));
-        print_symbol("LR is at %s\n", regs->regs[30]);
+        print_symbol("LR is at %s\n", lr);
         printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
-               regs->pc, regs->regs[30], regs->pstate);
-        printk("sp : %016llx\n", regs->sp);
-        for (i = 29; i >= 0; i--) {
+               regs->pc, lr, regs->pstate);
+        printk("sp : %016llx\n", sp);
+        for (i = top_reg; i >= 0; i--) {
                 printk("x%-2d: %016llx ", i, regs->regs[i]);
                 if (i % 2 == 0)
                         printk("\n");