* [PATCH] powerpc/booke: Avoid link stack corruption in several places
@ 2021-08-23 7:53 Christophe Leroy
2021-08-23 15:58 ` Segher Boessenkool
0 siblings, 1 reply; 4+ messages in thread
From: Christophe Leroy @ 2021-08-23 7:53 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman
Cc: linux-kernel, linuxppc-dev
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@csgroup.eu>
---
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 ffe712307e11..2a675ba927ab 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -260,7 +260,7 @@ GLUE(.,name):
/* Be careful, this will clobber the lr register. */
#define LOAD_REG_ADDR_PIC(reg, name) \
- bl 0f; \
+ bcl 20,31,0f \
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 1401787b0b93..0a1835a0ec12 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -1127,7 +1127,7 @@ found_iprot:
* r3 = MAS0_TLBSEL (for the iprot array)
* r4 = SPRN_TLBnCFG
*/
- bl invstr /* Find our address */
+ bcl 20,31,invstr /* Find our address */
invstr: mflr r6 /* Make it accessible */
mfmsr r7
rlwinm r5,r7,27,31,31 /* extract MSR[IS] */
@@ -1196,7 +1196,7 @@ skpinv: addi r6,r6,1 /* Increment */
mfmsr r6
xori r6,r6,MSR_IS
mtspr SPRN_SRR1,r6
- bl 1f /* Find our address */
+ bcl 20,31,1f /* Find our address */
1: mflr r6
addi r6,r6,(2f - 1b)
mtspr SPRN_SRR0,r6
@@ -1256,7 +1256,7 @@ 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 20,31,1f /* 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 8bccce6544b5..a9e2235f6c40 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,invstr /* 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 20,31,1f /* 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 20,31,1f /* Find our address */
1: mflr r9
rlwimi r7,r9,0,20,31
addi r7,r7,(2f - 1b)
@@ -207,7 +207,7 @@ next_tlb_setup:
lis r7,MSR_KERNEL@h
ori r7,r7,MSR_KERNEL@l
- bl 1f /* Find our address */
+ bcl 20,31,1f /* 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 ddc978a2d381..b14efa87d1cf 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 20,31,0f /* 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 */
@@ -853,7 +853,7 @@ _GLOBAL(init_cpu_state)
wmmucr: mtspr SPRN_MMUCR,r3 /* Put MMUCR */
sync
- bl invstr /* Find our address */
+ bcl 20,31,invstr /* 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 */
@@ -1045,7 +1045,7 @@ head_start_47x:
sync
/* Find the entry we are running from */
- bl 1f
+ bcl 20,31,1f
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 0f9642f36b49..dd197da2ffcc 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 20,31,0f
0: mflr r8
addis r3,r8,(is_second_reloc - 0b)@ha
lwz r19,(is_second_reloc - 0b)@l(r3)
@@ -1132,7 +1132,7 @@ _GLOBAL(switch_to_as1)
bne 1b
/* Get the tlb entry used by the current running code */
- bl 0f
+ bcl 20,31,0f
0: mflr r4
tlbsx 0,r4
@@ -1166,7 +1166,7 @@ _GLOBAL(switch_to_as1)
_GLOBAL(restore_to_as0)
mflr r0
- bl 0f
+ bcl 20,31,0f
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 4613bf8e9aae..8b225a3df7e3 100644
--- a/arch/powerpc/mm/nohash/tlb_low.S
+++ b/arch/powerpc/mm/nohash/tlb_low.S
@@ -199,7 +199,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_476_DD2)
* Touch enough instruction cache lines to ensure cache hits
*/
1: mflr r9
- bl 2f
+ bcl 20,31,2f
2: mflr r6
li r7,32
PPC_ICBT(0,R6,R7) /* touch next cache line */
@@ -414,7 +414,7 @@ _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 20,31,1f
1: mflr r6
tlbsx 0,r8
mfspr r6,SPRN_MAS1
--
2.25.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/booke: Avoid link stack corruption in several places
2021-08-23 7:53 [PATCH] powerpc/booke: Avoid link stack corruption in several places Christophe Leroy
@ 2021-08-23 15:58 ` Segher Boessenkool
2021-08-23 17:05 ` Christophe Leroy
0 siblings, 1 reply; 4+ messages in thread
From: Segher Boessenkool @ 2021-08-23 15:58 UTC (permalink / raw)
To: Christophe Leroy
Cc: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
linuxppc-dev, linux-kernel
On Mon, Aug 23, 2021 at 07:53:01AM +0000, Christophe Leroy wrote:
> /* Be careful, this will clobber the lr register. */
> #define LOAD_REG_ADDR_PIC(reg, name) \
> - bl 0f; \
> + bcl 20,31,0f \
> 0: mflr reg; \
> addis reg,reg,(name - 0b)@ha; \
> addi reg,reg,(name - 0b)@l;
The code ended each line with a semicolon before, for absolutely no
reason that I can see, but still. Fixing that would be nice, but only
doing it on one line isn't good.
Btw. Both the 7450 and the modern cores implementing this really need
this to be $+4, so it is a lot clearer to write that instead of 1f or
a named label.
Segher
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/booke: Avoid link stack corruption in several places
2021-08-23 15:58 ` Segher Boessenkool
@ 2021-08-23 17:05 ` Christophe Leroy
2021-08-23 20:12 ` Segher Boessenkool
0 siblings, 1 reply; 4+ messages in thread
From: Christophe Leroy @ 2021-08-23 17:05 UTC (permalink / raw)
To: Segher Boessenkool
Cc: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
linuxppc-dev, linux-kernel
Le 23/08/2021 à 17:58, Segher Boessenkool a écrit :
> On Mon, Aug 23, 2021 at 07:53:01AM +0000, Christophe Leroy wrote:
>> /* Be careful, this will clobber the lr register. */
>> #define LOAD_REG_ADDR_PIC(reg, name) \
>> - bl 0f; \
>> + bcl 20,31,0f \
>> 0: mflr reg; \
>> addis reg,reg,(name - 0b)@ha; \
>> addi reg,reg,(name - 0b)@l;
>
> The code ended each line with a semicolon before, for absolutely no
> reason that I can see, but still. Fixing that would be nice, but only
> doing it on one line isn't good.
Sure, forgetting the semicolon broke the build. That's because the backslash removes the newline.
The cleanest way I found to fix that quite of stuff is by using GAS macro, as I did for
LOAD_REG_IMMEDIATE() some time ago.
>
> Btw. Both the 7450 and the modern cores implementing this really need
> this to be $+4, so it is a lot clearer to write that instead of 1f or
> a named label.
I like that, removing unneeded labels will make it smoother and clearer. I'll do it.
Christophe
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/booke: Avoid link stack corruption in several places
2021-08-23 17:05 ` Christophe Leroy
@ 2021-08-23 20:12 ` Segher Boessenkool
0 siblings, 0 replies; 4+ messages in thread
From: Segher Boessenkool @ 2021-08-23 20:12 UTC (permalink / raw)
To: Christophe Leroy
Cc: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
linuxppc-dev, linux-kernel
On Mon, Aug 23, 2021 at 07:05:38PM +0200, Christophe Leroy wrote:
> Le 23/08/2021 à 17:58, Segher Boessenkool a écrit :
> >On Mon, Aug 23, 2021 at 07:53:01AM +0000, Christophe Leroy wrote:
> >> /* Be careful, this will clobber the lr register. */
> >> #define LOAD_REG_ADDR_PIC(reg, name) \
> >>- bl 0f; \
> >>+ bcl 20,31,0f \
> >> 0: mflr reg; \
> >> addis reg,reg,(name - 0b)@ha; \
> >> addi reg,reg,(name - 0b)@l;
> >
> >The code ended each line with a semicolon before, for absolutely no
> >reason that I can see, but still. Fixing that would be nice, but only
> >doing it on one line isn't good.
>
> Sure, forgetting the semicolon broke the build. That's because the
> backslash removes the newline.
Ah right, one of the surprises you get from using the C preprocessor on
non-C code :-)
> The cleanest way I found to fix that quite of stuff is by using GAS macro,
> as I did for LOAD_REG_IMMEDIATE() some time ago.
Yeah, good plan. You can use loops and saner parameters etc. as well if
you do :-)
> >Btw. Both the 7450 and the modern cores implementing this really need
> >this to be $+4, so it is a lot clearer to write that instead of 1f or
> >a named label.
>
> I like that, removing unneeded labels will make it smoother and clearer.
> I'll do it.
Cool, thanks!
Segher
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-08-23 7:53 [PATCH] powerpc/booke: Avoid link stack corruption in several places Christophe Leroy
2021-08-23 15:58 ` Segher Boessenkool
2021-08-23 17:05 ` Christophe Leroy
2021-08-23 20:12 ` Segher Boessenkool
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