From: Mike Rapoport <rppt@kernel.org>
To: Song Liu <song@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org,
Alexandre Ghiti <alexghiti@rivosinc.com>,
Andrew Morton <akpm@linux-foundation.org>,
Bjorn Topel <bjorn@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
"David S. Miller" <davem@davemloft.net>,
Dinh Nguyen <dinguyen@kernel.org>,
Donald Dutile <ddutile@redhat.com>,
Eric Chanudet <echanude@redhat.com>,
Heiko Carstens <hca@linux.ibm.com>, Helge Deller <deller@gmx.de>,
Huacai Chen <chenhuacai@kernel.org>,
Kent Overstreet <kent.overstreet@linux.dev>,
Luis Chamberlain <mcgrof@kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Nadav Amit <nadav.amit@gmail.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Puranjay Mohan <puranjay12@gmail.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Russell King <linux@armlinux.org.uk>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
bpf@vger.kernel.org, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,
linux-mm@kvack.org, linux-modules@vger.kernel.org,
linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev,
netdev@vger.kernel.org, sparclinux@vger.kernel.org,
x86@kernel.org
Subject: Re: [PATCH v4 05/15] mm: introduce execmem_alloc() and execmem_free()
Date: Fri, 19 Apr 2024 20:02:17 +0300 [thread overview]
Message-ID: <ZiKjmaDgz_56ovbv@kernel.org> (raw)
In-Reply-To: <CAPhsuW7WoU+a46FhqqH8f-3=ehxeD4wSgKDWegMin1pT49OSWw@mail.gmail.com>
On Fri, Apr 19, 2024 at 08:54:40AM -0700, Song Liu wrote:
> On Thu, Apr 18, 2024 at 11:56 PM Mike Rapoport <rppt@kernel.org> wrote:
> >
> > On Thu, Apr 18, 2024 at 02:01:22PM -0700, Song Liu wrote:
> > > On Thu, Apr 18, 2024 at 10:54 AM Mike Rapoport <rppt@kernel.org> wrote:
> > > >
> > > > On Thu, Apr 18, 2024 at 09:13:27AM -0700, Song Liu wrote:
> > > > > On Thu, Apr 18, 2024 at 8:37 AM Mike Rapoport <rppt@kernel.org> wrote:
> > > > > > > >
> > > > > > > > I'm looking at execmem_types more as definition of the consumers, maybe I
> > > > > > > > should have named the enum execmem_consumer at the first place.
> > > > > > >
> > > > > > > I think looking at execmem_type from consumers' point of view adds
> > > > > > > unnecessary complexity. IIUC, for most (if not all) archs, ftrace, kprobe,
> > > > > > > and bpf (and maybe also module text) all have the same requirements.
> > > > > > > Did I miss something?
> > > > > >
> > > > > > It's enough to have one architecture with different constrains for kprobes
> > > > > > and bpf to warrant a type for each.
> > > > >
> > > > > AFAICT, some of these constraints can be changed without too much work.
> > > >
> > > > But why?
> > > > I honestly don't understand what are you trying to optimize here. A few
> > > > lines of initialization in execmem_info?
> > >
> > > IIUC, having separate EXECMEM_BPF and EXECMEM_KPROBE makes it
> > > harder for bpf and kprobe to share the same ROX page. In many use cases,
> > > a 2MiB page (assuming x86_64) is enough for all BPF, kprobe, ftrace, and
> > > module text. It is not efficient if we have to allocate separate pages for each
> > > of these use cases. If this is not a problem, the current approach works.
> >
> > The caching of large ROX pages does not need to be per type.
> >
> > In the POC I've posted for caching of large ROX pages on x86 [1], the cache is
> > global and to make kprobes and bpf use it it's enough to set a flag in
> > execmem_info.
> >
> > [1] https://lore.kernel.org/all/20240411160526.2093408-1-rppt@kernel.org
>
> For the ROX to work, we need different users (module text, kprobe, etc.) to have
> the same execmem_range. From [1]:
>
> static void *execmem_cache_alloc(struct execmem_range *range, size_t size)
> {
> ...
> p = __execmem_cache_alloc(size);
> if (p)
> return p;
> err = execmem_cache_populate(range, size);
> ...
> }
>
> We are calling __execmem_cache_alloc() without range. For this to work,
> we can only call execmem_cache_alloc() with one execmem_range.
Actually, on x86 this will "just work" because everything shares the same
address space :)
The 2M pages in the cache will be in the modules space, so
__execmem_cache_alloc() will always return memory from that address space.
For other architectures this indeed needs to be fixed with passing the
range to __execmem_cache_alloc() and limiting search in the cache for that
range.
> Did I miss something?
>
> Thanks,
> Song
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2024-04-19 17:03 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-11 16:00 [PATCH v4 00/15] mm: jit/text allocator Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 01/15] arm64: module: remove uneeded call to kasan_alloc_module_shadow() Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 02/15] mips: module: rename MODULE_START to MODULES_VADDR Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 03/15] nios2: define virtual address space for modules Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 04/15] module: make module_memory_{alloc,free} more self-contained Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 05/15] mm: introduce execmem_alloc() and execmem_free() Mike Rapoport
2024-04-11 19:42 ` Luis Chamberlain
2024-04-14 6:53 ` Mike Rapoport
2024-04-12 9:16 ` Ingo Molnar
2024-04-14 6:54 ` Mike Rapoport
2024-04-15 7:52 ` Peter Zijlstra
2024-04-15 16:51 ` Mike Rapoport
2024-04-15 17:36 ` Mark Rutland
2024-04-16 7:22 ` Mike Rapoport
2024-04-17 23:32 ` Song Liu
2024-04-18 15:35 ` Mike Rapoport
2024-04-18 16:13 ` Song Liu
2024-04-18 17:52 ` Mike Rapoport
2024-04-18 21:01 ` Song Liu
2024-04-19 6:55 ` Mike Rapoport
2024-04-19 15:54 ` Song Liu
2024-04-19 17:02 ` Mike Rapoport [this message]
2024-04-19 17:32 ` Song Liu
2024-04-19 19:59 ` Mike Rapoport
2024-04-19 21:42 ` Song Liu
2024-04-20 4:22 ` Mike Rapoport
2024-04-20 9:11 ` Masami Hiramatsu
2024-04-22 18:32 ` Song Liu
2024-04-17 21:06 ` Masami Hiramatsu
2024-04-11 16:00 ` [PATCH v4 06/15] mm/execmem, arch: convert simple overrides of module_alloc to execmem Mike Rapoport
2024-04-11 20:53 ` Sam Ravnborg
2024-04-14 7:26 ` Mike Rapoport
2024-04-15 8:03 ` Peter Zijlstra
2024-04-11 16:00 ` [PATCH v4 07/15] mm/execmem, arch: convert remaining " Mike Rapoport
2024-04-15 9:36 ` Peter Zijlstra
2024-04-11 16:00 ` [PATCH v4 08/15] arm64: extend execmem_info for generated code allocations Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 09/15] riscv: extend execmem_params " Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 10/15] powerpc: extend execmem_params for kprobes allocations Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 11/15] arch: make execmem setup available regardless of CONFIG_MODULES Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 12/15] x86/ftrace: enable dynamic ftrace without CONFIG_MODULES Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 13/15] powerpc: use CONFIG_EXECMEM instead of CONFIG_MODULES where appropiate Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 14/15] kprobes: remove dependency on CONFIG_MODULES Mike Rapoport
2024-04-17 21:16 ` Masami Hiramatsu
2024-04-18 15:37 ` Mike Rapoport
2024-04-19 15:49 ` Mike Rapoport
2024-04-19 15:59 ` Christophe Leroy
2024-04-20 7:33 ` Mike Rapoport
2024-04-20 9:15 ` Masami Hiramatsu
2024-04-20 10:52 ` Mike Rapoport
2024-04-11 16:00 ` [PATCH v4 15/15] bpf: remove CONFIG_BPF_JIT dependency on CONFIG_MODULES of Mike Rapoport
2024-04-11 18:00 ` [PATCH v4 00/15] mm: jit/text allocator Kent Overstreet
2024-04-11 19:45 ` Luis Chamberlain
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZiKjmaDgz_56ovbv@kernel.org \
--to=rppt@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=alexghiti@rivosinc.com \
--cc=bjorn@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=catalin.marinas@arm.com \
--cc=chenhuacai@kernel.org \
--cc=christophe.leroy@csgroup.eu \
--cc=davem@davemloft.net \
--cc=ddutile@redhat.com \
--cc=deller@gmx.de \
--cc=dinguyen@kernel.org \
--cc=echanude@redhat.com \
--cc=hca@linux.ibm.com \
--cc=kent.overstreet@linux.dev \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-modules@vger.kernel.org \
--cc=linux-parisc@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=linux-s390@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=linux@armlinux.org.uk \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=loongarch@lists.linux.dev \
--cc=mark.rutland@arm.com \
--cc=mcgrof@kernel.org \
--cc=mpe@ellerman.id.au \
--cc=nadav.amit@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=palmer@dabbelt.com \
--cc=peterz@infradead.org \
--cc=puranjay12@gmail.com \
--cc=rick.p.edgecombe@intel.com \
--cc=rostedt@goodmis.org \
--cc=song@kernel.org \
--cc=sparclinux@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=tsbogend@alpha.franken.de \
--cc=will@kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).