From 37318a3cb1028933417533084ddbf9d84be06878 Mon Sep 17 00:00:00 2001 From: Grant Grundler Date: Fri, 21 Oct 2005 22:55:34 -0400 Subject: [PATCH] [PARISC] Fix copy_user_page_asm to NOT access past end of page 2.6.12-rc2-pa3 fix copy_user_page_asm to NOT access past end of page. My bad. /o\ Lamont confirmed that instructions following a conditional branch are *alway* executed regardless if the branch is taken or not. Unless they are nullified (which was missing in this case). He also noted: Conditional branches nullify on forward taken branch, and on non-taken backward branch. Note that .+4 is a backwards branch. This makes alot more sense than the giberish in the PA20 arch book. Compiles and boots on both 64-bit (a500) and 32-bit (j6k). Signed-off-by: Grant Grundler Signed-off-by: Kyle McMartin --- arch/parisc/kernel/pacache.S | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/arch/parisc/kernel/pacache.S b/arch/parisc/kernel/pacache.S index 4a7d9c8903f4..e217ae369fbb 100644 --- a/arch/parisc/kernel/pacache.S +++ b/arch/parisc/kernel/pacache.S @@ -351,7 +351,11 @@ copy_user_page_asm: std %r22, 120(%r26) ldo 128(%r26), %r26 - ADDIB> -1, %r1, 1b /* bundle 10 */ + /* conditional branches nullify on forward taken branch, and on + * non-taken backward branch. Note that .+4 is a backwards branch. + * The ldd should only get executed if the branch is taken. + */ + ADDIB>,n -1, %r1, 1b /* bundle 10 */ ldd 0(%r25), %r19 /* start next loads */ #else @@ -363,10 +367,10 @@ copy_user_page_asm: * the full 64 bit register values on interrupt, we can't * use ldd/std on a 32 bit kernel. */ + ldw 0(%r25), %r19 ldi 64, %r1 /* PAGE_SIZE/64 == 64 */ 1: - ldw 0(%r25), %r19 ldw 4(%r25), %r20 ldw 8(%r25), %r21 ldw 12(%r25), %r22 @@ -396,11 +400,12 @@ copy_user_page_asm: ldw 60(%r25), %r22 stw %r19, 48(%r26) stw %r20, 52(%r26) + ldo 64(%r25), %r25 stw %r21, 56(%r26) stw %r22, 60(%r26) ldo 64(%r26), %r26 - ADDIB> -1, %r1, 1b - ldo 64(%r25), %r25 + ADDIB>,n -1, %r1, 1b + ldw 0(%r25), %r19 #endif bv %r0(%r2) nop -- 2.39.5