* [RFC PATCH 1/1] riscv: Improve arch_get_mmap_end() macro
@ 2023-12-22 8:27 Leonardo Bras
2023-12-22 11:48 ` Guo Ren
0 siblings, 1 reply; 3+ messages in thread
From: Leonardo Bras @ 2023-12-22 8:27 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Björn Töpel,
Conor Dooley, Vincent Chen, Andy Chiu, Leonardo Bras,
Charlie Jenkins, Clément Léger, Guo Ren
Cc: linux-riscv, linux-kernel
This macro caused me some confusion, which took some reviewer's time to
make it clear, so I propose adding a short comment in code to avoid
confusion in the future.
Also, added some improvements to the macro, such as removing the
assumption of VA_USER_SV57 being the largest address space.
Signed-off-by: Leonardo Bras <leobras@redhat.com>
---
arch/riscv/include/asm/processor.h | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index f19f861cda549..2278e2a8362af 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -18,15 +18,21 @@
#define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1))
#define STACK_TOP_MAX TASK_SIZE_64
+/*
+ * addr is a hint to the maximum userspace address that mmap should provide, so
+ * this macro needs to return the largest address space available so that
+ * mmap_end < addr, being mmap_end the top of that address space.
+ * See Documentation/arch/riscv/vm-layout.rst for more details.
+ */
#define arch_get_mmap_end(addr, len, flags) \
({ \
unsigned long mmap_end; \
typeof(addr) _addr = (addr); \
if ((_addr) == 0 || (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())) \
mmap_end = STACK_TOP_MAX; \
- else if ((_addr) >= VA_USER_SV57) \
- mmap_end = STACK_TOP_MAX; \
- else if ((((_addr) >= VA_USER_SV48)) && (VA_BITS >= VA_BITS_SV48)) \
+ else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \
+ mmap_end = VA_USER_SV57; \
+ else if (((_addr) >= VA_USER_SV48) && (VA_BITS >= VA_BITS_SV48)) \
mmap_end = VA_USER_SV48; \
else \
mmap_end = VA_USER_SV39; \
--
2.43.0
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RFC PATCH 1/1] riscv: Improve arch_get_mmap_end() macro
2023-12-22 8:27 [RFC PATCH 1/1] riscv: Improve arch_get_mmap_end() macro Leonardo Bras
@ 2023-12-22 11:48 ` Guo Ren
2023-12-22 17:15 ` Leonardo Bras
0 siblings, 1 reply; 3+ messages in thread
From: Guo Ren @ 2023-12-22 11:48 UTC (permalink / raw)
To: Leonardo Bras
Cc: Paul Walmsley, Palmer Dabbelt, Albert Ou, Björn Töpel,
Conor Dooley, Vincent Chen, Andy Chiu, Charlie Jenkins,
Clément Léger, linux-riscv, linux-kernel
On Fri, Dec 22, 2023 at 4:27 PM Leonardo Bras <leobras@redhat.com> wrote:
>
> This macro caused me some confusion, which took some reviewer's time to
> make it clear, so I propose adding a short comment in code to avoid
> confusion in the future.
>
> Also, added some improvements to the macro, such as removing the
> assumption of VA_USER_SV57 being the largest address space.
>
> Signed-off-by: Leonardo Bras <leobras@redhat.com>
> ---
> arch/riscv/include/asm/processor.h | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
> index f19f861cda549..2278e2a8362af 100644
> --- a/arch/riscv/include/asm/processor.h
> +++ b/arch/riscv/include/asm/processor.h
> @@ -18,15 +18,21 @@
> #define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1))
> #define STACK_TOP_MAX TASK_SIZE_64
>
> +/*
> + * addr is a hint to the maximum userspace address that mmap should provide, so
> + * this macro needs to return the largest address space available so that
> + * mmap_end < addr, being mmap_end the top of that address space.
> + * See Documentation/arch/riscv/vm-layout.rst for more details.
> + */
> #define arch_get_mmap_end(addr, len, flags) \
> ({ \
> unsigned long mmap_end; \
> typeof(addr) _addr = (addr); \
> if ((_addr) == 0 || (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())) \
> mmap_end = STACK_TOP_MAX; \
> - else if ((_addr) >= VA_USER_SV57) \
> - mmap_end = STACK_TOP_MAX; \
> - else if ((((_addr) >= VA_USER_SV48)) && (VA_BITS >= VA_BITS_SV48)) \
> + else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \
> + mmap_end = VA_USER_SV57; \
It's clearer.
LGTM.
Reviewed-by: Guo Ren <guoren@kernel.org>
> + else if (((_addr) >= VA_USER_SV48) && (VA_BITS >= VA_BITS_SV48)) \
> mmap_end = VA_USER_SV48; \
> else \
> mmap_end = VA_USER_SV39; \
> --
> 2.43.0
>
--
Best Regards
Guo Ren
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linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC PATCH 1/1] riscv: Improve arch_get_mmap_end() macro
2023-12-22 11:48 ` Guo Ren
@ 2023-12-22 17:15 ` Leonardo Bras
0 siblings, 0 replies; 3+ messages in thread
From: Leonardo Bras @ 2023-12-22 17:15 UTC (permalink / raw)
To: Guo Ren
Cc: Leonardo Bras, Paul Walmsley, Palmer Dabbelt, Albert Ou,
Björn Töpel, Conor Dooley, Vincent Chen, Andy Chiu,
Charlie Jenkins, Clément Léger, linux-riscv,
linux-kernel
On Fri, Dec 22, 2023 at 07:48:36PM +0800, Guo Ren wrote:
> On Fri, Dec 22, 2023 at 4:27 PM Leonardo Bras <leobras@redhat.com> wrote:
> >
> > This macro caused me some confusion, which took some reviewer's time to
> > make it clear, so I propose adding a short comment in code to avoid
> > confusion in the future.
> >
> > Also, added some improvements to the macro, such as removing the
> > assumption of VA_USER_SV57 being the largest address space.
> >
> > Signed-off-by: Leonardo Bras <leobras@redhat.com>
> > ---
> > arch/riscv/include/asm/processor.h | 12 +++++++++---
> > 1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
> > index f19f861cda549..2278e2a8362af 100644
> > --- a/arch/riscv/include/asm/processor.h
> > +++ b/arch/riscv/include/asm/processor.h
> > @@ -18,15 +18,21 @@
> > #define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1))
> > #define STACK_TOP_MAX TASK_SIZE_64
> >
> > +/*
> > + * addr is a hint to the maximum userspace address that mmap should provide, so
> > + * this macro needs to return the largest address space available so that
> > + * mmap_end < addr, being mmap_end the top of that address space.
> > + * See Documentation/arch/riscv/vm-layout.rst for more details.
> > + */
> > #define arch_get_mmap_end(addr, len, flags) \
> > ({ \
> > unsigned long mmap_end; \
> > typeof(addr) _addr = (addr); \
> > if ((_addr) == 0 || (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())) \
> > mmap_end = STACK_TOP_MAX; \
> > - else if ((_addr) >= VA_USER_SV57) \
> > - mmap_end = STACK_TOP_MAX; \
> > - else if ((((_addr) >= VA_USER_SV48)) && (VA_BITS >= VA_BITS_SV48)) \
> > + else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \
> > + mmap_end = VA_USER_SV57; \
> It's clearer.
>
> LGTM.
> Reviewed-by: Guo Ren <guoren@kernel.org>
Thanks!
Leo
>
> > + else if (((_addr) >= VA_USER_SV48) && (VA_BITS >= VA_BITS_SV48)) \
> > mmap_end = VA_USER_SV48; \
> > else \
> > mmap_end = VA_USER_SV39; \
> > --
> > 2.43.0
> >
>
>
> --
> Best Regards
> Guo Ren
>
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2023-12-22 8:27 [RFC PATCH 1/1] riscv: Improve arch_get_mmap_end() macro Leonardo Bras
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