On 8/8/25 08:44, Sabyrzhan Tasbolatov wrote:

On Fri, Aug 8, 2025 at 10:07 AM Christophe Leroy
[off-list ref] wrote:

quoted

Le 07/08/2025 à 21:40, Sabyrzhan Tasbolatov a écrit :

quoted

Call kasan_init_generic() which handles Generic KASAN initialization.
For architectures that do not select ARCH_DEFER_KASAN,
this will be a no-op for the runtime flag but will
print the initialization banner.

For SW_TAGS and HW_TAGS modes, their respective init functions will
handle the flag enabling, if they are enabled/implemented.

Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217049
Signed-off-by: Sabyrzhan Tasbolatov <redacted>
Tested-by: Alexandre Ghiti <redacted> # riscv
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com> # s390
---
Changes in v5:
- Unified arch patches into a single one, where we just call
       kasan_init_generic()
- Added Tested-by tag for riscv (tested the same change in v4)
- Added Acked-by tag for s390 (tested the same change in v4)
---
   arch/arm/mm/kasan_init.c    | 2 +-
   arch/arm64/mm/kasan_init.c  | 4 +---
   arch/riscv/mm/kasan_init.c  | 1 +
   arch/s390/kernel/early.c    | 3 ++-
   arch/x86/mm/kasan_init_64.c | 2 +-
   arch/xtensa/mm/kasan_init.c | 2 +-
   6 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm/mm/kasan_init.c b/arch/arm/mm/kasan_init.c
index 111d4f70313..c6625e808bf 100644
--- a/arch/arm/mm/kasan_init.c
+++ b/arch/arm/mm/kasan_init.c

@@ -300,6 +300,6 @@ void __init kasan_init(void)
       local_flush_tlb_all();

       memset(kasan_early_shadow_page, 0, PAGE_SIZE);
-     pr_info("Kernel address sanitizer initialized\n");
       init_task.kasan_depth = 0;
+     kasan_init_generic();
   }

diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index d541ce45dae..abeb81bf6eb 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c

@@ -399,14 +399,12 @@ void __init kasan_init(void)
   {
       kasan_init_shadow();
       kasan_init_depth();
-#if defined(CONFIG_KASAN_GENERIC)
+     kasan_init_generic();
       /*
        * Generic KASAN is now fully initialized.
        * Software and Hardware Tag-Based modes still require
        * kasan_init_sw_tags() and kasan_init_hw_tags() correspondingly.
        */
-     pr_info("KernelAddressSanitizer initialized (generic)\n");
-#endif
   }

   #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */

diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index 41c635d6aca..ba2709b1eec 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c

@@ -530,6 +530,7 @@ void __init kasan_init(void)

       memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
       init_task.kasan_depth = 0;
+     kasan_init_generic();

I understood KASAN is really ready to function only once the csr_write()
and local_flush_tlb_all() below are done. Shouldn't kasan_init_generic()
be called after it ?

I will try to test this in v6:

         csr_write(CSR_SATP, PFN_DOWN(__pa(swapper_pg_dir)) | satp_mode);
         local_flush_tlb_all();
         kasan_init_generic();

Before setting the final kasan mapping, we still have the early one so 
we won't trap or anything on some kasan accesses. But if there is a v6, 
I agree it will be cleaner to do it this ^ way.

Thanks,

Alex

Alexandre Ghiti said [1] it was not a problem, but I will check.

[1] https://lore.kernel.org/all/20c1e656-512e-4424-9d4e-176af18bb7d6@ghiti.fr/ (local)

quoted

quoted

       csr_write(CSR_SATP, PFN_DOWN(__pa(swapper_pg_dir)) | satp_mode);
       local_flush_tlb_all();

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 9adfbdd377d..544e5403dd9 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c

@@ -21,6 +21,7 @@
   #include <linux/kernel.h>
   #include <asm/asm-extable.h>
   #include <linux/memblock.h>
+#include <linux/kasan.h>
   #include <asm/access-regs.h>
   #include <asm/asm-offsets.h>
   #include <asm/machine.h>

@@ -65,7 +66,7 @@ static void __init kasan_early_init(void)
   {
   #ifdef CONFIG_KASAN
       init_task.kasan_depth = 0;
-     pr_info("KernelAddressSanitizer initialized\n");
+     kasan_init_generic();
   #endif
   }

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 0539efd0d21..998b6010d6d 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c

@@ -451,5 +451,5 @@ void __init kasan_init(void)
       __flush_tlb_all();

       init_task.kasan_depth = 0;
-     pr_info("KernelAddressSanitizer initialized\n");
+     kasan_init_generic();
   }

diff --git a/arch/xtensa/mm/kasan_init.c b/arch/xtensa/mm/kasan_init.c
index f39c4d83173..0524b9ed5e6 100644
--- a/arch/xtensa/mm/kasan_init.c
+++ b/arch/xtensa/mm/kasan_init.c

@@ -94,5 +94,5 @@ void __init kasan_init(void)

       /* At this point kasan is fully initialized. Enable error messages. */
       current->kasan_depth = 0;
-     pr_info("KernelAddressSanitizer initialized\n");
+     kasan_init_generic();
   }

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