| Message ID | c6cea38f90480268d439ca44a645647e260fff09.1565941808.git.christophe.leroy@c-s.fr (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 7ab0b7cb8951d4095d73e203759b74d41916e455 |
| Headers | show |
| Series | powerpc/32: Add warning on misaligned copy_page() or clear_page() | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch next (c9633332103e55bc73d80d07ead28b95a22a85a3) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 28 lines checked |
On Fri, 2019-08-16 at 07:52:20 UTC, Christophe Leroy wrote: > 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> > Cc: Erhard F. <erhard_f@mailbox.org> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=204371 Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/7ab0b7cb8951d4095d73e203759b74d41916e455 cheers
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
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> Cc: Erhard F. <erhard_f@mailbox.org> Link: https://bugzilla.kernel.org/show_bug.cgi?id=204371 --- arch/powerpc/include/asm/page_32.h | 4 ++++ arch/powerpc/kernel/misc_32.S | 5 +++++ 2 files changed, 9 insertions(+)