From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Calvin Owens <jcalvinowens@gmail.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alexei Starovoitov <ast@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Naveen N Rao <naveen.n.rao@linux.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
David S Miller <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>
Cc: "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"linux-modules@vger.kernel.org" <linux-modules@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH 1/4] module: mm: Make module_alloc() generally available
Date: Thu, 7 Mar 2024 14:43:50 +0000 [thread overview]
Message-ID: <267d9173-2a0e-4006-a858-4e94aeff94df@csgroup.eu> (raw)
In-Reply-To: <a6b162aed1e6fea7f565ef9dd0204d6f2284bcce.1709676663.git.jcalvinowens@gmail.com>
Hi Calvin,
Le 06/03/2024 à 21:05, Calvin Owens a écrit :
> [Vous ne recevez pas souvent de courriers de jcalvinowens@gmail.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>
> Both BPF_JIT and KPROBES depend on CONFIG_MODULES, but only require
> module_alloc() itself, which can be easily separated into a standalone
> allocator for executable kernel memory.
Easily maybe, but not as easily as you think, see below.
>
> Thomas Gleixner sent a patch to do that for x86 as part of a larger
> series a couple years ago:
>
> https://lore.kernel.org/all/20220716230953.442937066@linutronix.de/
>
> I've simply extended that approach to the whole kernel.
>
> Signed-off-by: Calvin Owens <jcalvinowens@gmail.com>
> ---
> arch/Kconfig | 2 +-
> arch/arm/kernel/module.c | 35 ---------
> arch/arm/mm/Makefile | 2 +
> arch/arm/mm/module_alloc.c | 40 ++++++++++
> arch/arm64/kernel/module.c | 127 ------------------------------
> arch/arm64/mm/Makefile | 1 +
> arch/arm64/mm/module_alloc.c | 130 +++++++++++++++++++++++++++++++
> arch/loongarch/kernel/module.c | 6 --
> arch/loongarch/mm/Makefile | 2 +
> arch/loongarch/mm/module_alloc.c | 10 +++
> arch/mips/kernel/module.c | 10 ---
> arch/mips/mm/Makefile | 2 +
> arch/mips/mm/module_alloc.c | 13 ++++
> arch/nios2/kernel/module.c | 20 -----
> arch/nios2/mm/Makefile | 2 +
> arch/nios2/mm/module_alloc.c | 22 ++++++
> arch/parisc/kernel/module.c | 12 ---
> arch/parisc/mm/Makefile | 1 +
> arch/parisc/mm/module_alloc.c | 15 ++++
> arch/powerpc/kernel/module.c | 36 ---------
> arch/powerpc/mm/Makefile | 1 +
> arch/powerpc/mm/module_alloc.c | 41 ++++++++++
Missing several powerpc changes to make it work. You must audit every
use of CONFIG_MODULES inside powerpc. Here are a few exemples:
Function get_patch_pfn() to enable text code patching.
arch/powerpc/Kconfig : select KASAN_VMALLOC if KASAN && MODULES
arch/powerpc/include/asm/kasan.h:
#if defined(CONFIG_MODULES) && defined(CONFIG_PPC32)
#define KASAN_KERN_START ALIGN_DOWN(PAGE_OFFSET - SZ_256M, SZ_256M)
#else
#define KASAN_KERN_START PAGE_OFFSET
#endif
arch/powerpc/kernel/head_8xx.S and arch/powerpc/kernel/head_book3s_32.S:
InstructionTLBMiss interrupt handler must know that there is executable
kernel text outside kernel core.
Function is_module_segment() to identified segments used for module text
and set NX (NoExec) MMU flag on non-module segments.
> arch/riscv/kernel/module.c | 11 ---
> arch/riscv/mm/Makefile | 1 +
> arch/riscv/mm/module_alloc.c | 17 ++++
> arch/s390/kernel/module.c | 37 ---------
> arch/s390/mm/Makefile | 1 +
> arch/s390/mm/module_alloc.c | 42 ++++++++++
> arch/sparc/kernel/module.c | 31 --------
> arch/sparc/mm/Makefile | 2 +
> arch/sparc/mm/module_alloc.c | 31 ++++++++
> arch/x86/kernel/ftrace.c | 2 +-
> arch/x86/kernel/module.c | 56 -------------
> arch/x86/mm/Makefile | 2 +
> arch/x86/mm/module_alloc.c | 59 ++++++++++++++
> fs/proc/kcore.c | 2 +-
> kernel/module/Kconfig | 1 +
> kernel/module/main.c | 17 ----
> mm/Kconfig | 3 +
> mm/Makefile | 1 +
> mm/module_alloc.c | 21 +++++
> mm/vmalloc.c | 2 +-
> 42 files changed, 467 insertions(+), 402 deletions(-)
...
> diff --git a/mm/Kconfig b/mm/Kconfig
> index ffc3a2ba3a8c..92bfb5ae2e95 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -1261,6 +1261,9 @@ config LOCK_MM_AND_FIND_VMA
> config IOMMU_MM_DATA
> bool
>
> +config MODULE_ALLOC
> + def_bool n
> +
I'd call it something else than CONFIG_MODULE_ALLOC as you want to use
it when CONFIG_MODULE is not selected.
Something like CONFIG_EXECMEM_ALLOC or CONFIG_DYNAMIC_EXECMEM ?
Christophe
next prev parent reply other threads:[~2024-03-07 14:43 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-06 20:05 [RFC][PATCH 0/4] Make bpf_jit and kprobes work with CONFIG_MODULES=n Calvin Owens
2024-03-06 20:05 ` [RFC][PATCH 1/4] module: mm: Make module_alloc() generally available Calvin Owens
2024-03-07 14:43 ` Christophe Leroy [this message]
2024-03-08 20:53 ` Calvin Owens
2024-03-08 2:16 ` Masami Hiramatsu
2024-03-08 20:43 ` Calvin Owens
2024-03-06 20:05 ` [RFC][PATCH 2/4] bpf: Allow BPF_JIT with CONFIG_MODULES=n Calvin Owens
2024-03-07 22:09 ` Christophe Leroy
2024-03-08 21:04 ` Calvin Owens
2024-03-06 20:05 ` [RFC][PATCH 3/4] kprobes: Allow kprobes " Calvin Owens
2024-03-07 7:22 ` Mike Rapoport
2024-03-08 2:46 ` Masami Hiramatsu
2024-03-08 20:36 ` Calvin Owens
2024-03-07 22:16 ` Christophe Leroy
2024-03-08 21:02 ` Calvin Owens
2024-03-08 2:46 ` Masami Hiramatsu
2024-03-08 20:57 ` Calvin Owens
2024-03-06 20:05 ` [RFC][PATCH 4/4] selftests/bpf: Support testing the !MODULES case Calvin Owens
2024-03-06 21:34 ` [RFC][PATCH 0/4] Make bpf_jit and kprobes work with CONFIG_MODULES=n Luis Chamberlain
2024-03-06 23:23 ` Calvin Owens
2024-03-07 1:58 ` Song Liu
2024-03-08 2:50 ` Masami Hiramatsu
2024-03-08 2:55 ` Luis Chamberlain
2024-03-08 20:27 ` Calvin Owens
2024-03-07 7:13 ` Mike Rapoport
2024-03-08 2:45 ` Masami Hiramatsu
2024-03-25 22:46 ` Jarkko Sakkinen
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