2023-12-22 11:57:18

by Guo Ren

[permalink] [raw]
Subject: [PATCH V3 0/4] riscv: mm: Fixup & Optimize COMPAT code

From: Guo Ren <[email protected]>

When the task is in COMPAT mode, the TASK_SIZE should be 2GB, so
STACK_TOP_MAX and arch_get_mmap_end must be limited to 2 GB. This series
fixes the problem made by commit: add2cc6b6515 ("RISC-V: mm: Restrict
address space for sv39,sv48,sv57") and optimizes the related coding
convention of TASK_SIZE.

Changelog:
v3:
- Remove wrong modification of arch_get_mmap_end
- Remove is_compat_task optimization
- Update comment log

v2:
https://lore.kernel.org/linux-riscv/[email protected]/
- Separate rename from fixup
- Add STACK_TOP_MAX fixup for compat
- Add Cleanup & rename patches

v1:
https://lore.kernel.org/linux-riscv/[email protected]/

Guo Ren (4):
riscv: mm: Fixup compat mode boot failure
riscv: mm: Fixup compat arch_get_mmap_end
riscv: mm: Remove unused TASK_SIZE_MIN
riscv: mm: Optimize TASK_SIZE definition

arch/riscv/include/asm/pgtable.h | 7 +++----
arch/riscv/include/asm/processor.h | 2 +-
2 files changed, 4 insertions(+), 5 deletions(-)

--
2.40.1



2023-12-22 11:57:41

by Guo Ren

[permalink] [raw]
Subject: [PATCH V3 1/4] riscv: mm: Fixup compat mode boot failure

From: Guo Ren <[email protected]>

In COMPAT mode, the STACK_TOP is DEFAULT_MAP_WINDOW (0x80000000), but
the TASK_SIZE is 0x7fff000. When the user stack is upon 0x7fff000, it
will cause a user segment fault. Sometimes, it would cause boot
failure when the whole rootfs is rv32.

Freeing unused kernel image (initmem) memory: 2236K
Run /sbin/init as init process
Starting init: /sbin/init exists but couldn't execute it (error -14)
Run /etc/init as init process
...

Increase the TASK_SIZE to cover STACK_TOP.

Cc: [email protected]
Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57")
Signed-off-by: Guo Ren <[email protected]>
Signed-off-by: Guo Ren <[email protected]>
---
arch/riscv/include/asm/pgtable.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index ab00235b018f..74ffb2178f54 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -881,7 +881,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
#define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)

#ifdef CONFIG_COMPAT
-#define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE)
+#define TASK_SIZE_32 (_AC(0x80000000, UL))
#define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
TASK_SIZE_32 : TASK_SIZE_64)
#else
--
2.40.1


2023-12-22 11:58:45

by Guo Ren

[permalink] [raw]
Subject: [PATCH V3 2/4] riscv: mm: Fixup compat arch_get_mmap_end

From: Guo Ren <[email protected]>

When the task is in COMPAT mode, the arch_get_mmap_end should be 2GB,
not TASK_SIZE_64. The TASK_SIZE has contained is_compat_mode()
detection, so change the definition of STACK_TOP_MAX to TASK_SIZE
directly.

Cc: [email protected]
Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57")
Signed-off-by: Guo Ren <[email protected]>
Signed-off-by: Guo Ren <[email protected]>
---
arch/riscv/include/asm/processor.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index f19f861cda54..e1944ff0757a 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -16,7 +16,7 @@

#ifdef CONFIG_64BIT
#define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1))
-#define STACK_TOP_MAX TASK_SIZE_64
+#define STACK_TOP_MAX TASK_SIZE

#define arch_get_mmap_end(addr, len, flags) \
({ \
--
2.40.1


2023-12-22 11:58:56

by Guo Ren

[permalink] [raw]
Subject: [PATCH V3 3/4] riscv: mm: Remove unused TASK_SIZE_MIN

From: Guo Ren <[email protected]>

Remove TASK_SIZE_MIN because it's not used anymore.

Reviewed-by: Leonardo Bras <[email protected]>
Signed-off-by: Guo Ren <[email protected]>
Signed-off-by: Guo Ren <[email protected]>
---
arch/riscv/include/asm/pgtable.h | 2 --
1 file changed, 2 deletions(-)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 74ffb2178f54..e415582276ec 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -878,7 +878,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
*/
#ifdef CONFIG_64BIT
#define TASK_SIZE_64 (PGDIR_SIZE * PTRS_PER_PGD / 2)
-#define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)

#ifdef CONFIG_COMPAT
#define TASK_SIZE_32 (_AC(0x80000000, UL))
@@ -890,7 +889,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)

#else
#define TASK_SIZE FIXADDR_START
-#define TASK_SIZE_MIN TASK_SIZE
#endif

#else /* CONFIG_MMU */
--
2.40.1


2023-12-22 11:59:13

by Guo Ren

[permalink] [raw]
Subject: [PATCH V3 4/4] riscv: mm: Optimize TASK_SIZE definition

From: Guo Ren <[email protected]>

Unify the TASK_SIZE definition with VA_BITS for better readability.
Add COMPAT mode user address space info in the comment.

Reviewed-by: Leonardo Bras <[email protected]>
Signed-off-by: Guo Ren <[email protected]>
Signed-off-by: Guo Ren <[email protected]>
---
arch/riscv/include/asm/pgtable.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index e415582276ec..271565e1956f 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -866,6 +866,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
* Note that PGDIR_SIZE must evenly divide TASK_SIZE.
* Task size is:
* - 0x9fc00000 (~2.5GB) for RV32.
+ * - 0x80000000 ( 2GB) for RV64 compat mode
* - 0x4000000000 ( 256GB) for RV64 using SV39 mmu
* - 0x800000000000 ( 128TB) for RV64 using SV48 mmu
* - 0x100000000000000 ( 64PB) for RV64 using SV57 mmu
@@ -877,10 +878,10 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
* Similarly for SV57, bits 63–57 must be equal to bit 56.
*/
#ifdef CONFIG_64BIT
-#define TASK_SIZE_64 (PGDIR_SIZE * PTRS_PER_PGD / 2)
+#define TASK_SIZE_64 (UL(1) << (VA_BITS - 1))

#ifdef CONFIG_COMPAT
-#define TASK_SIZE_32 (_AC(0x80000000, UL))
+#define TASK_SIZE_32 (UL(1) << (VA_BITS_SV32 - 1))
#define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
TASK_SIZE_32 : TASK_SIZE_64)
#else
--
2.40.1


2023-12-23 02:52:17

by Leonardo Bras

[permalink] [raw]
Subject: Re: [PATCH V3 2/4] riscv: mm: Fixup compat arch_get_mmap_end

On Fri, Dec 22, 2023 at 06:57:01AM -0500, [email protected] wrote:
> From: Guo Ren <[email protected]>
>
> When the task is in COMPAT mode, the arch_get_mmap_end should be 2GB,
> not TASK_SIZE_64. The TASK_SIZE has contained is_compat_mode()
> detection, so change the definition of STACK_TOP_MAX to TASK_SIZE
> directly.
>
> Cc: [email protected]
> Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57")
> Signed-off-by: Guo Ren <[email protected]>
> Signed-off-by: Guo Ren <[email protected]>
> ---
> arch/riscv/include/asm/processor.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
> index f19f861cda54..e1944ff0757a 100644
> --- a/arch/riscv/include/asm/processor.h
> +++ b/arch/riscv/include/asm/processor.h
> @@ -16,7 +16,7 @@
>
> #ifdef CONFIG_64BIT
> #define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1))
> -#define STACK_TOP_MAX TASK_SIZE_64
> +#define STACK_TOP_MAX TASK_SIZE
>
> #define arch_get_mmap_end(addr, len, flags) \
> ({ \
> --
> 2.40.1
>


LGTM.

FWIW:
Reviewed-by: Leonardo Bras <[email protected]>


2023-12-23 02:59:04

by Leonardo Bras

[permalink] [raw]
Subject: Re: [PATCH V3 1/4] riscv: mm: Fixup compat mode boot failure

On Fri, Dec 22, 2023 at 06:57:00AM -0500, [email protected] wrote:
> From: Guo Ren <[email protected]>
>
> In COMPAT mode, the STACK_TOP is DEFAULT_MAP_WINDOW (0x80000000), but
> the TASK_SIZE is 0x7fff000. When the user stack is upon 0x7fff000, it
> will cause a user segment fault. Sometimes, it would cause boot
> failure when the whole rootfs is rv32.
>
> Freeing unused kernel image (initmem) memory: 2236K
> Run /sbin/init as init process
> Starting init: /sbin/init exists but couldn't execute it (error -14)
> Run /etc/init as init process
> ...
>
> Increase the TASK_SIZE to cover STACK_TOP.
>
> Cc: [email protected]
> Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57")
> Signed-off-by: Guo Ren <[email protected]>
> Signed-off-by: Guo Ren <[email protected]>
> ---
> arch/riscv/include/asm/pgtable.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index ab00235b018f..74ffb2178f54 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -881,7 +881,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> #define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
>
> #ifdef CONFIG_COMPAT
> -#define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE)
> +#define TASK_SIZE_32 (_AC(0x80000000, UL))
> #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
> TASK_SIZE_32 : TASK_SIZE_64)
> #else
> --
> 2.40.1
>

I am not really involved in the issue this is solving, so I have no
technical opinion on the solution.

IIUC there should always be (TASK_SIZE >= STACK_TOP), so by itself this
is fixing an issue.

I have reviewed the code and it does exactly as stated into the commit
message, so FWIW:
Reviewed-by: Leonardo Bras <[email protected]>


2023-12-23 03:10:52

by Guo Ren

[permalink] [raw]
Subject: Re: [PATCH V3 1/4] riscv: mm: Fixup compat mode boot failure

On Sat, Dec 23, 2023 at 10:58 AM Leonardo Bras <[email protected]> wrote:
>
> On Fri, Dec 22, 2023 at 06:57:00AM -0500, [email protected] wrote:
> > From: Guo Ren <[email protected]>
> >
> > In COMPAT mode, the STACK_TOP is DEFAULT_MAP_WINDOW (0x80000000), but
> > the TASK_SIZE is 0x7fff000. When the user stack is upon 0x7fff000, it
> > will cause a user segment fault. Sometimes, it would cause boot
> > failure when the whole rootfs is rv32.
> >
> > Freeing unused kernel image (initmem) memory: 2236K
> > Run /sbin/init as init process
> > Starting init: /sbin/init exists but couldn't execute it (error -14)
> > Run /etc/init as init process
> > ...
> >
> > Increase the TASK_SIZE to cover STACK_TOP.
> >
> > Cc: [email protected]
> > Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57")
> > Signed-off-by: Guo Ren <[email protected]>
> > Signed-off-by: Guo Ren <[email protected]>
> > ---
> > arch/riscv/include/asm/pgtable.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> > index ab00235b018f..74ffb2178f54 100644
> > --- a/arch/riscv/include/asm/pgtable.h
> > +++ b/arch/riscv/include/asm/pgtable.h
> > @@ -881,7 +881,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> > #define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
> >
> > #ifdef CONFIG_COMPAT
> > -#define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE)
> > +#define TASK_SIZE_32 (_AC(0x80000000, UL))
> > #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
> > TASK_SIZE_32 : TASK_SIZE_64)
> > #else
> > --
> > 2.40.1
> >
>
> I am not really involved in the issue this is solving, so I have no
> technical opinion on the solution.
>
> IIUC there should always be (TASK_SIZE >= STACK_TOP), so by itself this
> is fixing an issue.
>
> I have reviewed the code and it does exactly as stated into the commit
> message, so FWIW:
> Reviewed-by: Leonardo Bras <[email protected]>
Thx,

I found this problem because it can't boot my rv32 buildroot-rootfs in
v6.6. But it's okay in v6.5. So I used git bisect and found commit:
add2cc6b6515 ("RISC-V: mm: Restrict address space for
sv39,sv48,sv57"), which caused that.

Ping Charlie, I hope it can be fixed in the v6.6 long-term version.

>



--
Best Regards
Guo Ren

2023-12-23 03:36:53

by Charlie Jenkins

[permalink] [raw]
Subject: Re: [PATCH V3 1/4] riscv: mm: Fixup compat mode boot failure

On Sat, Dec 23, 2023 at 11:07:29AM +0800, Guo Ren wrote:
> On Sat, Dec 23, 2023 at 10:58 AM Leonardo Bras <[email protected]> wrote:
> >
> > On Fri, Dec 22, 2023 at 06:57:00AM -0500, [email protected] wrote:
> > > From: Guo Ren <[email protected]>
> > >
> > > In COMPAT mode, the STACK_TOP is DEFAULT_MAP_WINDOW (0x80000000), but
> > > the TASK_SIZE is 0x7fff000. When the user stack is upon 0x7fff000, it
> > > will cause a user segment fault. Sometimes, it would cause boot
> > > failure when the whole rootfs is rv32.
> > >
> > > Freeing unused kernel image (initmem) memory: 2236K
> > > Run /sbin/init as init process
> > > Starting init: /sbin/init exists but couldn't execute it (error -14)
> > > Run /etc/init as init process
> > > ...
> > >
> > > Increase the TASK_SIZE to cover STACK_TOP.
> > >
> > > Cc: [email protected]
> > > Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57")
> > > Signed-off-by: Guo Ren <[email protected]>
> > > Signed-off-by: Guo Ren <[email protected]>
> > > ---
> > > arch/riscv/include/asm/pgtable.h | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> > > index ab00235b018f..74ffb2178f54 100644
> > > --- a/arch/riscv/include/asm/pgtable.h
> > > +++ b/arch/riscv/include/asm/pgtable.h
> > > @@ -881,7 +881,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> > > #define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
> > >
> > > #ifdef CONFIG_COMPAT
> > > -#define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE)
> > > +#define TASK_SIZE_32 (_AC(0x80000000, UL))
> > > #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
> > > TASK_SIZE_32 : TASK_SIZE_64)
> > > #else
> > > --
> > > 2.40.1
> > >
> >
> > I am not really involved in the issue this is solving, so I have no
> > technical opinion on the solution.
> >
> > IIUC there should always be (TASK_SIZE >= STACK_TOP), so by itself this
> > is fixing an issue.
> >
> > I have reviewed the code and it does exactly as stated into the commit
> > message, so FWIW:
> > Reviewed-by: Leonardo Bras <[email protected]>
> Thx,
>
> I found this problem because it can't boot my rv32 buildroot-rootfs in
> v6.6. But it's okay in v6.5. So I used git bisect and found commit:
> add2cc6b6515 ("RISC-V: mm: Restrict address space for
> sv39,sv48,sv57"), which caused that.
>
> Ping Charlie, I hope it can be fixed in the v6.6 long-term version.

I have looked at this more I do agree that this change makes sense. I
was thinking that it was valid to have STACK_TOP that was greater than
TASK_SIZE but I am no longer convinced that is true. Thank you for
looking into this.

Reviewed-by: Charlie Jenkins <[email protected]>

>
> >
>
>
>
> --
> Best Regards
> Guo Ren

2023-12-23 03:40:11

by Charlie Jenkins

[permalink] [raw]
Subject: Re: [PATCH V3 2/4] riscv: mm: Fixup compat arch_get_mmap_end

On Fri, Dec 22, 2023 at 11:51:48PM -0300, Leonardo Bras wrote:
> On Fri, Dec 22, 2023 at 06:57:01AM -0500, [email protected] wrote:
> > From: Guo Ren <[email protected]>
> >
> > When the task is in COMPAT mode, the arch_get_mmap_end should be 2GB,
> > not TASK_SIZE_64. The TASK_SIZE has contained is_compat_mode()
> > detection, so change the definition of STACK_TOP_MAX to TASK_SIZE
> > directly.
> >
> > Cc: [email protected]
> > Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57")
> > Signed-off-by: Guo Ren <[email protected]>
> > Signed-off-by: Guo Ren <[email protected]>
> > ---
> > arch/riscv/include/asm/processor.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
> > index f19f861cda54..e1944ff0757a 100644
> > --- a/arch/riscv/include/asm/processor.h
> > +++ b/arch/riscv/include/asm/processor.h
> > @@ -16,7 +16,7 @@
> >
> > #ifdef CONFIG_64BIT
> > #define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1))
> > -#define STACK_TOP_MAX TASK_SIZE_64
> > +#define STACK_TOP_MAX TASK_SIZE
> >
> > #define arch_get_mmap_end(addr, len, flags) \
> > ({ \
> > --
> > 2.40.1
> >
>
>
> LGTM.
>
> FWIW:
> Reviewed-by: Leonardo Bras <[email protected]>

Reviewed-by: Charlie Jenkins <[email protected]>

>

Subject: Re: [PATCH V3 0/4] riscv: mm: Fixup & Optimize COMPAT code

Hello:

This series was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <[email protected]>:

On Fri, 22 Dec 2023 06:56:59 -0500 you wrote:
> From: Guo Ren <[email protected]>
>
> When the task is in COMPAT mode, the TASK_SIZE should be 2GB, so
> STACK_TOP_MAX and arch_get_mmap_end must be limited to 2 GB. This series
> fixes the problem made by commit: add2cc6b6515 ("RISC-V: mm: Restrict
> address space for sv39,sv48,sv57") and optimizes the related coding
> convention of TASK_SIZE.
>
> [...]

Here is the summary with links:
- [V3,1/4] riscv: mm: Fixup compat mode boot failure
https://git.kernel.org/riscv/c/5f449e245e5b
- [V3,2/4] riscv: mm: Fixup compat arch_get_mmap_end
https://git.kernel.org/riscv/c/97b7ac69be2e
- [V3,3/4] riscv: mm: Remove unused TASK_SIZE_MIN
(no matching commit)
- [V3,4/4] riscv: mm: Optimize TASK_SIZE definition
(no matching commit)

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



2024-01-24 18:36:39

by Charlie Jenkins

[permalink] [raw]
Subject: Re: [PATCH V3 3/4] riscv: mm: Remove unused TASK_SIZE_MIN

On Fri, Dec 22, 2023 at 06:57:02AM -0500, [email protected] wrote:
> From: Guo Ren <[email protected]>
>
> Remove TASK_SIZE_MIN because it's not used anymore.
>
> Reviewed-by: Leonardo Bras <[email protected]>
> Signed-off-by: Guo Ren <[email protected]>
> Signed-off-by: Guo Ren <[email protected]>
> ---
> arch/riscv/include/asm/pgtable.h | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 74ffb2178f54..e415582276ec 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -878,7 +878,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> */
> #ifdef CONFIG_64BIT
> #define TASK_SIZE_64 (PGDIR_SIZE * PTRS_PER_PGD / 2)
> -#define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
>
> #ifdef CONFIG_COMPAT
> #define TASK_SIZE_32 (_AC(0x80000000, UL))
> @@ -890,7 +889,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
>
> #else
> #define TASK_SIZE FIXADDR_START
> -#define TASK_SIZE_MIN TASK_SIZE
> #endif
>
> #else /* CONFIG_MMU */
> --
> 2.40.1
>

Reviewed-by: Charlie Jenkins <[email protected]>


2024-01-24 18:36:53

by Charlie Jenkins

[permalink] [raw]
Subject: Re: [PATCH V3 4/4] riscv: mm: Optimize TASK_SIZE definition

On Fri, Dec 22, 2023 at 06:57:03AM -0500, [email protected] wrote:
> From: Guo Ren <[email protected]>
>
> Unify the TASK_SIZE definition with VA_BITS for better readability.
> Add COMPAT mode user address space info in the comment.
>
> Reviewed-by: Leonardo Bras <[email protected]>
> Signed-off-by: Guo Ren <[email protected]>
> Signed-off-by: Guo Ren <[email protected]>
> ---
> arch/riscv/include/asm/pgtable.h | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index e415582276ec..271565e1956f 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -866,6 +866,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> * Note that PGDIR_SIZE must evenly divide TASK_SIZE.
> * Task size is:
> * - 0x9fc00000 (~2.5GB) for RV32.
> + * - 0x80000000 ( 2GB) for RV64 compat mode
> * - 0x4000000000 ( 256GB) for RV64 using SV39 mmu
> * - 0x800000000000 ( 128TB) for RV64 using SV48 mmu
> * - 0x100000000000000 ( 64PB) for RV64 using SV57 mmu
> @@ -877,10 +878,10 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> * Similarly for SV57, bits 63–57 must be equal to bit 56.
> */
> #ifdef CONFIG_64BIT
> -#define TASK_SIZE_64 (PGDIR_SIZE * PTRS_PER_PGD / 2)
> +#define TASK_SIZE_64 (UL(1) << (VA_BITS - 1))
>
> #ifdef CONFIG_COMPAT
> -#define TASK_SIZE_32 (_AC(0x80000000, UL))
> +#define TASK_SIZE_32 (UL(1) << (VA_BITS_SV32 - 1))
> #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
> TASK_SIZE_32 : TASK_SIZE_64)
> #else
> --
> 2.40.1
>

Reviewed-by: Charlie Jenkins <[email protected]>