linux-kernel - Re: [PATCH 5/9] kasan/loongarch: call kasan_init_generic in kasan

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Message-ID: <20250626132943.GJ1613200@noisy.programming.kicks-ass.net>
Date: Thu, 26 Jun 2025 15:29:43 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Sabyrzhan Tasbolatov <snovitoll@...il.com>
Cc: ryabinin.a.a@...il.com, glider@...gle.com, andreyknvl@...il.com,
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Subject: Re: [PATCH 5/9] kasan/loongarch: call kasan_init_generic in
 kasan_init

On Wed, Jun 25, 2025 at 02:52:20PM +0500, Sabyrzhan Tasbolatov wrote:
> Call kasan_init_generic() which enables the static flag
> to mark generic KASAN initialized, otherwise it's an inline stub.
> 
> Replace `kasan_arch_is_ready` with `kasan_enabled`.
> Delete the flag `kasan_early_stage` in favor of the global static key
> enabled via kasan_enabled().
> 
> printk banner is printed earlier right where `kasan_early_stage`
> was flipped, just to keep the same flow.
> 
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218315
> Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@...il.com>
> ---
>  arch/loongarch/include/asm/kasan.h | 7 -------
>  arch/loongarch/mm/kasan_init.c     | 7 ++-----
>  2 files changed, 2 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/loongarch/include/asm/kasan.h b/arch/loongarch/include/asm/kasan.h
> index 7f52bd31b9d..b0b74871257 100644
> --- a/arch/loongarch/include/asm/kasan.h
> +++ b/arch/loongarch/include/asm/kasan.h
> @@ -66,7 +66,6 @@
>  #define XKPRANGE_WC_SHADOW_OFFSET	(KASAN_SHADOW_START + XKPRANGE_WC_KASAN_OFFSET)
>  #define XKVRANGE_VC_SHADOW_OFFSET	(KASAN_SHADOW_START + XKVRANGE_VC_KASAN_OFFSET)
>  
> -extern bool kasan_early_stage;
>  extern unsigned char kasan_early_shadow_page[PAGE_SIZE];
>  
>  #define kasan_mem_to_shadow kasan_mem_to_shadow
> @@ -75,12 +74,6 @@ void *kasan_mem_to_shadow(const void *addr);
>  #define kasan_shadow_to_mem kasan_shadow_to_mem
>  const void *kasan_shadow_to_mem(const void *shadow_addr);
>  
> -#define kasan_arch_is_ready kasan_arch_is_ready
> -static __always_inline bool kasan_arch_is_ready(void)
> -{
> -	return !kasan_early_stage;
> -}
> -
>  #define addr_has_metadata addr_has_metadata
>  static __always_inline bool addr_has_metadata(const void *addr)
>  {
> diff --git a/arch/loongarch/mm/kasan_init.c b/arch/loongarch/mm/kasan_init.c
> index d2681272d8f..cf8315f9119 100644
> --- a/arch/loongarch/mm/kasan_init.c
> +++ b/arch/loongarch/mm/kasan_init.c
> @@ -40,11 +40,9 @@ static pgd_t kasan_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
>  #define __pte_none(early, pte) (early ? pte_none(pte) : \
>  ((pte_val(pte) & _PFN_MASK) == (unsigned long)__pa(kasan_early_shadow_page)))
>  
> -bool kasan_early_stage = true;
> -
>  void *kasan_mem_to_shadow(const void *addr)
>  {
> -	if (!kasan_arch_is_ready()) {
> +	if (!kasan_enabled()) {
>  		return (void *)(kasan_early_shadow_page);
>  	} else {
>  		unsigned long maddr = (unsigned long)addr;
> @@ -298,7 +296,7 @@ void __init kasan_init(void)
>  	kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
>  					kasan_mem_to_shadow((void *)KFENCE_AREA_END));
>  
> -	kasan_early_stage = false;
> +	kasan_init_generic();
>  
>  	/* Populate the linear mapping */
>  	for_each_mem_range(i, &pa_start, &pa_end) {
> @@ -329,5 +327,4 @@ void __init kasan_init(void)
>  
>  	/* At this point kasan is fully initialized. Enable error messages */
>  	init_task.kasan_depth = 0;
> -	pr_info("KernelAddressSanitizer initialized.\n");
>  }

This one is weird because its the only arch that does things after
marking early_state false.

Is that really correct, or should kasan_init_generic() be last, like all
the other architectures?

Also, please move init_task.kasan_depth = 0 into the generic thing.
ARM64 might have fooled you with the wrapper function, but they all do
this right before that pr_info you're taking out.