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Commit aa0eecb0 authored Nov 17, 2005 by Carlos O'Donell Committed by Kyle McMartin Nov 17, 2005

[PARISC] Document some register usages in assembly files



Document clobbers and args in entry.S and syscall.S.

entry.S: Add comment to indicate that cr27 may recycle and EDEADLOCK
detection is not 100% correct. Since this is only enabled when using
ENABLE_LWS_DEBUG, the user is warned by the comment.

Signed-off-by: Carlos O'Donell <carlos@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>

parent 75be99a8

arch/parisc/kernel/entry.S

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -1846,6 +1846,7 @@ sys_clone_wrapper:
	ldo -16(%r30),%r29 /* Reference param save area */		ldo -16(%r30),%r29 /* Reference param save area */
	#endif		#endif

			/* WARNING - Clobbers r19 and r21, userspace must save these! */
	STREG %r2,PT_GR19(%r1) /* save for child */		STREG %r2,PT_GR19(%r1) /* save for child */
	STREG %r30,PT_GR21(%r1)		STREG %r30,PT_GR21(%r1)
	BL sys_clone,%r2		BL sys_clone,%r2

arch/parisc/kernel/syscall.S

+2 −1

Original line number	Original line	Diff line number	Diff line
	@@ -164,7 +164,7 @@ linux_gateway_entry:
	#endif		#endif
	STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */		STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */

	STREG %r20, TASK_PT_GR20(%r1)		STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */
	STREG %r21, TASK_PT_GR21(%r1)		STREG %r21, TASK_PT_GR21(%r1)
	STREG %r22, TASK_PT_GR22(%r1)		STREG %r22, TASK_PT_GR22(%r1)
	STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */		STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */
	@@ -527,6 +527,7 @@ lws_compare_and_swap:
	We must giveup this call and fail.		We must giveup this call and fail.
	*/		*/
	ldw 4(%sr2,%r20), %r28 /* Load thread register */		ldw 4(%sr2,%r20), %r28 /* Load thread register */
			/* WARNING: If cr27 cycles to the same value we have problems */
	mfctl %cr27, %r21 /* Get current thread register */		mfctl %cr27, %r21 /* Get current thread register */
	cmpb,<>,n %r21, %r28, cas_lock /* Called recursive? */		cmpb,<>,n %r21, %r28, cas_lock /* Called recursive? */
	b lws_exit /* Return error! */		b lws_exit /* Return error! */