Commit 33e14024 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc: Avoid link stack corruption in misc asm functions 



bl;mflr is used at several places to get code position.

Use bcl 20,31,+4 instead of bl in order to preserve link stack.

See commit c974809a ("powerpc/vdso: Avoid link stack corruption
in __get_datapage()") for details.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c6eabb4fb6c156f75d56dcbcc6f243e5ac0fba42.1629791763.git.christophe.leroy@csgroup.eu
parent f5007dbf

arch/powerpc/kernel/misc.S

+1 −1
Original line number Diff line number Diff line
@@ -29,7 +29,7 @@ _GLOBAL(reloc_offset) 
	li	r3, 0

_GLOBAL(add_reloc_offset)

	mflr	r0

	bl	1f

	bcl	20,31,$+4

1:	mflr	r5

	PPC_LL	r4,(2f-1b)(r5)

	subf	r5,r4,r5

arch/powerpc/kernel/misc_32.S

+1 −1
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ _GLOBAL(reloc_got2) 
	srwi.	r8,r8,2

	beqlr

	mtctr	r8

	bl	1f

	bcl	20,31,$+4

1:	mflr	r0

	lis	r4,1b@ha

	addi	r4,r4,1b@l

arch/powerpc/kernel/misc_64.S

+1 −1
Original line number Diff line number Diff line
@@ -255,7 +255,7 @@ _GLOBAL(scom970_write) 
 * Physical (hardware) cpu id should be in r3.

 */

_GLOBAL(kexec_wait)

	bl	1f

	bcl	20,31,$+4

1:	mflr	r5

	addi	r5,r5,kexec_flag-1b

arch/powerpc/kernel/reloc_32.S

+1 −1
Original line number Diff line number Diff line
@@ -30,7 +30,7 @@ R_PPC_RELATIVE = 22 
_GLOBAL(relocate)



	mflr	r0		/* Save our LR */

	bl	0f		/* Find our current runtime address */

	bcl	20,31,$+4	/* Find our current runtime address */

0:	mflr	r12		/* Make it accessible */

	mtlr	r0

arch/powerpc/kexec/relocate_32.S

+6 −6
Original line number Diff line number Diff line
@@ -93,7 +93,7 @@ wmmucr: 
	 * Invalidate all the TLB entries except the current entry

	 * where we are running from

	 */

	bl	0f				/* Find our address */

	bcl	20,31,$+4			/* Find our address */

0:	mflr	r5				/* Make it accessible */

	tlbsx	r23,0,r5			/* Find entry we are in */

	li	r4,0				/* Start at TLB entry 0 */
@@ -158,7 +158,7 @@ write_out: 
	/* Switch to other address space in MSR */

	insrwi	r9, r7, 1, 26		/* Set MSR[IS] = r7 */



	bl	1f

	bcl	20,31,$+4

1:	mflr	r8

	addi	r8, r8, (2f-1b)		/* Find the target offset */
@@ -202,7 +202,7 @@ next_tlb: 
	li	r9,0

	insrwi	r9, r7, 1, 26			/* Set MSR[IS] = r7 */



	bl	1f

	bcl	20,31,$+4

1:	mflr	r8

	and	r8, r8, r11			/* Get our offset within page */

	addi	r8, r8, (2f-1b)
@@ -240,7 +240,7 @@ setup_map_47x: 
	sync



	/* Find the entry we are running from */

	bl	2f

	bcl	20,31,$+4

2:	mflr	r23

	tlbsx	r23, 0, r23

	tlbre	r24, r23, 0			/* TLB Word 0 */
@@ -296,7 +296,7 @@ clear_utlb_entry: 
	/* Update the msr to the new TS */

	insrwi	r5, r7, 1, 26



	bl	1f

	bcl	20,31,$+4

1:	mflr	r6

	addi	r6, r6, (2f-1b)
@@ -355,7 +355,7 @@ write_utlb: 
	/* Defaults to 256M */

	lis	r10, 0x1000



	bl	1f

	bcl	20,31,$+4

1:	mflr	r4

	addi	r4, r4, (2f-1b)			/* virtual address  of 2f */