Instead of using absolute addresses for both the old instrucions and
the alternative instructions, use offsets relative to the alt_entry
values. So we can not only cut the size of the alternative entry, but
also meet the prerequisite for patching alternatives in the vDSO,
since absolute alternative entries are subject to dynamic relocation,
which is incompatible with the vDSO building.
Signed-off-by: Jisheng Zhang <[email protected]>
---
arch/riscv/errata/sifive/errata.c | 4 +++-
arch/riscv/errata/thead/errata.c | 11 ++++++++---
arch/riscv/include/asm/alternative-macros.h | 20 ++++++++++----------
arch/riscv/include/asm/alternative.h | 12 ++++++------
arch/riscv/kernel/cpufeature.c | 13 ++++++-------
5 files changed, 33 insertions(+), 27 deletions(-)
diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
index 1031038423e7..0e537cdfd324 100644
--- a/arch/riscv/errata/sifive/errata.c
+++ b/arch/riscv/errata/sifive/errata.c
@@ -107,7 +107,9 @@ void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
tmp = (1U << alt->errata_id);
if (cpu_req_errata & tmp) {
- patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
+ patch_text_nosync((void *)&alt->old_offset + alt->old_offset,
+ (void *)&alt->alt_offset + alt->alt_offset,
+ alt->alt_len);
cpu_apply_errata |= tmp;
}
}
diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
index 21546937db39..2a6e335b5a32 100644
--- a/arch/riscv/errata/thead/errata.c
+++ b/arch/riscv/errata/thead/errata.c
@@ -68,6 +68,7 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
struct alt_entry *alt;
u32 cpu_req_errata = thead_errata_probe(stage, archid, impid);
u32 tmp;
+ void *oldptr, *updptr;
for (alt = begin; alt < end; alt++) {
if (alt->vendor_id != THEAD_VENDOR_ID)
@@ -77,12 +78,16 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
tmp = (1U << alt->errata_id);
if (cpu_req_errata & tmp) {
+ oldptr = (void *)&alt->old_offset + alt->old_offset;
+ updptr = (void *)&alt->alt_offset + alt->alt_offset;
+
/* On vm-alternatives, the mmu isn't running yet */
if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
- memcpy((void *)__pa_symbol(alt->old_ptr),
- (void *)__pa_symbol(alt->alt_ptr), alt->alt_len);
+ memcpy((void *)__pa_symbol(oldptr),
+ (void *)__pa_symbol(updptr),
+ alt->alt_len);
else
- patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
+ patch_text_nosync(oldptr, updptr, alt->alt_len);
}
}
diff --git a/arch/riscv/include/asm/alternative-macros.h b/arch/riscv/include/asm/alternative-macros.h
index ec2f3f1b836f..dd40727bc859 100644
--- a/arch/riscv/include/asm/alternative-macros.h
+++ b/arch/riscv/include/asm/alternative-macros.h
@@ -7,11 +7,11 @@
#ifdef __ASSEMBLY__
.macro ALT_ENTRY oldptr newptr vendor_id errata_id new_len
- RISCV_PTR \oldptr
- RISCV_PTR \newptr
- REG_ASM \vendor_id
- REG_ASM \new_len
- .word \errata_id
+ .long \oldptr - .
+ .long \newptr - .
+ .short \vendor_id
+ .short \new_len
+ .long \errata_id
.endm
.macro ALT_NEW_CONTENT vendor_id, errata_id, enable = 1, new_c : vararg
@@ -75,11 +75,11 @@
#include <linux/stringify.h>
#define ALT_ENTRY(oldptr, newptr, vendor_id, errata_id, newlen) \
- RISCV_PTR " " oldptr "\n" \
- RISCV_PTR " " newptr "\n" \
- REG_ASM " " vendor_id "\n" \
- REG_ASM " " newlen "\n" \
- ".word " errata_id "\n"
+ ".long ((" oldptr ") - .) \n" \
+ ".long ((" newptr ") - .) \n" \
+ ".short " vendor_id "\n" \
+ ".short " newlen "\n" \
+ ".long " errata_id "\n"
#define ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c) \
".if " __stringify(enable) " == 1\n" \
diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h
index 33eae9541684..3baf32e05b46 100644
--- a/arch/riscv/include/asm/alternative.h
+++ b/arch/riscv/include/asm/alternative.h
@@ -33,12 +33,12 @@ void riscv_alternative_fix_jal(void *alt_ptr, unsigned int len,
int patch_offset);
struct alt_entry {
- void *old_ptr; /* address of original instruciton or data */
- void *alt_ptr; /* address of replacement instruction or data */
- unsigned long vendor_id; /* cpu vendor id */
- unsigned long alt_len; /* The replacement size */
- unsigned int errata_id; /* The errata id */
-} __packed;
+ s32 old_offset; /* offset to original instruciton or data */
+ s32 alt_offset; /* offset to replacement instruction or data */
+ u16 vendor_id; /* cpu vendor id */
+ u16 alt_len; /* The replacement size */
+ u32 errata_id; /* The errata id */
+};
struct errata_checkfunc_id {
unsigned long vendor_id;
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 6244be5cd94a..adeac90b1d8e 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -257,6 +257,7 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
unsigned int stage)
{
struct alt_entry *alt;
+ void *oldptr, *updptr;
if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
return;
@@ -270,17 +271,15 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
continue;
}
+ oldptr = (void *)&alt->old_offset + alt->old_offset;
+ updptr = (void *)&alt->alt_offset + alt->alt_offset;
if (!__riscv_isa_extension_available(NULL, alt->errata_id))
continue;
/* do the basic patching */
- patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
- riscv_alternative_fix_auipc_jalr(alt->old_ptr,
- alt->alt_len,
- alt->old_ptr - alt->alt_ptr);
- riscv_alternative_fix_jal(alt->old_ptr,
- alt->alt_len,
- alt->old_ptr - alt->alt_ptr);
+ patch_text_nosync(oldptr, updptr, alt->alt_len);
+ riscv_alternative_fix_auipc_jalr(oldptr, alt->alt_len, oldptr - updptr);
+ riscv_alternative_fix_jal(oldptr, alt->alt_len, oldptr - updptr);
}
}
#endif
--
2.37.2
On Mon, Dec 5, 2022 at 1:57 AM Jisheng Zhang <[email protected]> wrote:
>
> Instead of using absolute addresses for both the old instrucions and
> the alternative instructions, use offsets relative to the alt_entry
> values. So we can not only cut the size of the alternative entry, but
> also meet the prerequisite for patching alternatives in the vDSO,
> since absolute alternative entries are subject to dynamic relocation,
> which is incompatible with the vDSO building.
>
> Signed-off-by: Jisheng Zhang <[email protected]>
> ---
> arch/riscv/errata/sifive/errata.c | 4 +++-
> arch/riscv/errata/thead/errata.c | 11 ++++++++---
> arch/riscv/include/asm/alternative-macros.h | 20 ++++++++++----------
> arch/riscv/include/asm/alternative.h | 12 ++++++------
> arch/riscv/kernel/cpufeature.c | 13 ++++++-------
> 5 files changed, 33 insertions(+), 27 deletions(-)
>
> diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
> index 1031038423e7..0e537cdfd324 100644
> --- a/arch/riscv/errata/sifive/errata.c
> +++ b/arch/riscv/errata/sifive/errata.c
> @@ -107,7 +107,9 @@ void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
>
> tmp = (1U << alt->errata_id);
> if (cpu_req_errata & tmp) {
> - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> + patch_text_nosync((void *)&alt->old_offset + alt->old_offset,
> + (void *)&alt->alt_offset + alt->alt_offset,
(void *)&alt->alt_offset + alt->alt_offset. ??!!
> + alt->alt_len);
> cpu_apply_errata |= tmp;
> }
> }
> diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
> index 21546937db39..2a6e335b5a32 100644
> --- a/arch/riscv/errata/thead/errata.c
> +++ b/arch/riscv/errata/thead/errata.c
> @@ -68,6 +68,7 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
> struct alt_entry *alt;
> u32 cpu_req_errata = thead_errata_probe(stage, archid, impid);
> u32 tmp;
> + void *oldptr, *updptr;
>
> for (alt = begin; alt < end; alt++) {
> if (alt->vendor_id != THEAD_VENDOR_ID)
> @@ -77,12 +78,16 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
>
> tmp = (1U << alt->errata_id);
> if (cpu_req_errata & tmp) {
> + oldptr = (void *)&alt->old_offset + alt->old_offset;
> + updptr = (void *)&alt->alt_offset + alt->alt_offset;
> +
> /* On vm-alternatives, the mmu isn't running yet */
> if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
> - memcpy((void *)__pa_symbol(alt->old_ptr),
> - (void *)__pa_symbol(alt->alt_ptr), alt->alt_len);
> + memcpy((void *)__pa_symbol(oldptr),
> + (void *)__pa_symbol(updptr),
> + alt->alt_len);
> else
> - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> + patch_text_nosync(oldptr, updptr, alt->alt_len);
> }
> }
>
> diff --git a/arch/riscv/include/asm/alternative-macros.h b/arch/riscv/include/asm/alternative-macros.h
> index ec2f3f1b836f..dd40727bc859 100644
> --- a/arch/riscv/include/asm/alternative-macros.h
> +++ b/arch/riscv/include/asm/alternative-macros.h
> @@ -7,11 +7,11 @@
> #ifdef __ASSEMBLY__
>
> .macro ALT_ENTRY oldptr newptr vendor_id errata_id new_len
> - RISCV_PTR \oldptr
> - RISCV_PTR \newptr
> - REG_ASM \vendor_id
> - REG_ASM \new_len
> - .word \errata_id
> + .long \oldptr - .
> + .long \newptr - .
> + .short \vendor_id
> + .short \new_len
> + .long \errata_id
> .endm
>
> .macro ALT_NEW_CONTENT vendor_id, errata_id, enable = 1, new_c : vararg
> @@ -75,11 +75,11 @@
> #include <linux/stringify.h>
>
> #define ALT_ENTRY(oldptr, newptr, vendor_id, errata_id, newlen) \
> - RISCV_PTR " " oldptr "\n" \
> - RISCV_PTR " " newptr "\n" \
> - REG_ASM " " vendor_id "\n" \
> - REG_ASM " " newlen "\n" \
> - ".word " errata_id "\n"
> + ".long ((" oldptr ") - .) \n" \
> + ".long ((" newptr ") - .) \n" \
> + ".short " vendor_id "\n" \
> + ".short " newlen "\n" \
> + ".long " errata_id "\n"
>
> #define ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c) \
> ".if " __stringify(enable) " == 1\n" \
> diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h
> index 33eae9541684..3baf32e05b46 100644
> --- a/arch/riscv/include/asm/alternative.h
> +++ b/arch/riscv/include/asm/alternative.h
> @@ -33,12 +33,12 @@ void riscv_alternative_fix_jal(void *alt_ptr, unsigned int len,
> int patch_offset);
>
> struct alt_entry {
> - void *old_ptr; /* address of original instruciton or data */
> - void *alt_ptr; /* address of replacement instruction or data */
> - unsigned long vendor_id; /* cpu vendor id */
> - unsigned long alt_len; /* The replacement size */
> - unsigned int errata_id; /* The errata id */
> -} __packed;
> + s32 old_offset; /* offset to original instruciton or data */
> + s32 alt_offset; /* offset to replacement instruction or data */
> + u16 vendor_id; /* cpu vendor id */
> + u16 alt_len; /* The replacement size */
> + u32 errata_id; /* The errata id */
> +};
>
> struct errata_checkfunc_id {
> unsigned long vendor_id;
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 6244be5cd94a..adeac90b1d8e 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -257,6 +257,7 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
> unsigned int stage)
> {
> struct alt_entry *alt;
> + void *oldptr, *updptr;
>
> if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
> return;
> @@ -270,17 +271,15 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
> continue;
> }
>
> + oldptr = (void *)&alt->old_offset + alt->old_offset;
> + updptr = (void *)&alt->alt_offset + alt->alt_offset;
> if (!__riscv_isa_extension_available(NULL, alt->errata_id))
> continue;
>
> /* do the basic patching */
> - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> - riscv_alternative_fix_auipc_jalr(alt->old_ptr,
> - alt->alt_len,
> - alt->old_ptr - alt->alt_ptr);
> - riscv_alternative_fix_jal(alt->old_ptr,
> - alt->alt_len,
> - alt->old_ptr - alt->alt_ptr);
> + patch_text_nosync(oldptr, updptr, alt->alt_len);
> + riscv_alternative_fix_auipc_jalr(oldptr, alt->alt_len, oldptr - updptr);
> + riscv_alternative_fix_jal(oldptr, alt->alt_len, oldptr - updptr);
> }
> }
> #endif
> --
> 2.37.2
>
--
Best Regards
Guo Ren
On Mon, Dec 05, 2022 at 08:51:41AM +0800, Guo Ren wrote:
> On Mon, Dec 5, 2022 at 1:57 AM Jisheng Zhang <[email protected]> wrote:
> >
> > Instead of using absolute addresses for both the old instrucions and
> > the alternative instructions, use offsets relative to the alt_entry
> > values. So we can not only cut the size of the alternative entry, but
> > also meet the prerequisite for patching alternatives in the vDSO,
> > since absolute alternative entries are subject to dynamic relocation,
> > which is incompatible with the vDSO building.
> >
> > Signed-off-by: Jisheng Zhang <[email protected]>
> > ---
> > arch/riscv/errata/sifive/errata.c | 4 +++-
> > arch/riscv/errata/thead/errata.c | 11 ++++++++---
> > arch/riscv/include/asm/alternative-macros.h | 20 ++++++++++----------
> > arch/riscv/include/asm/alternative.h | 12 ++++++------
> > arch/riscv/kernel/cpufeature.c | 13 ++++++-------
> > 5 files changed, 33 insertions(+), 27 deletions(-)
> >
> > diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
> > index 1031038423e7..0e537cdfd324 100644
> > --- a/arch/riscv/errata/sifive/errata.c
> > +++ b/arch/riscv/errata/sifive/errata.c
> > @@ -107,7 +107,9 @@ void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
> >
> > tmp = (1U << alt->errata_id);
> > if (cpu_req_errata & tmp) {
> > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> > + patch_text_nosync((void *)&alt->old_offset + alt->old_offset,
> > + (void *)&alt->alt_offset + alt->alt_offset,
> (void *)&alt->alt_offset + alt->alt_offset. ??!!
Hi Guo,
what's the problem? I can't catch your meaning, could you please proide
more details?
Thanks
>
> > + alt->alt_len);
> > cpu_apply_errata |= tmp;
> > }
> > }
> > diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
> > index 21546937db39..2a6e335b5a32 100644
> > --- a/arch/riscv/errata/thead/errata.c
> > +++ b/arch/riscv/errata/thead/errata.c
> > @@ -68,6 +68,7 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
> > struct alt_entry *alt;
> > u32 cpu_req_errata = thead_errata_probe(stage, archid, impid);
> > u32 tmp;
> > + void *oldptr, *updptr;
> >
> > for (alt = begin; alt < end; alt++) {
> > if (alt->vendor_id != THEAD_VENDOR_ID)
> > @@ -77,12 +78,16 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
> >
> > tmp = (1U << alt->errata_id);
> > if (cpu_req_errata & tmp) {
> > + oldptr = (void *)&alt->old_offset + alt->old_offset;
> > + updptr = (void *)&alt->alt_offset + alt->alt_offset;
> > +
> > /* On vm-alternatives, the mmu isn't running yet */
> > if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
> > - memcpy((void *)__pa_symbol(alt->old_ptr),
> > - (void *)__pa_symbol(alt->alt_ptr), alt->alt_len);
> > + memcpy((void *)__pa_symbol(oldptr),
> > + (void *)__pa_symbol(updptr),
> > + alt->alt_len);
> > else
> > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> > + patch_text_nosync(oldptr, updptr, alt->alt_len);
> > }
> > }
> >
> > diff --git a/arch/riscv/include/asm/alternative-macros.h b/arch/riscv/include/asm/alternative-macros.h
> > index ec2f3f1b836f..dd40727bc859 100644
> > --- a/arch/riscv/include/asm/alternative-macros.h
> > +++ b/arch/riscv/include/asm/alternative-macros.h
> > @@ -7,11 +7,11 @@
> > #ifdef __ASSEMBLY__
> >
> > .macro ALT_ENTRY oldptr newptr vendor_id errata_id new_len
> > - RISCV_PTR \oldptr
> > - RISCV_PTR \newptr
> > - REG_ASM \vendor_id
> > - REG_ASM \new_len
> > - .word \errata_id
> > + .long \oldptr - .
> > + .long \newptr - .
> > + .short \vendor_id
> > + .short \new_len
> > + .long \errata_id
> > .endm
> >
> > .macro ALT_NEW_CONTENT vendor_id, errata_id, enable = 1, new_c : vararg
> > @@ -75,11 +75,11 @@
> > #include <linux/stringify.h>
> >
> > #define ALT_ENTRY(oldptr, newptr, vendor_id, errata_id, newlen) \
> > - RISCV_PTR " " oldptr "\n" \
> > - RISCV_PTR " " newptr "\n" \
> > - REG_ASM " " vendor_id "\n" \
> > - REG_ASM " " newlen "\n" \
> > - ".word " errata_id "\n"
> > + ".long ((" oldptr ") - .) \n" \
> > + ".long ((" newptr ") - .) \n" \
> > + ".short " vendor_id "\n" \
> > + ".short " newlen "\n" \
> > + ".long " errata_id "\n"
> >
> > #define ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c) \
> > ".if " __stringify(enable) " == 1\n" \
> > diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h
> > index 33eae9541684..3baf32e05b46 100644
> > --- a/arch/riscv/include/asm/alternative.h
> > +++ b/arch/riscv/include/asm/alternative.h
> > @@ -33,12 +33,12 @@ void riscv_alternative_fix_jal(void *alt_ptr, unsigned int len,
> > int patch_offset);
> >
> > struct alt_entry {
> > - void *old_ptr; /* address of original instruciton or data */
> > - void *alt_ptr; /* address of replacement instruction or data */
> > - unsigned long vendor_id; /* cpu vendor id */
> > - unsigned long alt_len; /* The replacement size */
> > - unsigned int errata_id; /* The errata id */
> > -} __packed;
> > + s32 old_offset; /* offset to original instruciton or data */
> > + s32 alt_offset; /* offset to replacement instruction or data */
> > + u16 vendor_id; /* cpu vendor id */
> > + u16 alt_len; /* The replacement size */
> > + u32 errata_id; /* The errata id */
> > +};
> >
> > struct errata_checkfunc_id {
> > unsigned long vendor_id;
> > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> > index 6244be5cd94a..adeac90b1d8e 100644
> > --- a/arch/riscv/kernel/cpufeature.c
> > +++ b/arch/riscv/kernel/cpufeature.c
> > @@ -257,6 +257,7 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
> > unsigned int stage)
> > {
> > struct alt_entry *alt;
> > + void *oldptr, *updptr;
> >
> > if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
> > return;
> > @@ -270,17 +271,15 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
> > continue;
> > }
> >
> > + oldptr = (void *)&alt->old_offset + alt->old_offset;
> > + updptr = (void *)&alt->alt_offset + alt->alt_offset;
> > if (!__riscv_isa_extension_available(NULL, alt->errata_id))
> > continue;
> >
> > /* do the basic patching */
> > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> > - riscv_alternative_fix_auipc_jalr(alt->old_ptr,
> > - alt->alt_len,
> > - alt->old_ptr - alt->alt_ptr);
> > - riscv_alternative_fix_jal(alt->old_ptr,
> > - alt->alt_len,
> > - alt->old_ptr - alt->alt_ptr);
> > + patch_text_nosync(oldptr, updptr, alt->alt_len);
> > + riscv_alternative_fix_auipc_jalr(oldptr, alt->alt_len, oldptr - updptr);
> > + riscv_alternative_fix_jal(oldptr, alt->alt_len, oldptr - updptr);
> > }
> > }
> > #endif
> > --
> > 2.37.2
> >
>
>
> --
> Best Regards
> Guo Ren
On Mon, Dec 5, 2022 at 11:28 PM Jisheng Zhang <[email protected]> wrote:
>
> On Mon, Dec 05, 2022 at 08:51:41AM +0800, Guo Ren wrote:
> > On Mon, Dec 5, 2022 at 1:57 AM Jisheng Zhang <[email protected]> wrote:
> > >
> > > Instead of using absolute addresses for both the old instrucions and
> > > the alternative instructions, use offsets relative to the alt_entry
> > > values. So we can not only cut the size of the alternative entry, but
> > > also meet the prerequisite for patching alternatives in the vDSO,
> > > since absolute alternative entries are subject to dynamic relocation,
> > > which is incompatible with the vDSO building.
> > >
> > > Signed-off-by: Jisheng Zhang <[email protected]>
> > > ---
> > > arch/riscv/errata/sifive/errata.c | 4 +++-
> > > arch/riscv/errata/thead/errata.c | 11 ++++++++---
> > > arch/riscv/include/asm/alternative-macros.h | 20 ++++++++++----------
> > > arch/riscv/include/asm/alternative.h | 12 ++++++------
> > > arch/riscv/kernel/cpufeature.c | 13 ++++++-------
> > > 5 files changed, 33 insertions(+), 27 deletions(-)
> > >
> > > diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
> > > index 1031038423e7..0e537cdfd324 100644
> > > --- a/arch/riscv/errata/sifive/errata.c
> > > +++ b/arch/riscv/errata/sifive/errata.c
> > > @@ -107,7 +107,9 @@ void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
> > >
> > > tmp = (1U << alt->errata_id);
> > > if (cpu_req_errata & tmp) {
> > > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> > > + patch_text_nosync((void *)&alt->old_offset + alt->old_offset,
> > > + (void *)&alt->alt_offset + alt->alt_offset,
> > (void *)&alt->alt_offset + alt->alt_offset. ??!!
>
> Hi Guo,
>
> what's the problem? I can't catch your meaning, could you please proide
> more details?
Can you explain why:
alt->old_ptr = (void *)&alt->old_offset + alt->old_offset
| offset | <- &offset
| ... |
| value | <- ptr = &offset + offset
I don't make sense of the above.
>
> Thanks
>
> >
> > > + alt->alt_len);
> > > cpu_apply_errata |= tmp;
> > > }
> > > }
> > > diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
> > > index 21546937db39..2a6e335b5a32 100644
> > > --- a/arch/riscv/errata/thead/errata.c
> > > +++ b/arch/riscv/errata/thead/errata.c
> > > @@ -68,6 +68,7 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
> > > struct alt_entry *alt;
> > > u32 cpu_req_errata = thead_errata_probe(stage, archid, impid);
> > > u32 tmp;
> > > + void *oldptr, *updptr;
> > >
> > > for (alt = begin; alt < end; alt++) {
> > > if (alt->vendor_id != THEAD_VENDOR_ID)
> > > @@ -77,12 +78,16 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
> > >
> > > tmp = (1U << alt->errata_id);
> > > if (cpu_req_errata & tmp) {
> > > + oldptr = (void *)&alt->old_offset + alt->old_offset;
> > > + updptr = (void *)&alt->alt_offset + alt->alt_offset;
> > > +
> > > /* On vm-alternatives, the mmu isn't running yet */
> > > if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
> > > - memcpy((void *)__pa_symbol(alt->old_ptr),
> > > - (void *)__pa_symbol(alt->alt_ptr), alt->alt_len);
> > > + memcpy((void *)__pa_symbol(oldptr),
> > > + (void *)__pa_symbol(updptr),
> > > + alt->alt_len);
> > > else
> > > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> > > + patch_text_nosync(oldptr, updptr, alt->alt_len);
> > > }
> > > }
> > >
> > > diff --git a/arch/riscv/include/asm/alternative-macros.h b/arch/riscv/include/asm/alternative-macros.h
> > > index ec2f3f1b836f..dd40727bc859 100644
> > > --- a/arch/riscv/include/asm/alternative-macros.h
> > > +++ b/arch/riscv/include/asm/alternative-macros.h
> > > @@ -7,11 +7,11 @@
> > > #ifdef __ASSEMBLY__
> > >
> > > .macro ALT_ENTRY oldptr newptr vendor_id errata_id new_len
> > > - RISCV_PTR \oldptr
> > > - RISCV_PTR \newptr
> > > - REG_ASM \vendor_id
> > > - REG_ASM \new_len
> > > - .word \errata_id
> > > + .long \oldptr - .
> > > + .long \newptr - .
> > > + .short \vendor_id
> > > + .short \new_len
> > > + .long \errata_id
> > > .endm
> > >
> > > .macro ALT_NEW_CONTENT vendor_id, errata_id, enable = 1, new_c : vararg
> > > @@ -75,11 +75,11 @@
> > > #include <linux/stringify.h>
> > >
> > > #define ALT_ENTRY(oldptr, newptr, vendor_id, errata_id, newlen) \
> > > - RISCV_PTR " " oldptr "\n" \
> > > - RISCV_PTR " " newptr "\n" \
> > > - REG_ASM " " vendor_id "\n" \
> > > - REG_ASM " " newlen "\n" \
> > > - ".word " errata_id "\n"
> > > + ".long ((" oldptr ") - .) \n" \
> > > + ".long ((" newptr ") - .) \n" \
> > > + ".short " vendor_id "\n" \
> > > + ".short " newlen "\n" \
> > > + ".long " errata_id "\n"
> > >
> > > #define ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c) \
> > > ".if " __stringify(enable) " == 1\n" \
> > > diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h
> > > index 33eae9541684..3baf32e05b46 100644
> > > --- a/arch/riscv/include/asm/alternative.h
> > > +++ b/arch/riscv/include/asm/alternative.h
> > > @@ -33,12 +33,12 @@ void riscv_alternative_fix_jal(void *alt_ptr, unsigned int len,
> > > int patch_offset);
> > >
> > > struct alt_entry {
> > > - void *old_ptr; /* address of original instruciton or data */
> > > - void *alt_ptr; /* address of replacement instruction or data */
> > > - unsigned long vendor_id; /* cpu vendor id */
> > > - unsigned long alt_len; /* The replacement size */
> > > - unsigned int errata_id; /* The errata id */
> > > -} __packed;
> > > + s32 old_offset; /* offset to original instruciton or data */
> > > + s32 alt_offset; /* offset to replacement instruction or data */
> > > + u16 vendor_id; /* cpu vendor id */
> > > + u16 alt_len; /* The replacement size */
> > > + u32 errata_id; /* The errata id */
> > > +};
> > >
> > > struct errata_checkfunc_id {
> > > unsigned long vendor_id;
> > > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> > > index 6244be5cd94a..adeac90b1d8e 100644
> > > --- a/arch/riscv/kernel/cpufeature.c
> > > +++ b/arch/riscv/kernel/cpufeature.c
> > > @@ -257,6 +257,7 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
> > > unsigned int stage)
> > > {
> > > struct alt_entry *alt;
> > > + void *oldptr, *updptr;
> > >
> > > if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
> > > return;
> > > @@ -270,17 +271,15 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
> > > continue;
> > > }
> > >
> > > + oldptr = (void *)&alt->old_offset + alt->old_offset;
> > > + updptr = (void *)&alt->alt_offset + alt->alt_offset;
> > > if (!__riscv_isa_extension_available(NULL, alt->errata_id))
> > > continue;
> > >
> > > /* do the basic patching */
> > > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> > > - riscv_alternative_fix_auipc_jalr(alt->old_ptr,
> > > - alt->alt_len,
> > > - alt->old_ptr - alt->alt_ptr);
> > > - riscv_alternative_fix_jal(alt->old_ptr,
> > > - alt->alt_len,
> > > - alt->old_ptr - alt->alt_ptr);
> > > + patch_text_nosync(oldptr, updptr, alt->alt_len);
> > > + riscv_alternative_fix_auipc_jalr(oldptr, alt->alt_len, oldptr - updptr);
> > > + riscv_alternative_fix_jal(oldptr, alt->alt_len, oldptr - updptr);
> > > }
> > > }
> > > #endif
> > > --
> > > 2.37.2
> > >
> >
> >
> > --
> > Best Regards
> > Guo Ren
--
Best Regards
Guo Ren
On Tue, Dec 06, 2022 at 12:34:40PM +0800, Guo Ren wrote:
> On Mon, Dec 5, 2022 at 11:28 PM Jisheng Zhang <[email protected]> wrote:
> >
> > On Mon, Dec 05, 2022 at 08:51:41AM +0800, Guo Ren wrote:
> > > On Mon, Dec 5, 2022 at 1:57 AM Jisheng Zhang <[email protected]> wrote:
> > > >
> > > > Instead of using absolute addresses for both the old instrucions and
> > > > the alternative instructions, use offsets relative to the alt_entry
> > > > values. So we can not only cut the size of the alternative entry, but
> > > > also meet the prerequisite for patching alternatives in the vDSO,
> > > > since absolute alternative entries are subject to dynamic relocation,
> > > > which is incompatible with the vDSO building.
> > > >
> > > > Signed-off-by: Jisheng Zhang <[email protected]>
> > > > ---
> > > > arch/riscv/errata/sifive/errata.c | 4 +++-
> > > > arch/riscv/errata/thead/errata.c | 11 ++++++++---
> > > > arch/riscv/include/asm/alternative-macros.h | 20 ++++++++++----------
> > > > arch/riscv/include/asm/alternative.h | 12 ++++++------
> > > > arch/riscv/kernel/cpufeature.c | 13 ++++++-------
> > > > 5 files changed, 33 insertions(+), 27 deletions(-)
> > > >
> > > > diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
> > > > index 1031038423e7..0e537cdfd324 100644
> > > > --- a/arch/riscv/errata/sifive/errata.c
> > > > +++ b/arch/riscv/errata/sifive/errata.c
> > > > @@ -107,7 +107,9 @@ void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
> > > >
> > > > tmp = (1U << alt->errata_id);
> > > > if (cpu_req_errata & tmp) {
> > > > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> > > > + patch_text_nosync((void *)&alt->old_offset + alt->old_offset,
> > > > + (void *)&alt->alt_offset + alt->alt_offset,
> > > (void *)&alt->alt_offset + alt->alt_offset. ??!!
> >
> > Hi Guo,
> >
> > what's the problem? I can't catch your meaning, could you please proide
> > more details?
> Can you explain why:
>
> alt->old_ptr = (void *)&alt->old_offset + alt->old_offset
Hi,
when constructing the alt entry, we save the offset in
then entry as below:
.long \oldptr - .
So we can restore the old_ptr by &alt->old_offset + alt->old_offset
Thanks
>
> | offset | <- &offset
> | ... |
> | value | <- ptr = &offset + offset
>
> I don't make sense of the above.
>
> >
> > Thanks
> >
> > >
> > > > + alt->alt_len);
> > > > cpu_apply_errata |= tmp;
> > > > }
> > > > }
> > > > diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
> > > > index 21546937db39..2a6e335b5a32 100644
> > > > --- a/arch/riscv/errata/thead/errata.c
> > > > +++ b/arch/riscv/errata/thead/errata.c
> > > > @@ -68,6 +68,7 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
> > > > struct alt_entry *alt;
> > > > u32 cpu_req_errata = thead_errata_probe(stage, archid, impid);
> > > > u32 tmp;
> > > > + void *oldptr, *updptr;
> > > >
> > > > for (alt = begin; alt < end; alt++) {
> > > > if (alt->vendor_id != THEAD_VENDOR_ID)
> > > > @@ -77,12 +78,16 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
> > > >
> > > > tmp = (1U << alt->errata_id);
> > > > if (cpu_req_errata & tmp) {
> > > > + oldptr = (void *)&alt->old_offset + alt->old_offset;
> > > > + updptr = (void *)&alt->alt_offset + alt->alt_offset;
> > > > +
> > > > /* On vm-alternatives, the mmu isn't running yet */
> > > > if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
> > > > - memcpy((void *)__pa_symbol(alt->old_ptr),
> > > > - (void *)__pa_symbol(alt->alt_ptr), alt->alt_len);
> > > > + memcpy((void *)__pa_symbol(oldptr),
> > > > + (void *)__pa_symbol(updptr),
> > > > + alt->alt_len);
> > > > else
> > > > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> > > > + patch_text_nosync(oldptr, updptr, alt->alt_len);
> > > > }
> > > > }
> > > >
> > > > diff --git a/arch/riscv/include/asm/alternative-macros.h b/arch/riscv/include/asm/alternative-macros.h
> > > > index ec2f3f1b836f..dd40727bc859 100644
> > > > --- a/arch/riscv/include/asm/alternative-macros.h
> > > > +++ b/arch/riscv/include/asm/alternative-macros.h
> > > > @@ -7,11 +7,11 @@
> > > > #ifdef __ASSEMBLY__
> > > >
> > > > .macro ALT_ENTRY oldptr newptr vendor_id errata_id new_len
> > > > - RISCV_PTR \oldptr
> > > > - RISCV_PTR \newptr
> > > > - REG_ASM \vendor_id
> > > > - REG_ASM \new_len
> > > > - .word \errata_id
> > > > + .long \oldptr - .
> > > > + .long \newptr - .
> > > > + .short \vendor_id
> > > > + .short \new_len
> > > > + .long \errata_id
> > > > .endm
> > > >
> > > > .macro ALT_NEW_CONTENT vendor_id, errata_id, enable = 1, new_c : vararg
> > > > @@ -75,11 +75,11 @@
> > > > #include <linux/stringify.h>
> > > >
> > > > #define ALT_ENTRY(oldptr, newptr, vendor_id, errata_id, newlen) \
> > > > - RISCV_PTR " " oldptr "\n" \
> > > > - RISCV_PTR " " newptr "\n" \
> > > > - REG_ASM " " vendor_id "\n" \
> > > > - REG_ASM " " newlen "\n" \
> > > > - ".word " errata_id "\n"
> > > > + ".long ((" oldptr ") - .) \n" \
> > > > + ".long ((" newptr ") - .) \n" \
> > > > + ".short " vendor_id "\n" \
> > > > + ".short " newlen "\n" \
> > > > + ".long " errata_id "\n"
> > > >
> > > > #define ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c) \
> > > > ".if " __stringify(enable) " == 1\n" \
> > > > diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h
> > > > index 33eae9541684..3baf32e05b46 100644
> > > > --- a/arch/riscv/include/asm/alternative.h
> > > > +++ b/arch/riscv/include/asm/alternative.h
> > > > @@ -33,12 +33,12 @@ void riscv_alternative_fix_jal(void *alt_ptr, unsigned int len,
> > > > int patch_offset);
> > > >
> > > > struct alt_entry {
> > > > - void *old_ptr; /* address of original instruciton or data */
> > > > - void *alt_ptr; /* address of replacement instruction or data */
> > > > - unsigned long vendor_id; /* cpu vendor id */
> > > > - unsigned long alt_len; /* The replacement size */
> > > > - unsigned int errata_id; /* The errata id */
> > > > -} __packed;
> > > > + s32 old_offset; /* offset to original instruciton or data */
> > > > + s32 alt_offset; /* offset to replacement instruction or data */
> > > > + u16 vendor_id; /* cpu vendor id */
> > > > + u16 alt_len; /* The replacement size */
> > > > + u32 errata_id; /* The errata id */
> > > > +};
> > > >
> > > > struct errata_checkfunc_id {
> > > > unsigned long vendor_id;
> > > > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> > > > index 6244be5cd94a..adeac90b1d8e 100644
> > > > --- a/arch/riscv/kernel/cpufeature.c
> > > > +++ b/arch/riscv/kernel/cpufeature.c
> > > > @@ -257,6 +257,7 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
> > > > unsigned int stage)
> > > > {
> > > > struct alt_entry *alt;
> > > > + void *oldptr, *updptr;
> > > >
> > > > if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
> > > > return;
> > > > @@ -270,17 +271,15 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
> > > > continue;
> > > > }
> > > >
> > > > + oldptr = (void *)&alt->old_offset + alt->old_offset;
> > > > + updptr = (void *)&alt->alt_offset + alt->alt_offset;
> > > > if (!__riscv_isa_extension_available(NULL, alt->errata_id))
> > > > continue;
> > > >
> > > > /* do the basic patching */
> > > > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> > > > - riscv_alternative_fix_auipc_jalr(alt->old_ptr,
> > > > - alt->alt_len,
> > > > - alt->old_ptr - alt->alt_ptr);
> > > > - riscv_alternative_fix_jal(alt->old_ptr,
> > > > - alt->alt_len,
> > > > - alt->old_ptr - alt->alt_ptr);
> > > > + patch_text_nosync(oldptr, updptr, alt->alt_len);
> > > > + riscv_alternative_fix_auipc_jalr(oldptr, alt->alt_len, oldptr - updptr);
> > > > + riscv_alternative_fix_jal(oldptr, alt->alt_len, oldptr - updptr);
> > > > }
> > > > }
> > > > #endif
> > > > --
> > > > 2.37.2
> > > >
> > >
> > >
> > > --
> > > Best Regards
> > > Guo Ren
>
>
>
> --
> Best Regards
> Guo Ren
Hey Jisheng, Guo Ren,
On Tue, Dec 06, 2022 at 10:50:37PM +0800, Jisheng Zhang wrote:
> On Tue, Dec 06, 2022 at 12:34:40PM +0800, Guo Ren wrote:
> > On Mon, Dec 5, 2022 at 11:28 PM Jisheng Zhang <[email protected]> wrote:
> > > On Mon, Dec 05, 2022 at 08:51:41AM +0800, Guo Ren wrote:
> > > > On Mon, Dec 5, 2022 at 1:57 AM Jisheng Zhang <[email protected]> wrote:
> > > > >
> > > > > Instead of using absolute addresses for both the old instrucions and
> > > > > the alternative instructions, use offsets relative to the alt_entry
> > > > > values. So we can not only cut the size of the alternative entry, but
"This not only cuts"
> > > > > also meet the prerequisite for patching alternatives in the vDSO,
> > > > > since absolute alternative entries are subject to dynamic relocation,
> > > > > which is incompatible with the vDSO building.
I do this this is in the wrong order though, saving on size is
secondary to enabling their use in the vdso?
> > > > >
> > > > > Signed-off-by: Jisheng Zhang <[email protected]>
> > > > > ---
> > > > > arch/riscv/errata/sifive/errata.c | 4 +++-
> > > > > arch/riscv/errata/thead/errata.c | 11 ++++++++---
> > > > > arch/riscv/include/asm/alternative-macros.h | 20 ++++++++++----------
> > > > > arch/riscv/include/asm/alternative.h | 12 ++++++------
> > > > > arch/riscv/kernel/cpufeature.c | 13 ++++++-------
> > > > > 5 files changed, 33 insertions(+), 27 deletions(-)
> > > > >
> > > > > diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
> > > > > index 1031038423e7..0e537cdfd324 100644
> > > > > --- a/arch/riscv/errata/sifive/errata.c
> > > > > +++ b/arch/riscv/errata/sifive/errata.c
> > > > > @@ -107,7 +107,9 @@ void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
> > > > >
> > > > > tmp = (1U << alt->errata_id);
> > > > > if (cpu_req_errata & tmp) {
> > > > > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
> > > > > + patch_text_nosync((void *)&alt->old_offset + alt->old_offset,
> > > > > + (void *)&alt->alt_offset + alt->alt_offset,
> > > > (void *)&alt->alt_offset + alt->alt_offset. ??!!
> > >
> > > Hi Guo,
> > >
> > > what's the problem? I can't catch your meaning, could you please proide
> > > more details?
> > Can you explain why:
> >
> > alt->old_ptr = (void *)&alt->old_offset + alt->old_offset
>
> Hi,
>
> when constructing the alt entry, we save the offset in
> then entry as below:
>
> .long \oldptr - .
>
> So we can restore the old_ptr by &alt->old_offset + alt->old_offset
Please correct me if I have misunderstood, but for stuff like this I
find it useful to kinda summarise a bit and figure out for myself what
is going on..
As things stand, we have absolute "locations" for the alternative and
"old" instructions/data/functions. Your commit is converting us over to
use offsets. The code that patches in the alternatives needs to have
absolute addresses though, so you need to be able to, effectively,
reverse engineer those from the offset.
You do this by taking the address of the offset & adding the offset to
the address before casting to (void *). This works, because the offset
is the offset from the alt_entry data structure to the alternative?
I hope I am in the right ballpark there haha, but I do think that this
really needs a comment explaining what it is doing. Maybe extract that
operation into some sort of macro in alternatives.h so the operation is
done in a central location & you can leave the comment there?
That'd make it at least more manageable for us mere mortals who can just
do something like
patch_text_nosync(ALT_OFFSET_ADDRESS(alt->old_offset),
ALT_OFFSET_ADDRESS(alt->alt_offset),
alt->alt_len);
when we have to go an add some alternatives..
> >
> > | offset | <- &offset
> > | ... |
> > | value | <- ptr = &offset + offset
> >
> > I don't make sense of the above.
> >
> > >
> > > Thanks
> > >
> > > >
> > > > > + alt->alt_len);
> > > > > cpu_apply_errata |= tmp;
> > > > > }
> > > > > }
> > > > > diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
> > > > > index 21546937db39..2a6e335b5a32 100644
> > > > > --- a/arch/riscv/errata/thead/errata.c
> > > > > +++ b/arch/riscv/errata/thead/errata.c
> > > > > @@ -68,6 +68,7 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
> > > > > struct alt_entry *alt;
> > > > > u32 cpu_req_errata = thead_errata_probe(stage, archid, impid);
> > > > > u32 tmp;
> > > > > + void *oldptr, *updptr;
Why mix the terminology with "upd" instead of "alt"?
> > > > >
> > > > > for (alt = begin; alt < end; alt++) {
> > > > > if (alt->vendor_id != THEAD_VENDOR_ID)
> > > > > struct alt_entry {
> > > > > - void *old_ptr; /* address of original instruciton or data */
> > > > > - void *alt_ptr; /* address of replacement instruction or data */
> > > > > - unsigned long vendor_id; /* cpu vendor id */
> > > > > - unsigned long alt_len; /* The replacement size */
> > > > > - unsigned int errata_id; /* The errata id */
> > > > > -} __packed;
> > > > > + s32 old_offset; /* offset to original instruciton or data */
> > > > > + s32 alt_offset; /* offset to replacement instruction or data */
Perhaps also this comment could be expanded on to specify what it is an
offset *from* as well as to?
> > > > > + u16 vendor_id; /* cpu vendor id */
> > > > > + u16 alt_len; /* The replacement size */
> > > > > + u32 errata_id; /* The errata id */
> > > > > +};
I hope I didn't make a hames of trying to understand what you were
doing, but please let me know what I have undoubtedly got mixed up on!
Thanks,
Conor.