diff options
| author | Christophe Leroy | 2019-08-16 07:52:20 +0000 |
|---|---|---|
| committer | Michael Ellerman | 2019-08-20 21:22:15 +1000 |
| commit | 7ab0b7cb8951d4095d73e203759b74d41916e455 (patch) | |
| tree | 4f63c162df91aa9231a46dcf1f4abc83b3cba0a5 | |
| parent | f204338f8e29777302042cba578b0da44f69695f (diff) | |
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
| -rw-r--r-- | arch/powerpc/include/asm/page_32.h | 4 | ||||
| -rw-r--r-- | arch/powerpc/kernel/misc_32.S | 5 |
2 files changed, 9 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/page_32.h b/arch/powerpc/include/asm/page_32.h index 683dfbc67ca8..d64dfe3ac712 100644 --- a/arch/powerpc/include/asm/page_32.h +++ b/arch/powerpc/include/asm/page_32.h @@ -40,6 +40,8 @@ typedef unsigned long long pte_basic_t; typedef unsigned long pte_basic_t; #endif +#include <asm/bug.h> + /* * Clear page using the dcbz instruction, which doesn't cause any * memory traffic (except to write out any cache lines which get @@ -49,6 +51,8 @@ static inline void clear_page(void *addr) { unsigned int i; + WARN_ON((unsigned long)addr & (L1_CACHE_BYTES - 1)); + for (i = 0; i < PAGE_SIZE / L1_CACHE_BYTES; i++, addr += L1_CACHE_BYTES) dcbz(addr); } 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 |