From: Will Deacon <will.deacon@xxxxxxx>
[ Upstream commit a25ffd3a6302a67814280274d8f1aa4ae2ea4b59 ]
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@xxxxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
---
arch/arm64/kernel/process.c | 8 ++--
arch/arm64/kernel/traps.c | 74 ++-----------------------------------
2 files changed, 6 insertions(+), 76 deletions(-)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index e917d119490ce..6b073a31eec1c 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -182,11 +182,9 @@ 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 5962badb33462..ac73d8d8cd81d 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -52,55 +52,9 @@ static const char *handler[]= {
int show_unhandled_signals = 0;
-/*
- * 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)
@@ -174,10 +128,8 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
skip = !!regs;
printk("Call trace:\n");
- while (1) {
+ do {
unsigned long where = frame.pc;
- unsigned long stack;
- int ret;
/* skip until specified stack frame */
if (!skip) {
@@ -193,25 +145,7 @@ static 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;
- stack = frame.sp;
- if (in_exception_text(where)) {
- /*
- * If we switched to the irq_stack before calling this
- * exception handler, then the pt_regs will be on the
- * task stack. The easiest way to tell is if the large
- * pt_regs would overlap with the end of the irq_stack.
- */
- if (stack < irq_stack_ptr &&
- (stack + sizeof(struct pt_regs)) > irq_stack_ptr)
- stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
-
- dump_mem("", "Exception stack", stack,
- stack + sizeof(struct pt_regs));
- }
- }
+ } while (!unwind_frame(tsk, &frame));
}
void show_stack(struct task_struct *tsk, unsigned long *sp)
@@ -248,8 +182,6 @@ static int __die(const char *str, int err, struct thread_info *thread,
TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
if (!user_mode(regs)) {
- dump_mem(KERN_EMERG, "Stack: ", regs->sp,
- THREAD_SIZE + (unsigned long)task_stack_page(tsk));
dump_backtrace(regs, tsk);
dump_instr(KERN_EMERG, regs);
}
--
2.25.1
