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| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2019-08-16 10:52:20 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-08-20 14:22:15 +0300 |
| commit | 7ab0b7cb8951d4095d73e203759b74d41916e455 (patch) | |
| tree | 4f63c162df91aa9231a46dcf1f4abc83b3cba0a5 /arch/powerpc/kernel/misc_32.S | |
| parent | f204338f8e29777302042cba578b0da44f69695f (diff) | |
| download | linux-7ab0b7cb8951d4095d73e203759b74d41916e455.tar.xz | |
powerpc/32: Add warning on misaligned copy_page() or clear_page()
copy_page() and clear_page() expect page aligned destination, and
use dcbz instruction to clear entire cache lines based on the
assumption that the destination is cache aligned.
As shown during analysis of a bug in BTRFS filesystem, a misaligned
copy_page() can create bugs that are difficult to locate (see Link).
Add an explicit WARNING when copy_page() or clear_page() are called
with misaligned destination.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=204371
Link: https://lore.kernel.org/r/c6cea38f90480268d439ca44a645647e260fff09.1565941808.git.christophe.leroy@c-s.fr
Diffstat (limited to 'arch/powerpc/kernel/misc_32.S')
| -rw-r--r-- | arch/powerpc/kernel/misc_32.S | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S index fe4bd321730e..02d90e1ebf65 100644 --- a/arch/powerpc/kernel/misc_32.S +++ b/arch/powerpc/kernel/misc_32.S @@ -452,7 +452,12 @@ END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE) stwu r9,16(r3) _GLOBAL(copy_page) + rlwinm r5, r3, 0, L1_CACHE_BYTES - 1 addi r3,r3,-4 + +0: twnei r5, 0 /* WARN if r3 is not cache aligned */ + EMIT_BUG_ENTRY 0b,__FILE__,__LINE__, BUGFLAG_WARNING + addi r4,r4,-4 li r5,4 |