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Message-ID: <CAPhsuW7xE8sz8Nh2AdNb62k=8kgEPxaBCw3w50EfXraxmKca-A@mail.gmail.com>
Date: Fri, 16 Jun 2023 11:53:54 -0700
From: Song Liu <song@...nel.org>
To: Mike Rapoport <rppt@...nel.org>
Cc: linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>, 
	Catalin Marinas <catalin.marinas@....com>, Christophe Leroy <christophe.leroy@...roup.eu>, 
	"David S. Miller" <davem@...emloft.net>, Dinh Nguyen <dinguyen@...nel.org>, 
	Heiko Carstens <hca@...ux.ibm.com>, Helge Deller <deller@....de>, Huacai Chen <chenhuacai@...nel.org>, 
	Kent Overstreet <kent.overstreet@...ux.dev>, Luis Chamberlain <mcgrof@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, Michael Ellerman <mpe@...erman.id.au>, 
	Nadav Amit <nadav.amit@...il.com>, "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Puranjay Mohan <puranjay12@...il.com>, 
	Rick Edgecombe <rick.p.edgecombe@...el.com>, Russell King <linux@...linux.org.uk>, 
	Steven Rostedt <rostedt@...dmis.org>, Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
	Thomas Gleixner <tglx@...utronix.de>, Will Deacon <will@...nel.org>, bpf@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org, 
	linux-mm@...ck.org, linux-modules@...r.kernel.org, 
	linux-parisc@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	linux-s390@...r.kernel.org, linux-trace-kernel@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org, loongarch@...ts.linux.dev, 
	netdev@...r.kernel.org, sparclinux@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH v2 04/12] mm/execmem, arch: convert remaining overrides of
 module_alloc to execmem

On Fri, Jun 16, 2023 at 1:51 AM Mike Rapoport <rppt@...nel.org> wrote:
[...]
> diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
> index 5af4975caeb5..c3d999f3a3dd 100644
> --- a/arch/arm64/kernel/module.c
> +++ b/arch/arm64/kernel/module.c
> @@ -17,56 +17,50 @@
>  #include <linux/moduleloader.h>
>  #include <linux/scs.h>
>  #include <linux/vmalloc.h>
> +#include <linux/execmem.h>
>  #include <asm/alternative.h>
>  #include <asm/insn.h>
>  #include <asm/scs.h>
>  #include <asm/sections.h>
>
> -void *module_alloc(unsigned long size)
> +static struct execmem_params execmem_params = {
> +       .modules = {
> +               .flags = EXECMEM_KASAN_SHADOW,
> +               .text = {
> +                       .alignment = MODULE_ALIGN,
> +               },
> +       },
> +};
> +
> +struct execmem_params __init *execmem_arch_params(void)
>  {
>         u64 module_alloc_end = module_alloc_base + MODULES_VSIZE;
> -       gfp_t gfp_mask = GFP_KERNEL;
> -       void *p;
> -
> -       /* Silence the initial allocation */
> -       if (IS_ENABLED(CONFIG_ARM64_MODULE_PLTS))
> -               gfp_mask |= __GFP_NOWARN;
>
> -       if (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
> -           IS_ENABLED(CONFIG_KASAN_SW_TAGS))
> -               /* don't exceed the static module region - see below */
> -               module_alloc_end = MODULES_END;
> +       execmem_params.modules.text.pgprot = PAGE_KERNEL;
> +       execmem_params.modules.text.start = module_alloc_base;

I think I mentioned this earlier. For arm64 with CONFIG_RANDOMIZE_BASE,
module_alloc_base is not yet set when execmem_arch_params() is
called. So we will need some extra logic for this.

Thanks,
Song


> +       execmem_params.modules.text.end = module_alloc_end;
>
> -       p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base,
> -                               module_alloc_end, gfp_mask, PAGE_KERNEL, VM_DEFER_KMEMLEAK,
> -                               NUMA_NO_NODE, __builtin_return_address(0));
> -
> -       if (!p && IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&
> +       /*
> +        * KASAN without KASAN_VMALLOC can only deal with module
> +        * allocations being served from the reserved module region,
> +        * since the remainder of the vmalloc region is already
> +        * backed by zero shadow pages, and punching holes into it
> +        * is non-trivial. Since the module region is not randomized
> +        * when KASAN is enabled without KASAN_VMALLOC, it is even
> +        * less likely that the module region gets exhausted, so we
> +        * can simply omit this fallback in that case.
> +        */
> +       if (IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&
>             (IS_ENABLED(CONFIG_KASAN_VMALLOC) ||
>              (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
> -             !IS_ENABLED(CONFIG_KASAN_SW_TAGS))))
> -               /*
> -                * KASAN without KASAN_VMALLOC can only deal with module
> -                * allocations being served from the reserved module region,
> -                * since the remainder of the vmalloc region is already
> -                * backed by zero shadow pages, and punching holes into it
> -                * is non-trivial. Since the module region is not randomized
> -                * when KASAN is enabled without KASAN_VMALLOC, it is even
> -                * less likely that the module region gets exhausted, so we
> -                * can simply omit this fallback in that case.
> -                */
> -               p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base,
> -                               module_alloc_base + SZ_2G, GFP_KERNEL,
> -                               PAGE_KERNEL, 0, NUMA_NO_NODE,
> -                               __builtin_return_address(0));
> -
> -       if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
> -               vfree(p);
> -               return NULL;
> +             !IS_ENABLED(CONFIG_KASAN_SW_TAGS)))) {
> +               unsigned long end = module_alloc_base + SZ_2G;
> +
> +               execmem_params.modules.text.fallback_start = module_alloc_base;
> +               execmem_params.modules.text.fallback_end = end;
>         }
>
> -       /* Memory is intended to be executable, reset the pointer tag. */
> -       return kasan_reset_tag(p);
> +       return &execmem_params;
>  }
>
>  enum aarch64_reloc_op {

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