Re: [PATCH v5 09/15] arch/powerpc: don't initialize kasan if it's disabled

On 12/03/26 16:53, Christophe Leroy (CS GROUP) wrote:

Le 12/03/2026 à 12:12, Sourabh Jain a écrit :

quoted

On 25/02/26 13:44, Baoquan He wrote:

quoted

Here, kasan is disabled if specified 'kasan=off' in kernel cmdline.

This includes 32bit, book3s/64 and book3e/64.

Signed-off-by: Baoquan He <redacted>
Cc: linuxppc-dev@lists.ozlabs.org
---
  arch/powerpc/mm/kasan/init_32.c        | 6 +++++-
  arch/powerpc/mm/kasan/init_book3e_64.c | 4 ++++
  arch/powerpc/mm/kasan/init_book3s_64.c | 4 ++++
  3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/kasan/init_32.c b/arch/powerpc/mm/kasan/ init_32.c
index 1d083597464f..0ea2a636c992 100644
--- a/arch/powerpc/mm/kasan/init_32.c
+++ b/arch/powerpc/mm/kasan/init_32.c

@@ -141,6 +141,10 @@ void __init kasan_init(void)

      u64 i;
      int ret;
+    /* If KASAN is disabled via command line, don't initialize it. */
+    if (kasan_arg_disabled)
+        return;
+
      for_each_mem_range(i, &base, &end) {
          phys_addr_t top = min(end, total_lowmem);

@@ -170,7 +174,7 @@ void __init kasan_init(void)

  void __init kasan_late_init(void)
  {
-    if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
+    if (IS_ENABLED(CONFIG_KASAN_VMALLOC) && kasan_enabled())
          kasan_unmap_early_shadow_vmalloc();
  }

diff --git a/arch/powerpc/mm/kasan/init_book3e_64.c b/arch/powerpc/mm/ kasan/init_book3e_64.c
index 0d3a73d6d4b0..fbe4c9a7e460 100644
--- a/arch/powerpc/mm/kasan/init_book3e_64.c
+++ b/arch/powerpc/mm/kasan/init_book3e_64.c

@@ -111,6 +111,10 @@ void __init kasan_init(void)

      u64 i;
      pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL_RO);
+    /* If KASAN is disabled via command line, don't initialize it. */
+    if (kasan_arg_disabled)
+        return;
+
      for_each_mem_range(i, &start, &end)
          kasan_init_phys_region(phys_to_virt(start), phys_to_virt(end));

diff --git a/arch/powerpc/mm/kasan/init_book3s_64.c b/arch/powerpc/mm/ kasan/init_book3s_64.c
index dcafa641804c..f7906f9ef9be 100644
--- a/arch/powerpc/mm/kasan/init_book3s_64.c
+++ b/arch/powerpc/mm/kasan/init_book3s_64.c

@@ -54,6 +54,10 @@ void __init kasan_init(void)

      u64 i;
      pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL);
+    /* If KASAN is disabled via command line, don't initialize it. */
+    if (kasan_arg_disabled)
+        return;
+
      if (!early_radix_enabled()) {
          pr_warn("KASAN not enabled as it requires radix!");
          return;

Should we log in the kernel log buffer that KASAN is disabled?

Right now, I don't see the kernel advertising the same.

When KASAN is enabled it is advertised with:

    pr_info("KernelAddressSanitizer initialized (generic)\n");

Isn't the absence of that message enough to understand KASAN is not there ?

Yes this should work. Thanks.


- Sourabh Jain

quoted

$ dmesg | grep -i kasan
[    0.000000] Kernel command line: BOOT_IMAGE=(ieee1275//vdevice/v- scsi@30000070/disk@8100000000000000,msdos2)/vmlinuz-7.0.0-rc3+ crashkernel=2G kasan=off

Tested this series on powerpc Pseries platform.
So feel free to add:
Tested-by: Sourabh Jain <redacted>

- Sourabh Jain