[Intel-xe] ✗ CI.checkpatch: warning for x86/alternatives: Disable KASAN in apply_alternatives()

[Patchwork]

== Series Details ==

Series: x86/alternatives: Disable KASAN in apply_alternatives()
URL   : https://patchwork.freedesktop.org/series/125179/
State : warning

== Summary ==

+ KERNEL=/kernel
+ git clone https://gitlab.freedesktop.org/drm/maintainer-tools mt
Cloning into 'mt'...
warning: redirecting to https://gitlab.freedesktop.org/drm/maintainer-tools.git/
+ git -C mt rev-list -n1 origin/master
63c2b6b160bca2df6efc7bc4cea6f442097d7854
+ cd /kernel
+ git config --global --add safe.directory /kernel
+ git log -n1
commit 8d7d96593caaf61021dbb6e26f7dae57dfb74962
Author: Kirill A. Shutemov <kirill.shutemov at linux.intel.com>
Date:   Mon Oct 16 08:40:24 2023 -0700

    x86/alternatives: Disable KASAN in apply_alternatives()
    
    Fei has reported that KASAN triggers during apply_alternatives() on
    a 5-level paging machine:
    
            BUG: KASAN: out-of-bounds in rcu_is_watching()
            Read of size 4 at addr ff110003ee6419a0 by task swapper/0/0
            ...
            __asan_load4()
            rcu_is_watching()
            trace_hardirqs_on()
            text_poke_early()
            apply_alternatives()
            ...
    
    On machines with 5-level paging, cpu_feature_enabled(X86_FEATURE_LA57)
    gets patched. It includes KASAN code, where KASAN_SHADOW_START depends on
    __VIRTUAL_MASK_SHIFT, which is defined with cpu_feature_enabled().
    
    KASAN gets confused when apply_alternatives() patches the
    KASAN_SHADOW_START users. A test patch that makes KASAN_SHADOW_START
    static, by replacing __VIRTUAL_MASK_SHIFT with 56, works around the issue.
    
    Fix it for real by disabling KASAN while the kernel is patching alternatives.
    
    [ mingo: updated the changelog ]
    
    Fixes: 6657fca06e3f ("x86/mm: Allow to boot without LA57 if CONFIG_X86_5LEVEL=y")
    Reported-by: Fei Yang <fei.yang at intel.com>
    Signed-off-by: Kirill A. Shutemov <kirill.shutemov at linux.intel.com>
    Signed-off-by: Ingo Molnar <mingo at kernel.org>
    Acked-by: Peter Zijlstra (Intel) <peterz at infradead.org>
    Cc: Linus Torvalds <torvalds at linux-foundation.org>
    Cc: stable at vger.kernel.org
    Link: https://lore.kernel.org/r/20231012100424.1456-1-kirill.shutemov@linux.intel.com
    (cherry picked from commit d35652a5fc9944784f6f50a5c979518ff8dacf61)
+ /mt/dim checkpatch ab7cd1b4af95baba2d6ce5487d35ffda523e895d drm-intel
8d7d96593 x86/alternatives: Disable KASAN in apply_alternatives()
-:27: WARNING:COMMIT_LOG_LONG_LINE: Prefer a maximum 75 chars per line (possible unwrapped commit description?)
#27: 
Fix it for real by disabling KASAN while the kernel is patching alternatives.

-:31: WARNING:UNKNOWN_COMMIT_ID: Unknown commit id '6657fca06e3f', maybe rebased or not pulled?
#31: 
Fixes: 6657fca06e3f ("x86/mm: Allow to boot without LA57 if CONFIG_X86_5LEVEL=y")

-:32: WARNING:BAD_REPORTED_BY_LINK: Reported-by: should be immediately followed by Closes: with a URL to the report
#32: 
Reported-by: Fei Yang <fei.yang at intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov at linux.intel.com>

total: 0 errors, 3 warnings, 0 checks, 25 lines checked