[PATCH AUTOSEL 5.4 25/37] powerpc/booke: Avoid link stack corruption in several places

From: Sasha Levin
Date: Thu Sep 09 2021 - 20:59:45 EST

From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>

[ Upstream commit f5007dbf4da729baa850b33a64dc3cc53757bdf8 ]

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

See commit c974809a26a1 ("powerpc/vdso: Avoid link stack corruption
in __get_datapage()") for details.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/e9fbc285eceb720e6c0e032ef47fe8b05f669b48.1629791751.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/powerpc/include/asm/ppc_asm.h | 2 +-
arch/powerpc/kernel/exceptions-64e.S | 6 +++---
arch/powerpc/kernel/fsl_booke_entry_mapping.S | 8 ++++----
arch/powerpc/kernel/head_44x.S | 6 +++---
arch/powerpc/kernel/head_fsl_booke.S | 6 +++---
arch/powerpc/mm/nohash/tlb_low.S | 4 ++--
6 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index 6b03dff61a05..8a0efc3fe1cd 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -306,7 +306,7 @@ GLUE(.,name):

/* Be careful, this will clobber the lr register. */
#define LOAD_REG_ADDR_PIC(reg, name) \
- bl 0f; \
+ bcl 20,31,$+4; \
0: mflr reg; \
addis reg,reg,(name - 0b)@ha; \
addi reg,reg,(name - 0b)@l;
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 829950b96d29..bb89efecf282 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -1245,7 +1245,7 @@ found_iprot:
* r3 = MAS0_TLBSEL (for the iprot array)
* r4 = SPRN_TLBnCFG
*/
- bl invstr /* Find our address */
+ bcl 20,31,$+4 /* Find our address */
invstr: mflr r6 /* Make it accessible */
mfmsr r7
rlwinm r5,r7,27,31,31 /* extract MSR[IS] */
@@ -1314,7 +1314,7 @@ skpinv: addi r6,r6,1 /* Increment */
mfmsr r6
xori r6,r6,MSR_IS
mtspr SPRN_SRR1,r6
- bl 1f /* Find our address */
+ bcl 20,31,$+4 /* Find our address */
1: mflr r6
addi r6,r6,(2f - 1b)
mtspr SPRN_SRR0,r6
@@ -1384,7 +1384,7 @@ skpinv: addi r6,r6,1 /* Increment */
* r4 = MAS0 w/TLBSEL & ESEL for the temp mapping
*/
/* Now we branch the new virtual address mapped by this entry */
- bl 1f /* Find our address */
+ bcl 20,31,$+4 /* Find our address */
1: mflr r6
addi r6,r6,(2f - 1b)
tovirt(r6,r6)
diff --git a/arch/powerpc/kernel/fsl_booke_entry_mapping.S b/arch/powerpc/kernel/fsl_booke_entry_mapping.S
index ea065282b303..26fab16cdb6e 100644
--- a/arch/powerpc/kernel/fsl_booke_entry_mapping.S
+++ b/arch/powerpc/kernel/fsl_booke_entry_mapping.S
@@ -1,7 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0 */

/* 1. Find the index of the entry we're executing in */
- bl invstr /* Find our address */
+ bcl 20,31,$+4 /* Find our address */
invstr: mflr r6 /* Make it accessible */
mfmsr r7
rlwinm r4,r7,27,31,31 /* extract MSR[IS] */
@@ -85,7 +85,7 @@ skpinv: addi r6,r6,1 /* Increment */
addi r6,r6,10
slw r6,r8,r6 /* convert to mask */

- bl 1f /* Find our address */
+ bcl 20,31,$+4 /* Find our address */
1: mflr r7

mfspr r8,SPRN_MAS3
@@ -117,7 +117,7 @@ skpinv: addi r6,r6,1 /* Increment */

xori r6,r4,1
slwi r6,r6,5 /* setup new context with other address space */
- bl 1f /* Find our address */
+ bcl 20,31,$+4 /* Find our address */
1: mflr r9
rlwimi r7,r9,0,20,31
addi r7,r7,(2f - 1b)
@@ -218,7 +218,7 @@ next_tlb_setup:

lis r7,MSR_KERNEL@h
ori r7,r7,MSR_KERNEL@l
- bl 1f /* Find our address */
+ bcl 20,31,$+4 /* Find our address */
1: mflr r9
rlwimi r6,r9,0,20,31
addi r6,r6,(2f - 1b)
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index 51dd01a27314..a9655536ffba 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -70,7 +70,7 @@ _ENTRY(_start);
* address.
* r21 will be loaded with the physical runtime address of _stext
*/
- bl 0f /* Get our runtime address */
+ bcl 20,31,$+4 /* Get our runtime address */
0: mflr r21 /* Make it accessible */
addis r21,r21,(_stext - 0b)@ha
addi r21,r21,(_stext - 0b)@l /* Get our current runtime base */
@@ -861,7 +861,7 @@ _GLOBAL(init_cpu_state)
wmmucr: mtspr SPRN_MMUCR,r3 /* Put MMUCR */
sync

- bl invstr /* Find our address */
+ bcl 20,31,$+4 /* Find our address */
invstr: mflr r5 /* Make it accessible */
tlbsx r23,0,r5 /* Find entry we are in */
li r4,0 /* Start at TLB entry 0 */
@@ -1053,7 +1053,7 @@ head_start_47x:
sync

/* Find the entry we are running from */
- bl 1f
+ bcl 20,31,$+4
1: mflr r23
tlbsx r23,0,r23
tlbre r24,r23,0
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index 519d49547e2f..f18174ee5084 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -79,7 +79,7 @@ _ENTRY(_start);
mr r23,r3
mr r25,r4

- bl 0f
+ bcl 20,31,$+4
0: mflr r8
addis r3,r8,(is_second_reloc - 0b)@ha
lwz r19,(is_second_reloc - 0b)@l(r3)
@@ -1139,7 +1139,7 @@ _GLOBAL(switch_to_as1)
bne 1b

/* Get the tlb entry used by the current running code */
- bl 0f
+ bcl 20,31,$+4
0: mflr r4
tlbsx 0,r4

@@ -1173,7 +1173,7 @@ _GLOBAL(switch_to_as1)
_GLOBAL(restore_to_as0)
mflr r0

- bl 0f
+ bcl 20,31,$+4
0: mflr r9
addi r9,r9,1f - 0b

diff --git a/arch/powerpc/mm/nohash/tlb_low.S b/arch/powerpc/mm/nohash/tlb_low.S
index eaeee402f96e..f849f26bfbfb 100644
--- a/arch/powerpc/mm/nohash/tlb_low.S
+++ b/arch/powerpc/mm/nohash/tlb_low.S
@@ -214,7 +214,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_476_DD2)
* Touch enough instruction cache lines to ensure cache hits
*/
1: mflr r9
- bl 2f
+ bcl 20,31,$+4
2: mflr r6
li r7,32
PPC_ICBT(0,R6,R7) /* touch next cache line */
@@ -442,7 +442,7 @@ _GLOBAL(loadcam_multi)
* Set up temporary TLB entry that is the same as what we're
* running from, but in AS=1.
*/
- bl 1f
+ bcl 20,31,$+4
1: mflr r6
tlbsx 0,r8
mfspr r6,SPRN_MAS1
--
2.30.2