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From: Jisheng Zhang <jszhang@kernel.org>
To: Palmer Dabbelt <palmer@dabbelt.com>
Cc: anup@brainfault.org, Paul Walmsley <paul.walmsley@sifive.com>,
	aou@eecs.berkeley.edu, ryabinin.a.a@gmail.com, glider@google.com,
	andreyknvl@gmail.com, dvyukov@google.com,
	vincenzo.frascino@arm.com, alexandre.ghiti@canonical.com,
	Atish Patra <atishp@rivosinc.com>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	kasan-dev@googlegroups.com
Subject: Re: [PATCH v4 0/2] use static key to optimize pgtable_l4_enabled
Date: Fri, 15 Jul 2022 21:35:43 +0800	[thread overview]
Message-ID: <YtFtL3+/3FNkalZ5@xhacker> (raw)
In-Reply-To: <mhng-17913c13-57bd-42f9-9136-b4eb9632253c@palmer-mbp2014>

On Fri, Jul 01, 2022 at 08:48:25PM -0700, Palmer Dabbelt wrote:
> On Sat, 25 Jun 2022 21:33:07 PDT (-0700), anup@brainfault.org wrote:
> > On Sat, May 21, 2022 at 8:13 PM Jisheng Zhang <jszhang@kernel.org> wrote:
> > > 
> > > The pgtable_l4|[l5]_enabled check sits at hot code path, performance
> > > is impacted a lot. Since pgtable_l4|[l5]_enabled isn't changed after
> > > boot, so static key can be used to solve the performance issue[1].
> > > 
> > > An unified way static key was introduced in [2], but it only targets
> > > riscv isa extension. We dunno whether SV48 and SV57 will be considered
> > > as isa extension, so the unified solution isn't used for
> > > pgtable_l4[l5]_enabled now.
> > > 
> > > patch1 fixes a NULL pointer deference if static key is used a bit earlier.
> > > patch2 uses the static key to optimize pgtable_l4|[l5]_enabled.
> > > 
> > > [1] http://lists.infradead.org/pipermail/linux-riscv/2021-December/011164.html
> > > [2] https://lore.kernel.org/linux-riscv/20220517184453.3558-1-jszhang@kernel.org/T/#t
> > > 
> > > Since v3:
> > >  - fix W=1 call to undeclared function 'static_branch_likely' error
> > > 
> > > Since v2:
> > >  - move the W=1 warning fix to a separate patch
> > >  - move the unified way to use static key to a new patch series.
> > > 
> > > Since v1:
> > >  - Add a W=1 warning fix
> > >  - Fix W=1 error
> > >  - Based on v5.18-rcN, since SV57 support is added, so convert
> > >    pgtable_l5_enabled as well.
> > > 
> > > 
> > > 
> > > Jisheng Zhang (2):
> > >   riscv: move sbi_init() earlier before jump_label_init()
> > >   riscv: turn pgtable_l4|[l5]_enabled to static key for RV64
> > 
> > I have tested both these patches on QEMU RV64 and RV32.
> > 
> > Tested-by: Anup Patel <anup@brainfault.org>
> > 
> > Thanks,
> > Anup
> 
> Thanks for testing these.  Unfortunatly they're failing for me under my
> kasan+sparsemem-vmemmap config, which looks like a defconfig with
> 
>    CONFIG_KASAN=y
>    # CONFIG_FLATMEM_MANUAL is not set
>    CONFIG_SPARSEMEM_MANUAL=y
>    CONFIG_SPARSEMEM=y
>    # CONFIG_SPARSEMEM_VMEMMAP is not set

Hi Palmer,

Thank you for the hint, I find the reason: SPARSEMEM is the key, KASAN
doesn't matter. To fix this issue, we need to move
riscv_finalise_pgtable_lx() after sparse_init(). I will send out a
newer version soon.

> 
> Nothing's really jumping out and I'm not sure that's a super compelling
> configuration, but IIRC it's found a handful of issues before so I'm not
> sure it's sane to just toss it.
> 
> I've put this all on the riscv-pgtable_static_key branch of
> kernel.org/palmer/linux .  If nobody has the time to look then I'll try and
> give it another shot, but I'm pretty buried right now so happy to have the
> help.

Let me know if you want a seperate patch against
riscv-pgtable_static_key branch.

Thanks

> 
> > 
> > > 
> > >  arch/riscv/include/asm/pgalloc.h    | 16 ++++----
> > >  arch/riscv/include/asm/pgtable-32.h |  3 ++
> > >  arch/riscv/include/asm/pgtable-64.h | 60 ++++++++++++++++++---------
> > >  arch/riscv/include/asm/pgtable.h    |  5 +--
> > >  arch/riscv/kernel/cpu.c             |  4 +-
> > >  arch/riscv/kernel/setup.c           |  2 +-
> > >  arch/riscv/mm/init.c                | 64 ++++++++++++++++++-----------
> > >  arch/riscv/mm/kasan_init.c          | 16 ++++----
> > >  8 files changed, 104 insertions(+), 66 deletions(-)
> > > 
> > > --
> > > 2.34.1
> > > 

WARNING: multiple messages have this Message-ID
From: Jisheng Zhang <jszhang@kernel.org>
To: Palmer Dabbelt <palmer@dabbelt.com>
Cc: anup@brainfault.org, Paul Walmsley <paul.walmsley@sifive.com>,
	aou@eecs.berkeley.edu, ryabinin.a.a@gmail.com, glider@google.com,
	andreyknvl@gmail.com, dvyukov@google.com,
	vincenzo.frascino@arm.com, alexandre.ghiti@canonical.com,
	Atish Patra <atishp@rivosinc.com>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	kasan-dev@googlegroups.com
Subject: Re: [PATCH v4 0/2] use static key to optimize pgtable_l4_enabled
Date: Fri, 15 Jul 2022 21:35:43 +0800	[thread overview]
Message-ID: <YtFtL3+/3FNkalZ5@xhacker> (raw)
In-Reply-To: <mhng-17913c13-57bd-42f9-9136-b4eb9632253c@palmer-mbp2014>

On Fri, Jul 01, 2022 at 08:48:25PM -0700, Palmer Dabbelt wrote:
> On Sat, 25 Jun 2022 21:33:07 PDT (-0700), anup@brainfault.org wrote:
> > On Sat, May 21, 2022 at 8:13 PM Jisheng Zhang <jszhang@kernel.org> wrote:
> > > 
> > > The pgtable_l4|[l5]_enabled check sits at hot code path, performance
> > > is impacted a lot. Since pgtable_l4|[l5]_enabled isn't changed after
> > > boot, so static key can be used to solve the performance issue[1].
> > > 
> > > An unified way static key was introduced in [2], but it only targets
> > > riscv isa extension. We dunno whether SV48 and SV57 will be considered
> > > as isa extension, so the unified solution isn't used for
> > > pgtable_l4[l5]_enabled now.
> > > 
> > > patch1 fixes a NULL pointer deference if static key is used a bit earlier.
> > > patch2 uses the static key to optimize pgtable_l4|[l5]_enabled.
> > > 
> > > [1] http://lists.infradead.org/pipermail/linux-riscv/2021-December/011164.html
> > > [2] https://lore.kernel.org/linux-riscv/20220517184453.3558-1-jszhang@kernel.org/T/#t
> > > 
> > > Since v3:
> > >  - fix W=1 call to undeclared function 'static_branch_likely' error
> > > 
> > > Since v2:
> > >  - move the W=1 warning fix to a separate patch
> > >  - move the unified way to use static key to a new patch series.
> > > 
> > > Since v1:
> > >  - Add a W=1 warning fix
> > >  - Fix W=1 error
> > >  - Based on v5.18-rcN, since SV57 support is added, so convert
> > >    pgtable_l5_enabled as well.
> > > 
> > > 
> > > 
> > > Jisheng Zhang (2):
> > >   riscv: move sbi_init() earlier before jump_label_init()
> > >   riscv: turn pgtable_l4|[l5]_enabled to static key for RV64
> > 
> > I have tested both these patches on QEMU RV64 and RV32.
> > 
> > Tested-by: Anup Patel <anup@brainfault.org>
> > 
> > Thanks,
> > Anup
> 
> Thanks for testing these.  Unfortunatly they're failing for me under my
> kasan+sparsemem-vmemmap config, which looks like a defconfig with
> 
>    CONFIG_KASAN=y
>    # CONFIG_FLATMEM_MANUAL is not set
>    CONFIG_SPARSEMEM_MANUAL=y
>    CONFIG_SPARSEMEM=y
>    # CONFIG_SPARSEMEM_VMEMMAP is not set

Hi Palmer,

Thank you for the hint, I find the reason: SPARSEMEM is the key, KASAN
doesn't matter. To fix this issue, we need to move
riscv_finalise_pgtable_lx() after sparse_init(). I will send out a
newer version soon.

> 
> Nothing's really jumping out and I'm not sure that's a super compelling
> configuration, but IIRC it's found a handful of issues before so I'm not
> sure it's sane to just toss it.
> 
> I've put this all on the riscv-pgtable_static_key branch of
> kernel.org/palmer/linux .  If nobody has the time to look then I'll try and
> give it another shot, but I'm pretty buried right now so happy to have the
> help.

Let me know if you want a seperate patch against
riscv-pgtable_static_key branch.

Thanks

> 
> > 
> > > 
> > >  arch/riscv/include/asm/pgalloc.h    | 16 ++++----
> > >  arch/riscv/include/asm/pgtable-32.h |  3 ++
> > >  arch/riscv/include/asm/pgtable-64.h | 60 ++++++++++++++++++---------
> > >  arch/riscv/include/asm/pgtable.h    |  5 +--
> > >  arch/riscv/kernel/cpu.c             |  4 +-
> > >  arch/riscv/kernel/setup.c           |  2 +-
> > >  arch/riscv/mm/init.c                | 64 ++++++++++++++++++-----------
> > >  arch/riscv/mm/kasan_init.c          | 16 ++++----
> > >  8 files changed, 104 insertions(+), 66 deletions(-)
> > > 
> > > --
> > > 2.34.1
> > > 

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  reply	other threads:[~2022-07-15 13:44 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-21 14:34 [PATCH v4 0/2] use static key to optimize pgtable_l4_enabled Jisheng Zhang
2022-05-21 14:34 ` Jisheng Zhang
2022-05-21 14:34 ` [PATCH v4 1/2] riscv: move sbi_init() earlier before jump_label_init() Jisheng Zhang
2022-05-21 14:34   ` Jisheng Zhang
2022-05-22  8:01   ` Atish Patra
2022-05-22  8:01     ` Atish Patra
2022-06-26  4:32   ` Anup Patel
2022-06-26  4:32     ` Anup Patel
2022-06-27  6:47     ` Atish Patra
2022-06-27  6:47       ` Atish Patra
2022-05-21 14:34 ` [PATCH v4 2/2] riscv: turn pgtable_l4|[l5]_enabled to static key for RV64 Jisheng Zhang
2022-05-21 14:34   ` Jisheng Zhang
2022-05-24 15:59   ` Anup Patel
2022-05-24 15:59     ` Anup Patel
2022-06-05  6:12     ` Jisheng Zhang
2022-06-05  6:12       ` Jisheng Zhang
2022-06-26  4:33 ` [PATCH v4 0/2] use static key to optimize pgtable_l4_enabled Anup Patel
2022-06-26  4:33   ` Anup Patel
2022-07-02  3:48   ` Palmer Dabbelt
2022-07-02  3:48     ` Palmer Dabbelt
2022-07-15 13:35     ` Jisheng Zhang [this message]
2022-07-15 13:35       ` Jisheng Zhang

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