Commit adda7466 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390/purgatory: workaround llvm's IAS limitations 

llvm's integrated assembler cannot handle immediate values which are
calculated with two local labels:

arch/s390/purgatory/head.S:139:11: error: invalid operand for instruction
 aghi %r8,-(.base_crash-purgatory_start)

Workaround this by partially rewriting the code.

Link: https://lore.kernel.org/r/20220511120532.2228616-6-hca@linux.ibm.com


Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 4c25f0ff

arch/s390/purgatory/head.S

+23 −7
Original line number Diff line number Diff line
@@ -44,11 +44,14 @@ 
.endm



.macro MEMSWAP dst,src,buf,len

10:	cghi	\len,bufsz

10:	larl	%r0,purgatory_end

	larl	%r1,stack

	slgr	%r0,%r1

	cgr	\len,%r0

	jh	11f

	lgr	%r4,\len

	j	12f

11:	lghi	%r4,bufsz

11:	lgr	%r4,%r0



12:	MEMCPY	\buf,\dst,%r4

	MEMCPY	\dst,\src,%r4
@@ -135,12 +138,18 @@ ENTRY(purgatory_start) 


.start_crash_kernel:

	/* Location of purgatory_start in crash memory */

	larl	%r0,.base_crash

	larl	%r1,purgatory_start

	slgr	%r0,%r1

	lgr	%r8,%r13

	aghi	%r8,-(.base_crash-purgatory_start)

	sgr	%r8,%r0



	/* Destination for this code i.e. end of memory to be swapped. */

	larl	%r0,purgatory_end

	larl	%r1,purgatory_start

	slgr	%r0,%r1

	lg	%r9,crash_size-.base_crash(%r13)

	aghi	%r9,-(purgatory_end-purgatory_start)

	sgr	%r9,%r0



	/* Destination in crash memory, i.e. same as r9 but in crash memory. */

	lg	%r10,crash_start-.base_crash(%r13)
@@ -149,15 +158,19 @@ ENTRY(purgatory_start) 
	/* Buffer location (in crash memory) and size. As the purgatory is

	 * behind the point of no return it can re-use the stack as buffer.

	 */

	lghi	%r11,bufsz

	larl	%r11,purgatory_end

	larl	%r12,stack

	slgr	%r11,%r12



	MEMCPY	%r12,%r9,%r11	/* dst	-> (crash) buf */

	MEMCPY	%r9,%r8,%r11	/* self -> dst */



	/* Jump to new location. */

	lgr	%r7,%r9

	aghi	%r7,.jump_to_dst-purgatory_start

	larl	%r0,.jump_to_dst

	larl	%r1,purgatory_start

	slgr	%r0,%r1

	agr	%r7,%r0

	br	%r7



.jump_to_dst:
@@ -169,7 +182,10 @@ ENTRY(purgatory_start) 


	/* Load new buffer location after jump */

	larl	%r7,stack

	aghi	%r10,stack-purgatory_start

	lgr	%r0,%r7

	larl	%r1,purgatory_start

	slgr	%r0,%r1

	agr	%r10,%r0

	MEMCPY	%r10,%r7,%r11	/* (new) buf -> (crash) buf */



	/* Now the code is set up to run from its designated location. Start