arm64: traps: Don't print stack or raw PC/LR values in backtraces
Printing raw pointer values in backtraces has potential security
implications and are of questionable value anyway.
This patch follows x86's lead and removes the "Exception stack:" dump
from kernel backtraces, as well as converting PC/LR values to symbols
such as "sysrq_handle_crash+0x20/0x30".
Tested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 2dc0f84..c20896b 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -186,11 +186,9 @@ void __show_regs(struct pt_regs *regs)
}
show_regs_print_info(KERN_DEFAULT);
- print_symbol("PC is at %s\n", instruction_pointer(regs));
- print_symbol("LR is at %s\n", lr);
- printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
- regs->pc, lr, regs->pstate);
- printk("sp : %016llx\n", sp);
+ print_symbol("pc : %s\n", regs->pc);
+ print_symbol("lr : %s\n", lr);
+ printk("sp : %016llx pstate : %08llx\n", sp, regs->pstate);
i = top_reg;
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index a1b7d64..afb6b19 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -58,55 +58,9 @@ static const char *handler[]= {
int show_unhandled_signals = 1;
-/*
- * Dump out the contents of some kernel memory nicely...
- */
-static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
- unsigned long top)
-{
- unsigned long first;
- mm_segment_t fs;
- int i;
-
- /*
- * We need to switch to kernel mode so that we can use __get_user
- * to safely read from kernel space.
- */
- fs = get_fs();
- set_fs(KERNEL_DS);
-
- printk("%s%s(0x%016lx to 0x%016lx)\n", lvl, str, bottom, top);
-
- for (first = bottom & ~31; first < top; first += 32) {
- unsigned long p;
- char str[sizeof(" 12345678") * 8 + 1];
-
- memset(str, ' ', sizeof(str));
- str[sizeof(str) - 1] = '\0';
-
- for (p = first, i = 0; i < (32 / 8)
- && p < top; i++, p += 8) {
- if (p >= bottom && p < top) {
- unsigned long val;
-
- if (__get_user(val, (unsigned long *)p) == 0)
- sprintf(str + i * 17, " %016lx", val);
- else
- sprintf(str + i * 17, " ????????????????");
- }
- }
- printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
- }
-
- set_fs(fs);
-}
-
static void dump_backtrace_entry(unsigned long where)
{
- /*
- * Note that 'where' can have a physical address, but it's not handled.
- */
- print_ip_sym(where);
+ printk(" %pS\n", (void *)where);
}
static void __dump_instr(const char *lvl, struct pt_regs *regs)
@@ -171,10 +125,7 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
skip = !!regs;
printk("Call trace:\n");
- while (1) {
- unsigned long stack;
- int ret;
-
+ do {
/* skip until specified stack frame */
if (!skip) {
dump_backtrace_entry(frame.pc);
@@ -189,17 +140,7 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
*/
dump_backtrace_entry(regs->pc);
}
- ret = unwind_frame(tsk, &frame);
- if (ret < 0)
- break;
- if (in_entry_text(frame.pc)) {
- stack = frame.fp - offsetof(struct pt_regs, stackframe);
-
- if (on_accessible_stack(tsk, stack))
- dump_mem("", "Exception stack", stack,
- stack + sizeof(struct pt_regs));
- }
- }
+ } while (!unwind_frame(tsk, &frame));
put_task_stack(tsk);
}
