Re: [RFC] rust: kernel: Add KUnit tests for ARCH_WARN_ASM bug table emission

Untested thingies for arm64 and s390x.

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 914282016069..3d8a969eab5f 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c

@@ -987,14 +987,13 @@ void do_serror(struct pt_regs *regs, unsigned long esr)
 #ifdef CONFIG_GENERIC_BUG
 int is_valid_bugaddr(unsigned long addr)
 {
-	/*
-	 * bug_brk_handler() only called for BRK #BUG_BRK_IMM.
-	 * So the answer is trivial -- any spurious instances with no
-	 * bug table entry will be rejected by report_bug() and passed
-	 * back to the debug-monitors code and handled as a fatal
-	 * unexpected debug exception.
-	 */
-	return 1;
+	u32 insn;
+
+	if (aarch64_insn_read((u32 *)addr, &insn))
+		return 0;
+
+	/* Match ASM_BUG_FLAGS() / BUG() instructions. */
+	return insn == (0xd4200000 | (BUG_BRK_IMM << 5));
 }
 #endif
 

diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index b6ba4465f59d..8bbb082fd5e3 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c

@@ -26,6 +26,7 @@
 #include <linux/entry-common.h>
 #include <linux/kmsan.h>
 #include <linux/bug.h>
+#include <linux/uaccess.h>
 #include <asm/entry-percpu.h>
 #include <asm/asm-extable.h>
 #include <asm/irqflags.h>

@@ -55,7 +56,12 @@ static inline void __user *get_trap_ip(struct pt_regs *regs)
 #ifdef CONFIG_GENERIC_BUG
 int is_valid_bugaddr(unsigned long addr)
 {
-	return 1;
+	u16 insn;
+
+	if (get_kernel_nofault(insn, (u16 *)addr))
+		return 0;
+
+	return insn == 0x0001 || insn == 0x000e;
 }
 #endif