[PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[Shea Levy]

Signed-off-by: Shea Levy <shea@shealevy.com>
---

Note that this patch worked in my old modules patchset and seems to be
working now, but my kernel boot locks up on top of
riscv-for-linus-4.17-mw0 and I don't know if it's due to this patch or
something else that's changed in the mean time.

---
 arch/riscv/include/asm/pgtable.h |  9 +++++++++
 arch/riscv/kernel/module.c       | 11 +++++++++++
 2 files changed, 20 insertions(+)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 16301966d65b..b08ded13364a 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -25,6 +25,7 @@
 #include <asm/page.h>
 #include <asm/tlbflush.h>
 #include <linux/mm_types.h>
+#include <linux/sizes.h>
 
 #ifdef CONFIG_64BIT
 #include <asm/pgtable-64.h>
@@ -425,6 +426,14 @@ static inline void pgtable_cache_init(void)
 #define TASK_SIZE VMALLOC_START
 #endif
 
+/*
+ * The module space lives between the addresses given by TASK_SIZE
+ * and PAGE_OFFSET - it must be within 2G of the kernel text.
+ */
+#define MODULES_SIZE		(SZ_128M)
+#define MODULES_VADDR		(PAGE_OFFSET - MODULES_SIZE)
+#define MODULES_END		(VMALLOC_END)
+
 #include <asm-generic/pgtable.h>
 
 #endif /* !__ASSEMBLY__ */
diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
index 5dddba301d0a..1b382c7de095 100644
--- a/arch/riscv/kernel/module.c
+++ b/arch/riscv/kernel/module.c
@@ -16,6 +16,8 @@
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/moduleloader.h>
+#include <linux/vmalloc.h>
+#include <asm/pgtable.h>
 
 static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
 {
@@ -382,3 +384,12 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 
 	return 0;
 }
+
+void *module_alloc(unsigned long size)
+{
+	return __vmalloc_node_range(size, 1, MODULES_VADDR,
+				    MODULES_END, GFP_KERNEL,
+				    PAGE_KERNEL_EXEC, 0,
+				    NUMA_NO_NODE,
+				    __builtin_return_address(0));
+}
-- 
2.16.2

[PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[Shea Levy]

Hi Palmer,

Shea Levy <shea@shealevy.com> writes:

> Signed-off-by: Shea Levy <shea@shealevy.com>
> ---
>
> Note that this patch worked in my old modules patchset and seems to be
> working now, but my kernel boot locks up on top of
> riscv-for-linus-4.17-mw0 and I don't know if it's due to this patch or
> something else that's changed in the mean time.
>
> ---
>  arch/riscv/include/asm/pgtable.h |  9 +++++++++
>  arch/riscv/kernel/module.c       | 11 +++++++++++
>  2 files changed, 20 insertions(+)
>
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 16301966d65b..b08ded13364a 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -25,6 +25,7 @@
>  #include <asm/page.h>
>  #include <asm/tlbflush.h>
>  #include <linux/mm_types.h>
> +#include <linux/sizes.h>
>  
>  #ifdef CONFIG_64BIT
>  #include <asm/pgtable-64.h>
> @@ -425,6 +426,14 @@ static inline void pgtable_cache_init(void)
>  #define TASK_SIZE VMALLOC_START
>  #endif
>  
> +/*
> + * The module space lives between the addresses given by TASK_SIZE
> + * and PAGE_OFFSET - it must be within 2G of the kernel text.
> + */
> +#define MODULES_SIZE		(SZ_128M)
> +#define MODULES_VADDR		(PAGE_OFFSET - MODULES_SIZE)
> +#define MODULES_END		(VMALLOC_END)
> +
>  #include <asm-generic/pgtable.h>
>  
>  #endif /* !__ASSEMBLY__ */
> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> index 5dddba301d0a..1b382c7de095 100644
> --- a/arch/riscv/kernel/module.c
> +++ b/arch/riscv/kernel/module.c
> @@ -16,6 +16,8 @@
>  #include <linux/err.h>
>  #include <linux/errno.h>
>  #include <linux/moduleloader.h>
> +#include <linux/vmalloc.h>
> +#include <asm/pgtable.h>
>  
>  static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
>  {
> @@ -382,3 +384,12 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
>  
>  	return 0;
>  }
> +
> +void *module_alloc(unsigned long size)
> +{
> +	return __vmalloc_node_range(size, 1, MODULES_VADDR,
> +				    MODULES_END, GFP_KERNEL,
> +				    PAGE_KERNEL_EXEC, 0,
> +				    NUMA_NO_NODE,
> +				    __builtin_return_address(0));
> +}
> -- 
> 2.16.2

Any thoughts on this?

Thanks,
Shea
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[PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[Palmer Dabbelt]

On Sun, 22 Apr 2018 05:53:56 PDT (-0700), shea at shealevy.com wrote:
> Hi Palmer,
>
> Shea Levy <shea@shealevy.com> writes:
>
>> Signed-off-by: Shea Levy <shea@shealevy.com>
>> ---
>>
>> Note that this patch worked in my old modules patchset and seems to be
>> working now, but my kernel boot locks up on top of
>> riscv-for-linus-4.17-mw0 and I don't know if it's due to this patch or
>> something else that's changed in the mean time.
>>
>> ---
>>  arch/riscv/include/asm/pgtable.h |  9 +++++++++
>>  arch/riscv/kernel/module.c       | 11 +++++++++++
>>  2 files changed, 20 insertions(+)
>>
>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>> index 16301966d65b..b08ded13364a 100644
>> --- a/arch/riscv/include/asm/pgtable.h
>> +++ b/arch/riscv/include/asm/pgtable.h
>> @@ -25,6 +25,7 @@
>>  #include <asm/page.h>
>>  #include <asm/tlbflush.h>
>>  #include <linux/mm_types.h>
>> +#include <linux/sizes.h>
>>  
>>  #ifdef CONFIG_64BIT
>>  #include <asm/pgtable-64.h>
>> @@ -425,6 +426,14 @@ static inline void pgtable_cache_init(void)
>>  #define TASK_SIZE VMALLOC_START
>>  #endif
>>  
>> +/*
>> + * The module space lives between the addresses given by TASK_SIZE
>> + * and PAGE_OFFSET - it must be within 2G of the kernel text.
>> + */
>> +#define MODULES_SIZE		(SZ_128M)
>> +#define MODULES_VADDR		(PAGE_OFFSET - MODULES_SIZE)
>> +#define MODULES_END		(VMALLOC_END)
>> +
>>  #include <asm-generic/pgtable.h>
>>  
>>  #endif /* !__ASSEMBLY__ */
>> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
>> index 5dddba301d0a..1b382c7de095 100644
>> --- a/arch/riscv/kernel/module.c
>> +++ b/arch/riscv/kernel/module.c
>> @@ -16,6 +16,8 @@
>>  #include <linux/err.h>
>>  #include <linux/errno.h>
>>  #include <linux/moduleloader.h>
>> +#include <linux/vmalloc.h>
>> +#include <asm/pgtable.h>
>>  
>>  static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
>>  {
>> @@ -382,3 +384,12 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
>>  
>>  	return 0;
>>  }
>> +
>> +void *module_alloc(unsigned long size)
>> +{
>> +	return __vmalloc_node_range(size, 1, MODULES_VADDR,
>> +				    MODULES_END, GFP_KERNEL,
>> +				    PAGE_KERNEL_EXEC, 0,
>> +				    NUMA_NO_NODE,
>> +				    __builtin_return_address(0));
>> +}
>> -- 
>> 2.16.2
>
> Any thoughts on this?

The concept looks good, but does this actually keep the modules within 2GiB of 
the text if PAGE_OFFSET is large?

[PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[Shea Levy]

Hi Palmer,

Palmer Dabbelt <palmer@sifive.com> writes:

> On Sun, 22 Apr 2018 05:53:56 PDT (-0700), shea at shealevy.com wrote:
>> Hi Palmer,
>>
>> Shea Levy <shea@shealevy.com> writes:
>>
>>> Signed-off-by: Shea Levy <shea@shealevy.com>
>>> ---
>>>
>>> Note that this patch worked in my old modules patchset and seems to be
>>> working now, but my kernel boot locks up on top of
>>> riscv-for-linus-4.17-mw0 and I don't know if it's due to this patch or
>>> something else that's changed in the mean time.
>>>
>>> ---
>>>  arch/riscv/include/asm/pgtable.h |  9 +++++++++
>>>  arch/riscv/kernel/module.c       | 11 +++++++++++
>>>  2 files changed, 20 insertions(+)
>>>
>>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>>> index 16301966d65b..b08ded13364a 100644
>>> --- a/arch/riscv/include/asm/pgtable.h
>>> +++ b/arch/riscv/include/asm/pgtable.h
>>> @@ -25,6 +25,7 @@
>>>  #include <asm/page.h>
>>>  #include <asm/tlbflush.h>
>>>  #include <linux/mm_types.h>
>>> +#include <linux/sizes.h>
>>>  
>>>  #ifdef CONFIG_64BIT
>>>  #include <asm/pgtable-64.h>
>>> @@ -425,6 +426,14 @@ static inline void pgtable_cache_init(void)
>>>  #define TASK_SIZE VMALLOC_START
>>>  #endif
>>>  
>>> +/*
>>> + * The module space lives between the addresses given by TASK_SIZE
>>> + * and PAGE_OFFSET - it must be within 2G of the kernel text.
>>> + */
>>> +#define MODULES_SIZE		(SZ_128M)
>>> +#define MODULES_VADDR		(PAGE_OFFSET - MODULES_SIZE)
>>> +#define MODULES_END		(VMALLOC_END)
>>> +
>>>  #include <asm-generic/pgtable.h>
>>>  
>>>  #endif /* !__ASSEMBLY__ */
>>> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
>>> index 5dddba301d0a..1b382c7de095 100644
>>> --- a/arch/riscv/kernel/module.c
>>> +++ b/arch/riscv/kernel/module.c
>>> @@ -16,6 +16,8 @@
>>>  #include <linux/err.h>
>>>  #include <linux/errno.h>
>>>  #include <linux/moduleloader.h>
>>> +#include <linux/vmalloc.h>
>>> +#include <asm/pgtable.h>
>>>  
>>>  static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
>>>  {
>>> @@ -382,3 +384,12 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
>>>  
>>>  	return 0;
>>>  }
>>> +
>>> +void *module_alloc(unsigned long size)
>>> +{
>>> +	return __vmalloc_node_range(size, 1, MODULES_VADDR,
>>> +				    MODULES_END, GFP_KERNEL,
>>> +				    PAGE_KERNEL_EXEC, 0,
>>> +				    NUMA_NO_NODE,
>>> +				    __builtin_return_address(0));
>>> +}
>>> -- 
>>> 2.16.2
>>
>> Any thoughts on this?
>
> The concept looks good, but does this actually keep the modules within 2GiB of 
> the text if PAGE_OFFSET is large?

It's been some time since I wrote this, but I thought PAGE_OFFSET was
where the kernel text *started*? So unless the text itself is bigger
than 2G - 128 M, in which case we're SOL anyway, it seems like this
should work. Is there something better we can do, without a large memory
model?

Thanks,
Shea
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[PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[Shea Levy]

Hi Palmer,

Shea Levy <shea@shealevy.com> writes:

> Hi Palmer,
>
> Palmer Dabbelt <palmer@sifive.com> writes:
>
>> On Sun, 22 Apr 2018 05:53:56 PDT (-0700), shea at shealevy.com wrote:
>>> Hi Palmer,
>>>
>>> Shea Levy <shea@shealevy.com> writes:
>>>
>>>> Signed-off-by: Shea Levy <shea@shealevy.com>
>>>> ---
>>>>
>>>> Note that this patch worked in my old modules patchset and seems to be
>>>> working now, but my kernel boot locks up on top of
>>>> riscv-for-linus-4.17-mw0 and I don't know if it's due to this patch or
>>>> something else that's changed in the mean time.
>>>>
>>>> ---
>>>>  arch/riscv/include/asm/pgtable.h |  9 +++++++++
>>>>  arch/riscv/kernel/module.c       | 11 +++++++++++
>>>>  2 files changed, 20 insertions(+)
>>>>
>>>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>>>> index 16301966d65b..b08ded13364a 100644
>>>> --- a/arch/riscv/include/asm/pgtable.h
>>>> +++ b/arch/riscv/include/asm/pgtable.h
>>>> @@ -25,6 +25,7 @@
>>>>  #include <asm/page.h>
>>>>  #include <asm/tlbflush.h>
>>>>  #include <linux/mm_types.h>
>>>> +#include <linux/sizes.h>
>>>>  
>>>>  #ifdef CONFIG_64BIT
>>>>  #include <asm/pgtable-64.h>
>>>> @@ -425,6 +426,14 @@ static inline void pgtable_cache_init(void)
>>>>  #define TASK_SIZE VMALLOC_START
>>>>  #endif
>>>>  
>>>> +/*
>>>> + * The module space lives between the addresses given by TASK_SIZE
>>>> + * and PAGE_OFFSET - it must be within 2G of the kernel text.
>>>> + */
>>>> +#define MODULES_SIZE		(SZ_128M)
>>>> +#define MODULES_VADDR		(PAGE_OFFSET - MODULES_SIZE)
>>>> +#define MODULES_END		(VMALLOC_END)
>>>> +
>>>>  #include <asm-generic/pgtable.h>
>>>>  
>>>>  #endif /* !__ASSEMBLY__ */
>>>> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
>>>> index 5dddba301d0a..1b382c7de095 100644
>>>> --- a/arch/riscv/kernel/module.c
>>>> +++ b/arch/riscv/kernel/module.c
>>>> @@ -16,6 +16,8 @@
>>>>  #include <linux/err.h>
>>>>  #include <linux/errno.h>
>>>>  #include <linux/moduleloader.h>
>>>> +#include <linux/vmalloc.h>
>>>> +#include <asm/pgtable.h>
>>>>  
>>>>  static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
>>>>  {
>>>> @@ -382,3 +384,12 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
>>>>  
>>>>  	return 0;
>>>>  }
>>>> +
>>>> +void *module_alloc(unsigned long size)
>>>> +{
>>>> +	return __vmalloc_node_range(size, 1, MODULES_VADDR,
>>>> +				    MODULES_END, GFP_KERNEL,
>>>> +				    PAGE_KERNEL_EXEC, 0,
>>>> +				    NUMA_NO_NODE,
>>>> +				    __builtin_return_address(0));
>>>> +}
>>>> -- 
>>>> 2.16.2
>>>
>>> Any thoughts on this?
>>
>> The concept looks good, but does this actually keep the modules within 2GiB of 
>> the text if PAGE_OFFSET is large?
>
> It's been some time since I wrote this, but I thought PAGE_OFFSET was
> where the kernel text *started*? So unless the text itself is bigger
> than 2G - 128 M, in which case we're SOL anyway, it seems like this
> should work. Is there something better we can do, without a large memory
> model?
>
> Thanks,
> Shea

Any further thoughts on this?

Thanks,
Shea
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Re: [PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[Björn Töpel]

On Wed, 9 May 2018 at 13:22, Shea Levy <shea@shealevy.com> wrote:
>
> Hi Palmer,
>
> Shea Levy <shea@shealevy.com> writes:
>
> > Hi Palmer,
> >
> > Palmer Dabbelt <palmer@sifive.com> writes:
> >
> >> On Sun, 22 Apr 2018 05:53:56 PDT (-0700), shea@shealevy.com wrote:
> >>> Hi Palmer,
> >>>
> >>> Shea Levy <shea@shealevy.com> writes:
> >>>
> >>>> Signed-off-by: Shea Levy <shea@shealevy.com>
> >>>> ---
> >>>>
> >>>> Note that this patch worked in my old modules patchset and seems to be
> >>>> working now, but my kernel boot locks up on top of
> >>>> riscv-for-linus-4.17-mw0 and I don't know if it's due to this patch or
> >>>> something else that's changed in the mean time.
> >>>>
> >>>> ---
> >>>>  arch/riscv/include/asm/pgtable.h |  9 +++++++++
> >>>>  arch/riscv/kernel/module.c       | 11 +++++++++++
> >>>>  2 files changed, 20 insertions(+)
> >>>>
> >>>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> >>>> index 16301966d65b..b08ded13364a 100644
> >>>> --- a/arch/riscv/include/asm/pgtable.h
> >>>> +++ b/arch/riscv/include/asm/pgtable.h
> >>>> @@ -25,6 +25,7 @@
> >>>>  #include <asm/page.h>
> >>>>  #include <asm/tlbflush.h>
> >>>>  #include <linux/mm_types.h>
> >>>> +#include <linux/sizes.h>
> >>>>
> >>>>  #ifdef CONFIG_64BIT
> >>>>  #include <asm/pgtable-64.h>
> >>>> @@ -425,6 +426,14 @@ static inline void pgtable_cache_init(void)
> >>>>  #define TASK_SIZE VMALLOC_START
> >>>>  #endif
> >>>>
> >>>> +/*
> >>>> + * The module space lives between the addresses given by TASK_SIZE
> >>>> + * and PAGE_OFFSET - it must be within 2G of the kernel text.
> >>>> + */
> >>>> +#define MODULES_SIZE              (SZ_128M)
> >>>> +#define MODULES_VADDR             (PAGE_OFFSET - MODULES_SIZE)
> >>>> +#define MODULES_END               (VMALLOC_END)
> >>>> +
> >>>>  #include <asm-generic/pgtable.h>
> >>>>
> >>>>  #endif /* !__ASSEMBLY__ */
> >>>> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> >>>> index 5dddba301d0a..1b382c7de095 100644
> >>>> --- a/arch/riscv/kernel/module.c
> >>>> +++ b/arch/riscv/kernel/module.c
> >>>> @@ -16,6 +16,8 @@
> >>>>  #include <linux/err.h>
> >>>>  #include <linux/errno.h>
> >>>>  #include <linux/moduleloader.h>
> >>>> +#include <linux/vmalloc.h>
> >>>> +#include <asm/pgtable.h>
> >>>>
> >>>>  static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
> >>>>  {
> >>>> @@ -382,3 +384,12 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
> >>>>
> >>>>    return 0;
> >>>>  }
> >>>> +
> >>>> +void *module_alloc(unsigned long size)
> >>>> +{
> >>>> +  return __vmalloc_node_range(size, 1, MODULES_VADDR,
> >>>> +                              MODULES_END, GFP_KERNEL,
> >>>> +                              PAGE_KERNEL_EXEC, 0,
> >>>> +                              NUMA_NO_NODE,
> >>>> +                              __builtin_return_address(0));
> >>>> +}
> >>>> --
> >>>> 2.16.2
> >>>
> >>> Any thoughts on this?
> >>
> >> The concept looks good, but does this actually keep the modules within 2GiB of
> >> the text if PAGE_OFFSET is large?
> >
> > It's been some time since I wrote this, but I thought PAGE_OFFSET was
> > where the kernel text *started*? So unless the text itself is bigger
> > than 2G - 128 M, in which case we're SOL anyway, it seems like this
> > should work. Is there something better we can do, without a large memory
> > model?
> >
> > Thanks,
> > Shea
>
> Any further thoughts on this?
>
> Thanks,
> Shea

Shea,

Waking up the dead (threads)!

I'm hacking on call improvements for the RISC-V BPF JIT.
module_alloc() is used under the hood of bpf_jit_binary_alloc(), which
in turn is used to allocate the JIT image. The current JIT
implementation has to to "load imm64 + jalr" to call kernel syms,
since the relative offset is >32b. With your patch, I can use regular
jal/auipc+jalr instead. IOW, it would be great if it could be merged.
;-) I'd prefer not having the patch in my BPF JIT series, since that
will go through a different tree than Paul's RV one.

Wdyt about brushing of the dust of the patch, and re-send it?


Thanks!
Björn

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Re: [PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[Shea Levy]

[-- Attachment #1.1: Type: text/plain, Size: 4652 bytes --]

Hi Björn,

Unfortunately I'm not sure what more is needed to get this in, and I'm
in the middle of a move and won't have easy access to my RISC-V setup
for testing. I don't think you can count on me for this one.

Thanks,
Shea

Björn Töpel <bjorn.topel@gmail.com> writes:

> On Wed, 9 May 2018 at 13:22, Shea Levy <shea@shealevy.com> wrote:
>>
>> Hi Palmer,
>>
>> Shea Levy <shea@shealevy.com> writes:
>>
>> > Hi Palmer,
>> >
>> > Palmer Dabbelt <palmer@sifive.com> writes:
>> >
>> >> On Sun, 22 Apr 2018 05:53:56 PDT (-0700), shea@shealevy.com wrote:
>> >>> Hi Palmer,
>> >>>
>> >>> Shea Levy <shea@shealevy.com> writes:
>> >>>
>> >>>> Signed-off-by: Shea Levy <shea@shealevy.com>
>> >>>> ---
>> >>>>
>> >>>> Note that this patch worked in my old modules patchset and seems to be
>> >>>> working now, but my kernel boot locks up on top of
>> >>>> riscv-for-linus-4.17-mw0 and I don't know if it's due to this patch or
>> >>>> something else that's changed in the mean time.
>> >>>>
>> >>>> ---
>> >>>>  arch/riscv/include/asm/pgtable.h |  9 +++++++++
>> >>>>  arch/riscv/kernel/module.c       | 11 +++++++++++
>> >>>>  2 files changed, 20 insertions(+)
>> >>>>
>> >>>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>> >>>> index 16301966d65b..b08ded13364a 100644
>> >>>> --- a/arch/riscv/include/asm/pgtable.h
>> >>>> +++ b/arch/riscv/include/asm/pgtable.h
>> >>>> @@ -25,6 +25,7 @@
>> >>>>  #include <asm/page.h>
>> >>>>  #include <asm/tlbflush.h>
>> >>>>  #include <linux/mm_types.h>
>> >>>> +#include <linux/sizes.h>
>> >>>>
>> >>>>  #ifdef CONFIG_64BIT
>> >>>>  #include <asm/pgtable-64.h>
>> >>>> @@ -425,6 +426,14 @@ static inline void pgtable_cache_init(void)
>> >>>>  #define TASK_SIZE VMALLOC_START
>> >>>>  #endif
>> >>>>
>> >>>> +/*
>> >>>> + * The module space lives between the addresses given by TASK_SIZE
>> >>>> + * and PAGE_OFFSET - it must be within 2G of the kernel text.
>> >>>> + */
>> >>>> +#define MODULES_SIZE              (SZ_128M)
>> >>>> +#define MODULES_VADDR             (PAGE_OFFSET - MODULES_SIZE)
>> >>>> +#define MODULES_END               (VMALLOC_END)
>> >>>> +
>> >>>>  #include <asm-generic/pgtable.h>
>> >>>>
>> >>>>  #endif /* !__ASSEMBLY__ */
>> >>>> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
>> >>>> index 5dddba301d0a..1b382c7de095 100644
>> >>>> --- a/arch/riscv/kernel/module.c
>> >>>> +++ b/arch/riscv/kernel/module.c
>> >>>> @@ -16,6 +16,8 @@
>> >>>>  #include <linux/err.h>
>> >>>>  #include <linux/errno.h>
>> >>>>  #include <linux/moduleloader.h>
>> >>>> +#include <linux/vmalloc.h>
>> >>>> +#include <asm/pgtable.h>
>> >>>>
>> >>>>  static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
>> >>>>  {
>> >>>> @@ -382,3 +384,12 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
>> >>>>
>> >>>>    return 0;
>> >>>>  }
>> >>>> +
>> >>>> +void *module_alloc(unsigned long size)
>> >>>> +{
>> >>>> +  return __vmalloc_node_range(size, 1, MODULES_VADDR,
>> >>>> +                              MODULES_END, GFP_KERNEL,
>> >>>> +                              PAGE_KERNEL_EXEC, 0,
>> >>>> +                              NUMA_NO_NODE,
>> >>>> +                              __builtin_return_address(0));
>> >>>> +}
>> >>>> --
>> >>>> 2.16.2
>> >>>
>> >>> Any thoughts on this?
>> >>
>> >> The concept looks good, but does this actually keep the modules within 2GiB of
>> >> the text if PAGE_OFFSET is large?
>> >
>> > It's been some time since I wrote this, but I thought PAGE_OFFSET was
>> > where the kernel text *started*? So unless the text itself is bigger
>> > than 2G - 128 M, in which case we're SOL anyway, it seems like this
>> > should work. Is there something better we can do, without a large memory
>> > model?
>> >
>> > Thanks,
>> > Shea
>>
>> Any further thoughts on this?
>>
>> Thanks,
>> Shea
>
> Shea,
>
> Waking up the dead (threads)!
>
> I'm hacking on call improvements for the RISC-V BPF JIT.
> module_alloc() is used under the hood of bpf_jit_binary_alloc(), which
> in turn is used to allocate the JIT image. The current JIT
> implementation has to to "load imm64 + jalr" to call kernel syms,
> since the relative offset is >32b. With your patch, I can use regular
> jal/auipc+jalr instead. IOW, it would be great if it could be merged.
> ;-) I'd prefer not having the patch in my BPF JIT series, since that
> will go through a different tree than Paul's RV one.
>
> Wdyt about brushing of the dust of the patch, and re-send it?
>
>
> Thanks!
> Björn

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Re: [PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[Björn Töpel]

On Tue, 26 Nov 2019 at 14:25, Shea Levy <shea@shealevy.com> wrote:
>
> Hi Björn,
>
> Unfortunately I'm not sure what more is needed to get this in, and I'm
> in the middle of a move and won't have easy access to my RISC-V setup
> for testing. I don't think you can count on me for this one.
>

Thanks for getting back quickly! No worries, I'll pick it up!


Cheers,
Björn

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Re: [PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[Björn Töpel]

On Tue, 26 Nov 2019 at 17:43, Björn Töpel <bjorn.topel@gmail.com> wrote:
>
> On Tue, 26 Nov 2019 at 14:25, Shea Levy <shea@shealevy.com> wrote:
> >
> > Hi Björn,
> >
> > Unfortunately I'm not sure what more is needed to get this in, and I'm
> > in the middle of a move and won't have easy access to my RISC-V setup
> > for testing. I don't think you can count on me for this one.
> >
>
> Thanks for getting back quickly! No worries, I'll pick it up!
>

I just pulled in your patch in my series [1] (it's not done for
submission yet, but passes all tests); Just to get the idea. Reading
up on the thread, it looks like we can share some more between the
archs (mips).


Thanks,
Björn

[1] https://github.com/bjoto/linux/tree/rv64-bpf-jit-bcc
>
> Cheers,
> Björn

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