From: Mark Nelson Subject: [PATCH] powerpc: Fix 64bit memcpy() regression Date: Thu, 26 Feb 2009 10:26:48 +1100 Message-ID: <200902261026.48183.markn@au1.ibm.com> References: <49A2705D.9030008@in.ibm.com> <49A395ED.5030607@in.ibm.com> <200902251752.56514.markn@au1.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: linuxppc-dev@ozlabs.org, "Sachin P. Sant" , Geert Uytterhoeven , Jan Kara , Jan Kara , Mel Gorman , linux-kernel , Paul Mackerras , Andrew Morton , linux-ext4@vger.kernel.org To: benh@kernel.crashing.org Return-path: Received: from e23smtp02.au.ibm.com ([202.81.31.144]:43657 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756566AbZBYXZT (ORCPT ); Wed, 25 Feb 2009 18:25:19 -0500 In-Reply-To: <200902251752.56514.markn@au1.ibm.com> Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: This fixes a regression introduced by commit 25d6e2d7c58ddc4a3b614fc5381591c0cfe66556 ("powerpc: Update 64bit memcpy() using CPU_FTR_UNALIGNED_LD_STD"). This commit allowed CPUs that have the CPU_FTR_UNALIGNED_LD_STD CPU feature bit present to do the memcpy() with unaligned load doubles. But, along with this came a bug where our final load double would read bytes beyond a page boundary and into the next (unmapped) page. This was caught by enabling CONFIG_DEBUG_PAGEALLOC, The fix was to read only the number of bytes that we need to store rather than reading a full 8-byte doubleword and storing only a portion of that. In order to minimise the amount of existing code touched we use the original do_tail for the src_unaligned case. Below is an example of the regression, as reported by Sachin Sant: Unable to handle kernel paging request for data at address 0xc00000003f380000 Faulting instruction address: 0xc000000000039574 cpu 0x1: Vector: 300 (Data Access) at [c00000003baf3020] pc: c000000000039574: .memcpy+0x74/0x244 lr: d00000000244916c: .ext3_xattr_get+0x288/0x2f4 [ext3] sp: c00000003baf32a0 msr: 8000000000009032 dar: c00000003f380000 dsisr: 40000000 current = 0xc00000003e54b010 paca = 0xc000000000a53680 pid = 1840, comm = readahead enter ? for help [link register ] d00000000244916c .ext3_xattr_get+0x288/0x2f4 [ext3] [c00000003baf32a0] d000000002449104 .ext3_xattr_get+0x220/0x2f4 [ext3] (unreliab le) [c00000003baf3390] d00000000244a6e8 .ext3_xattr_security_get+0x40/0x5c [ext3] [c00000003baf3400] c000000000148154 .generic_getxattr+0x74/0x9c [c00000003baf34a0] c000000000333400 .inode_doinit_with_dentry+0x1c4/0x678 [c00000003baf3560] c00000000032c6b0 .security_d_instantiate+0x50/0x68 [c00000003baf35e0] c00000000013c818 .d_instantiate+0x78/0x9c [c00000003baf3680] c00000000013ced0 .d_splice_alias+0xf0/0x120 [c00000003baf3720] d00000000243e05c .ext3_lookup+0xec/0x134 [ext3] [c00000003baf37c0] c000000000131e74 .do_lookup+0x110/0x260 [c00000003baf3880] c000000000134ed0 .__link_path_walk+0xa98/0x1010 [c00000003baf3970] c0000000001354a0 .path_walk+0x58/0xc4 [c00000003baf3a20] c000000000135720 .do_path_lookup+0x138/0x1e4 [c00000003baf3ad0] c00000000013645c .path_lookup_open+0x6c/0xc8 [c00000003baf3b70] c000000000136780 .do_filp_open+0xcc/0x874 [c00000003baf3d10] c0000000001251e0 .do_sys_open+0x80/0x140 [c00000003baf3dc0] c00000000016aaec .compat_sys_open+0x24/0x38 [c00000003baf3e30] c00000000000855c syscall_exit+0x0/0x40 --- Exception: c01 (System Call) at 000000000ff0ef18 SP (ffc6f4b0) is in userspace 1:mon> Signed-off-by: Mark Nelson Reported-by: Sachin Sant Tested-by: Sachin Sant --- arch/powerpc/lib/memcpy_64.S | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) Index: upstream/arch/powerpc/lib/memcpy_64.S =================================================================== --- upstream.orig/arch/powerpc/lib/memcpy_64.S +++ upstream/arch/powerpc/lib/memcpy_64.S @@ -53,18 +53,19 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_ 3: std r8,8(r3) beq 3f addi r3,r3,16 - ld r9,8(r4) .Ldo_tail: bf cr7*4+1,1f - rotldi r9,r9,32 + lwz r9,8(r4) + addi r4,r4,4 stw r9,0(r3) addi r3,r3,4 1: bf cr7*4+2,2f - rotldi r9,r9,16 + lhz r9,8(r4) + addi r4,r4,2 sth r9,0(r3) addi r3,r3,2 2: bf cr7*4+3,3f - rotldi r9,r9,8 + lbz r9,8(r4) stb r9,0(r3) 3: ld r3,48(r1) /* return dest pointer */ blr @@ -133,11 +134,24 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_ cmpwi cr1,r5,8 addi r3,r3,32 sld r9,r9,r10 - ble cr1,.Ldo_tail + ble cr1,6f ld r0,8(r4) srd r7,r0,r11 or r9,r7,r9 - b .Ldo_tail +6: + bf cr7*4+1,1f + rotldi r9,r9,32 + stw r9,0(r3) + addi r3,r3,4 +1: bf cr7*4+2,2f + rotldi r9,r9,16 + sth r9,0(r3) + addi r3,r3,2 +2: bf cr7*4+3,3f + rotldi r9,r9,8 + stb r9,0(r3) +3: ld r3,48(r1) /* return dest pointer */ + blr .Ldst_unaligned: PPC_MTOCRF 0x01,r6 # put #bytes to 8B bdry into cr7