On Mon, Sep 08, 2025 at 01:16:45PM +0100, Will Deacon wrote:

On Thu, Jul 17, 2025 at 11:47:43PM +0000, Mostafa Saleh wrote:

quoted

Similar to the kernel panic, where the instruction code is printed,
we can do the same for hypervisor panics.

This patch does that only in case of “CONFIG_NVHE_EL2_DEBUG” or nvhe.

The next patch adds support for pKVM.

Also, remove the hardcoded argument dump_kernel_instr().

Signed-off-by: Mostafa Saleh <smostafa@google.com>
---
 arch/arm64/include/asm/traps.h |  1 +
 arch/arm64/kernel/traps.c      | 20 +++++++++++++-------
 arch/arm64/kvm/handle_exit.c   |  5 +++++
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
index 82cf1f879c61..0d7e86a95d62 100644
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h

@@ -30,6 +30,7 @@ void arm64_force_sig_mceerr(int code, unsigned long far, short lsb, const char *
 void arm64_force_sig_ptrace_errno_trap(int errno, unsigned long far, const char *str);
 
 int early_brk64(unsigned long addr, unsigned long esr, struct pt_regs *regs);
+void dump_instr(unsigned long addr);
 
 /*
  * Move regs->pc to next instruction and do necessary setup before it

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 9bfa5c944379..d692c05e3686 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c

@@ -149,15 +149,11 @@ pstate_check_t * const aarch32_opcode_cond_checks[16] = {
 
 int show_unhandled_signals = 0;
 
-static void dump_kernel_instr(const char *lvl, struct pt_regs *regs)
+void dump_instr(unsigned long addr)
 {
-	unsigned long addr = instruction_pointer(regs);
 	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 	int i;
 
-	if (user_mode(regs))
-		return;
-
 	for (i = -4; i < 1; i++) {
 		unsigned int val, bad;

I'm a little worried that this function might be used to try and dump
instructions from userspace now that it just takes an address.

Maybe we could:

  - Keep the name unchanged, e.g. void dump_kernel_instr(unsigned long kaddr)
  - Inline the user_mode(regs) and instruction_pointer(regs) calls into
    __die()
  - Check is_ttbr1_addr(kaddr) in dump_kernel_instr()

WDYT?

Makes sense, I will do that and respin v2.

Thanks,
Mostafa

Will