Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 37318a3c authored by Grant Grundler's avatar Grant Grundler Committed by Kyle McMartin
Browse files

[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: default avatarGrant Grundler <grundler@parisc-linux.org>

Signed-off-by: default avatarKyle McMartin <kyle@parisc-linux.org>
parent c2709020

arch/parisc/kernel/pacache.S

+9 −4
Original line number Diff line number Diff line
@@ -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