* [PATCH kernel v3] powerpc/boot: Stop using RELACOUNT
@ 2022-04-06 7:00 ` Alexey Kardashevskiy
0 siblings, 0 replies; 4+ messages in thread
From: Alexey Kardashevskiy @ 2022-04-06 7:00 UTC (permalink / raw)
To: llvm
Cc: Alexey Kardashevskiy, linuxppc-dev, Gabriel Paubert,
Nick Desaulniers, Nathan Chancellor, Michael Ellerman
So far the RELACOUNT tag from the ELF header was containing the exact
number of R_PPC_RELATIVE/R_PPC64_RELATIVE relocations. However the LLVM's
recent change [1] make it equal-or-less than the actual number which
makes it useless.
This replaces RELACOUNT in zImage loader with a pair of RELASZ and RELAENT.
The vmlinux relocation code is fixed in commit d79976918852
("powerpc/64: Add UADDR64 relocation support").
To make it more future proof, this walks through the entire .rela.dyn
section instead of assuming that the section is sorter by a relocation
type. Unlike d79976918852, this does not add unaligned UADDR/UADDR64
relocations as we are likely not to see those in practice - the zImage
is small and very arch specific so there is a smaller chance that some
generic feature (such as PRINK_INDEX) triggers unaligned relocations.
[1] https://github.com/llvm/llvm-project/commit/da0e5b885b25cf4
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v3:
* s/divd/divdu/ for ppc64
v2:
* s/divd/divwu/ for ppc32
* updated the commit log
* named all new labels instead of numbering them
(s/101f/.Lcheck_for_relaent/ and so on)
---
arch/powerpc/boot/crt0.S | 45 ++++++++++++++++++++++++++--------------
1 file changed, 29 insertions(+), 16 deletions(-)
diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S
index feadee18e271..44544720daae 100644
--- a/arch/powerpc/boot/crt0.S
+++ b/arch/powerpc/boot/crt0.S
@@ -8,7 +8,8 @@
#include "ppc_asm.h"
RELA = 7
-RELACOUNT = 0x6ffffff9
+RELASZ = 8
+RELAENT = 9
.data
/* A procedure descriptor used when booting this as a COFF file.
@@ -75,34 +76,39 @@ p_base: mflr r10 /* r10 now points to runtime addr of p_base */
bne 11f
lwz r9,4(r12) /* get RELA pointer in r9 */
b 12f
-11: addis r8,r8,(-RELACOUNT)@ha
- cmpwi r8,RELACOUNT@l
+11: cmpwi r8,RELASZ
+ bne .Lcheck_for_relaent
+ lwz r0,4(r12) /* get RELASZ value in r0 */
+ b 12f
+.Lcheck_for_relaent:
+ cmpwi r8,RELAENT
bne 12f
- lwz r0,4(r12) /* get RELACOUNT value in r0 */
+ lwz r14,4(r12) /* get RELAENT value in r14 */
12: addi r12,r12,8
b 9b
/* The relocation section contains a list of relocations.
* We now do the R_PPC_RELATIVE ones, which point to words
- * which need to be initialized with addend + offset.
- * The R_PPC_RELATIVE ones come first and there are RELACOUNT
- * of them. */
+ * which need to be initialized with addend + offset */
10: /* skip relocation if we don't have both */
cmpwi r0,0
beq 3f
cmpwi r9,0
beq 3f
+ cmpwi r14,0
+ beq 3f
add r9,r9,r11 /* Relocate RELA pointer */
+ divwu r0,r0,r14 /* RELASZ / RELAENT */
mtctr r0
2: lbz r0,4+3(r9) /* ELF32_R_INFO(reloc->r_info) */
cmpwi r0,22 /* R_PPC_RELATIVE */
- bne 3f
+ bne .Lnext
lwz r12,0(r9) /* reloc->r_offset */
lwz r0,8(r9) /* reloc->r_addend */
add r0,r0,r11
stwx r0,r11,r12
- addi r9,r9,12
+.Lnext: add r9,r9,r14
bdnz 2b
/* Do a cache flush for our text, in case the loader didn't */
@@ -160,32 +166,39 @@ p_base: mflr r10 /* r10 now points to runtime addr of p_base */
bne 10f
ld r13,8(r11) /* get RELA pointer in r13 */
b 11f
-10: addis r12,r12,(-RELACOUNT)@ha
- cmpdi r12,RELACOUNT@l
- bne 11f
- ld r8,8(r11) /* get RELACOUNT value in r8 */
+10: cmpwi r12,RELASZ
+ bne .Lcheck_for_relaent
+ lwz r8,8(r11) /* get RELASZ pointer in r8 */
+ b 11f
+.Lcheck_for_relaent:
+ cmpwi r12,RELAENT
+ bne 11f
+ lwz r14,8(r11) /* get RELAENT pointer in r14 */
11: addi r11,r11,16
b 9b
12:
- cmpdi r13,0 /* check we have both RELA and RELACOUNT */
+ cmpdi r13,0 /* check we have both RELA, RELASZ, RELAENT*/
cmpdi cr1,r8,0
beq 3f
beq cr1,3f
+ cmpdi r14,0
+ beq 3f
/* Calcuate the runtime offset. */
subf r13,r13,r9
/* Run through the list of relocations and process the
* R_PPC64_RELATIVE ones. */
+ divdu r8,r8,r14 /* RELASZ / RELAENT */
mtctr r8
13: ld r0,8(r9) /* ELF64_R_TYPE(reloc->r_info) */
cmpdi r0,22 /* R_PPC64_RELATIVE */
- bne 3f
+ bne .Lnext
ld r12,0(r9) /* reloc->r_offset */
ld r0,16(r9) /* reloc->r_addend */
add r0,r0,r13
stdx r0,r13,r12
- addi r9,r9,24
+.Lnext: add r9,r9,r14
bdnz 13b
/* Do a cache flush for our text, in case the loader didn't */
--
2.30.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH kernel v3] powerpc/boot: Stop using RELACOUNT
@ 2022-04-06 7:00 ` Alexey Kardashevskiy
0 siblings, 0 replies; 4+ messages in thread
From: Alexey Kardashevskiy @ 2022-04-06 7:00 UTC (permalink / raw)
To: llvm
Cc: Alexey Kardashevskiy, Nick Desaulniers, Nathan Chancellor, linuxppc-dev
So far the RELACOUNT tag from the ELF header was containing the exact
number of R_PPC_RELATIVE/R_PPC64_RELATIVE relocations. However the LLVM's
recent change [1] make it equal-or-less than the actual number which
makes it useless.
This replaces RELACOUNT in zImage loader with a pair of RELASZ and RELAENT.
The vmlinux relocation code is fixed in commit d79976918852
("powerpc/64: Add UADDR64 relocation support").
To make it more future proof, this walks through the entire .rela.dyn
section instead of assuming that the section is sorter by a relocation
type. Unlike d79976918852, this does not add unaligned UADDR/UADDR64
relocations as we are likely not to see those in practice - the zImage
is small and very arch specific so there is a smaller chance that some
generic feature (such as PRINK_INDEX) triggers unaligned relocations.
[1] https://github.com/llvm/llvm-project/commit/da0e5b885b25cf4
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v3:
* s/divd/divdu/ for ppc64
v2:
* s/divd/divwu/ for ppc32
* updated the commit log
* named all new labels instead of numbering them
(s/101f/.Lcheck_for_relaent/ and so on)
---
arch/powerpc/boot/crt0.S | 45 ++++++++++++++++++++++++++--------------
1 file changed, 29 insertions(+), 16 deletions(-)
diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S
index feadee18e271..44544720daae 100644
--- a/arch/powerpc/boot/crt0.S
+++ b/arch/powerpc/boot/crt0.S
@@ -8,7 +8,8 @@
#include "ppc_asm.h"
RELA = 7
-RELACOUNT = 0x6ffffff9
+RELASZ = 8
+RELAENT = 9
.data
/* A procedure descriptor used when booting this as a COFF file.
@@ -75,34 +76,39 @@ p_base: mflr r10 /* r10 now points to runtime addr of p_base */
bne 11f
lwz r9,4(r12) /* get RELA pointer in r9 */
b 12f
-11: addis r8,r8,(-RELACOUNT)@ha
- cmpwi r8,RELACOUNT@l
+11: cmpwi r8,RELASZ
+ bne .Lcheck_for_relaent
+ lwz r0,4(r12) /* get RELASZ value in r0 */
+ b 12f
+.Lcheck_for_relaent:
+ cmpwi r8,RELAENT
bne 12f
- lwz r0,4(r12) /* get RELACOUNT value in r0 */
+ lwz r14,4(r12) /* get RELAENT value in r14 */
12: addi r12,r12,8
b 9b
/* The relocation section contains a list of relocations.
* We now do the R_PPC_RELATIVE ones, which point to words
- * which need to be initialized with addend + offset.
- * The R_PPC_RELATIVE ones come first and there are RELACOUNT
- * of them. */
+ * which need to be initialized with addend + offset */
10: /* skip relocation if we don't have both */
cmpwi r0,0
beq 3f
cmpwi r9,0
beq 3f
+ cmpwi r14,0
+ beq 3f
add r9,r9,r11 /* Relocate RELA pointer */
+ divwu r0,r0,r14 /* RELASZ / RELAENT */
mtctr r0
2: lbz r0,4+3(r9) /* ELF32_R_INFO(reloc->r_info) */
cmpwi r0,22 /* R_PPC_RELATIVE */
- bne 3f
+ bne .Lnext
lwz r12,0(r9) /* reloc->r_offset */
lwz r0,8(r9) /* reloc->r_addend */
add r0,r0,r11
stwx r0,r11,r12
- addi r9,r9,12
+.Lnext: add r9,r9,r14
bdnz 2b
/* Do a cache flush for our text, in case the loader didn't */
@@ -160,32 +166,39 @@ p_base: mflr r10 /* r10 now points to runtime addr of p_base */
bne 10f
ld r13,8(r11) /* get RELA pointer in r13 */
b 11f
-10: addis r12,r12,(-RELACOUNT)@ha
- cmpdi r12,RELACOUNT@l
- bne 11f
- ld r8,8(r11) /* get RELACOUNT value in r8 */
+10: cmpwi r12,RELASZ
+ bne .Lcheck_for_relaent
+ lwz r8,8(r11) /* get RELASZ pointer in r8 */
+ b 11f
+.Lcheck_for_relaent:
+ cmpwi r12,RELAENT
+ bne 11f
+ lwz r14,8(r11) /* get RELAENT pointer in r14 */
11: addi r11,r11,16
b 9b
12:
- cmpdi r13,0 /* check we have both RELA and RELACOUNT */
+ cmpdi r13,0 /* check we have both RELA, RELASZ, RELAENT*/
cmpdi cr1,r8,0
beq 3f
beq cr1,3f
+ cmpdi r14,0
+ beq 3f
/* Calcuate the runtime offset. */
subf r13,r13,r9
/* Run through the list of relocations and process the
* R_PPC64_RELATIVE ones. */
+ divdu r8,r8,r14 /* RELASZ / RELAENT */
mtctr r8
13: ld r0,8(r9) /* ELF64_R_TYPE(reloc->r_info) */
cmpdi r0,22 /* R_PPC64_RELATIVE */
- bne 3f
+ bne .Lnext
ld r12,0(r9) /* reloc->r_offset */
ld r0,16(r9) /* reloc->r_addend */
add r0,r0,r13
stdx r0,r13,r12
- addi r9,r9,24
+.Lnext: add r9,r9,r14
bdnz 13b
/* Do a cache flush for our text, in case the loader didn't */
--
2.30.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH kernel v3] powerpc/boot: Stop using RELACOUNT
2022-04-06 7:00 ` Alexey Kardashevskiy
@ 2022-05-15 10:28 ` Michael Ellerman
-1 siblings, 0 replies; 4+ messages in thread
From: Michael Ellerman @ 2022-05-15 10:28 UTC (permalink / raw)
To: Alexey Kardashevskiy, llvm
Cc: Nathan Chancellor, linuxppc-dev, Nick Desaulniers
On Wed, 6 Apr 2022 17:00:38 +1000, Alexey Kardashevskiy wrote:
> So far the RELACOUNT tag from the ELF header was containing the exact
> number of R_PPC_RELATIVE/R_PPC64_RELATIVE relocations. However the LLVM's
> recent change [1] make it equal-or-less than the actual number which
> makes it useless.
>
> This replaces RELACOUNT in zImage loader with a pair of RELASZ and RELAENT.
> The vmlinux relocation code is fixed in commit d79976918852
> ("powerpc/64: Add UADDR64 relocation support").
>
> [...]
Applied to powerpc/next.
[1/1] powerpc/boot: Stop using RELACOUNT
https://git.kernel.org/powerpc/c/c14d31bae372e050b053f2511fb3f0f90c27e4f9
cheers
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH kernel v3] powerpc/boot: Stop using RELACOUNT
@ 2022-05-15 10:28 ` Michael Ellerman
0 siblings, 0 replies; 4+ messages in thread
From: Michael Ellerman @ 2022-05-15 10:28 UTC (permalink / raw)
To: Alexey Kardashevskiy, llvm
Cc: Gabriel Paubert, Nick Desaulniers, linuxppc-dev,
Michael Ellerman, Nathan Chancellor
On Wed, 6 Apr 2022 17:00:38 +1000, Alexey Kardashevskiy wrote:
> So far the RELACOUNT tag from the ELF header was containing the exact
> number of R_PPC_RELATIVE/R_PPC64_RELATIVE relocations. However the LLVM's
> recent change [1] make it equal-or-less than the actual number which
> makes it useless.
>
> This replaces RELACOUNT in zImage loader with a pair of RELASZ and RELAENT.
> The vmlinux relocation code is fixed in commit d79976918852
> ("powerpc/64: Add UADDR64 relocation support").
>
> [...]
Applied to powerpc/next.
[1/1] powerpc/boot: Stop using RELACOUNT
https://git.kernel.org/powerpc/c/c14d31bae372e050b053f2511fb3f0f90c27e4f9
cheers
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-05-15 10:31 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-04-06 7:00 [PATCH kernel v3] powerpc/boot: Stop using RELACOUNT Alexey Kardashevskiy
2022-04-06 7:00 ` Alexey Kardashevskiy
2022-05-15 10:28 ` Michael Ellerman
2022-05-15 10:28 ` Michael Ellerman
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