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

[Mukesh Kumar Chaurasiya]

> 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
>  
Thanks for this.
lemme test these and i'll send it out after verifying.

Regards,
Mukesh