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| author | Grant Grundler <grundler@parisc-linux.org> | 2005-10-21 22:55:34 -0400 |
|---|---|---|
| committer | Kyle McMartin <kyle@parisc-linux.org> | 2005-10-21 22:55:34 -0400 |
| commit | 37318a3cb1028933417533084ddbf9d84be06878 (patch) | |
| tree | 2806c46b71e68f2c5da2cff54adfc0407a5b7cce /arch | |
| parent | c2709020adb442f7d25f0805af08a3b6cfedd7be (diff) | |
| download | linux-37318a3cb1028933417533084ddbf9d84be06878.tar.gz linux-37318a3cb1028933417533084ddbf9d84be06878.tar.bz2 linux-37318a3cb1028933417533084ddbf9d84be06878.zip | |
[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 <grundler@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/parisc/kernel/pacache.S | 13 |
1 files 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 |