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From: Will Deacon <will@kernel.org>
To: Klara Modin <klarasmodin@gmail.com>
Cc: "Mike Rapoport" <rppt@kernel.org>,
	linux-kernel@vger.kernel.org,
	"Alexandre Ghiti" <alexghiti@rivosinc.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Björn Töpel" <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>,
	"Liviu Dudau" <liviu@dudau.co.uk>,
	"Luis Chamberlain" <mcgrof@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Masami Hiramatsu" <mhiramat@kernel.org>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Nadav Amit" <nadav.amit@gmail.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Philippe Mathieu-Daudé" <philmd@linaro.org>,
	"Rick Edgecombe" <rick.p.edgecombe@intel.com>,
	"Russell King" <linux@armlinux.org.uk>,
	"Sam Ravnborg" <sam@ravnborg.org>, "Song Liu" <song@kernel.org>,
	"Steven Rostedt" <rostedt@goodmis.org>,
	"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	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 RESEND v8 16/16] bpf: remove CONFIG_BPF_JIT dependency on CONFIG_MODULES of
Date: Fri, 17 May 2024 16:46:32 +0100	[thread overview]
Message-ID: <20240517154632.GA320@willie-the-truck> (raw)
In-Reply-To: <7983fbbf-0127-457c-9394-8d6e4299c685@gmail.com>

Hi Klara,

On Fri, May 17, 2024 at 01:00:31AM +0200, Klara Modin wrote:
> On 2024-05-05 18:06, Mike Rapoport wrote:
> > From: "Mike Rapoport (IBM)" <rppt@kernel.org>
> > 
> > BPF just-in-time compiler depended on CONFIG_MODULES because it used
> > module_alloc() to allocate memory for the generated code.
> > 
> > Since code allocations are now implemented with execmem, drop dependency of
> > CONFIG_BPF_JIT on CONFIG_MODULES and make it select CONFIG_EXECMEM.
> > 
> > Suggested-by: Björn Töpel <bjorn@kernel.org>
> > Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
> > ---
> >   kernel/bpf/Kconfig | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
> > index bc25f5098a25..f999e4e0b344 100644
> > --- a/kernel/bpf/Kconfig
> > +++ b/kernel/bpf/Kconfig
> > @@ -43,7 +43,7 @@ config BPF_JIT
> >   	bool "Enable BPF Just In Time compiler"
> >   	depends on BPF
> >   	depends on HAVE_CBPF_JIT || HAVE_EBPF_JIT
> > -	depends on MODULES
> > +	select EXECMEM
> >   	help
> >   	  BPF programs are normally handled by a BPF interpreter. This option
> >   	  allows the kernel to generate native code when a program is loaded
> 
> This does not seem to work entirely. If build with BPF_JIT without module
> support for my Raspberry Pi 3 B I get warnings in my kernel log (easiest way
> to trigger it seems to be trying to ssh into it, which fails).

Thanks for the report. I was able to reproduce this using QEMU and it
looks like the problem is because bpf_arch_text_copy() silently fails
to write to the read-only area as a result of patch_map() faulting and
the resulting -EFAULT being chucked away.

Please can you try the diff below?

Will

--->8

diff --git a/arch/arm64/kernel/patching.c b/arch/arm64/kernel/patching.c
index 255534930368..94b9fea65aca 100644
--- a/arch/arm64/kernel/patching.c
+++ b/arch/arm64/kernel/patching.c
@@ -36,7 +36,7 @@ static void __kprobes *patch_map(void *addr, int fixmap)
 
        if (image)
                page = phys_to_page(__pa_symbol(addr));
-       else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+       else if (IS_ENABLED(CONFIG_EXECMEM))
                page = vmalloc_to_page(addr);
        else
                return addr;


  reply	other threads:[~2024-05-17 15:46 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-05 16:06 [PATCH RESEND v8 00/16] mm: jit/text allocator Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 01/16] arm64: module: remove unneeded call to kasan_alloc_module_shadow() Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 02/16] mips: module: rename MODULE_START to MODULES_VADDR Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 03/16] nios2: define virtual address space for modules Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 04/16] sparc: simplify module_alloc() Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 05/16] module: make module_memory_{alloc,free} more self-contained Mike Rapoport
2024-05-07 23:41   ` Masami Hiramatsu
2024-05-05 16:06 ` [PATCH RESEND v8 06/16] mm: introduce execmem_alloc() and execmem_free() Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 07/16] mm/execmem, arch: convert simple overrides of module_alloc to execmem Mike Rapoport
2024-05-07 23:52   ` Masami Hiramatsu
2024-05-05 16:06 ` [PATCH RESEND v8 08/16] mm/execmem, arch: convert remaining " Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 09/16] riscv: extend execmem_params for generated code allocations Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 10/16] arm64: extend execmem_info " Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 11/16] powerpc: extend execmem_params for kprobes allocations Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 12/16] arch: make execmem setup available regardless of CONFIG_MODULES Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 13/16] x86/ftrace: enable dynamic ftrace without CONFIG_MODULES Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 14/16] powerpc: use CONFIG_EXECMEM instead of CONFIG_MODULES where appropriate Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 15/16] kprobes: remove dependency on CONFIG_MODULES Mike Rapoport
2024-05-05 16:06 ` [PATCH RESEND v8 16/16] bpf: remove CONFIG_BPF_JIT dependency on CONFIG_MODULES of Mike Rapoport
2024-05-16 23:00   ` Klara Modin
2024-05-17 15:46     ` Will Deacon [this message]
2024-05-17 16:09       ` Klara Modin
2024-05-05 19:33 ` [PATCH RESEND v8 00/16] mm: jit/text allocator Luis Chamberlain

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