From 7ab0b7cb8951d4095d73e203759b74d41916e455 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Fri, 16 Aug 2019 07:52:20 +0000 Subject: 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 Signed-off-by: Michael Ellerman Link: https://bugzilla.kernel.org/show_bug.cgi?id=204371 Link: https://lore.kernel.org/r/c6cea38f90480268d439ca44a645647e260fff09.1565941808.git.christophe.leroy@c-s.fr --- arch/powerpc/kernel/misc_32.S | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/powerpc/kernel/misc_32.S') 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 -- cgit v1.2.3-59-g8ed1b