diff mbox series

[v2,04/12] mm/execmem, arch: convert remaining overrides of module_alloc to execmem

Message ID 20230616085038.4121892-5-rppt@kernel.org (mailing list archive)
State Handled Elsewhere
Headers show
Series mm: jit/text allocator | expand

Commit Message

Mike Rapoport June 16, 2023, 8:50 a.m. UTC 
From: "Mike Rapoport (IBM)" <rppt@kernel.org>

Extend execmem parameters to accommodate more complex overrides of
module_alloc() by architectures.

This includes specification of a fallback range required by arm, arm64
and powerpc and support for allocation of KASAN shadow required by
arm64, s390 and x86.

The core implementation of execmem_alloc() takes care of suppressing
warnings when the initial allocation fails but there is a fallback range
defined.

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
---
 arch/arm/kernel/module.c     | 36 ++++++++++---------
 arch/arm64/kernel/module.c   | 68 ++++++++++++++++--------------------
 arch/powerpc/kernel/module.c | 52 +++++++++++++--------------
 arch/s390/kernel/module.c    | 33 ++++++++---------
 arch/x86/kernel/module.c     | 33 +++++++++--------
 include/linux/execmem.h      | 14 ++++++++
 mm/execmem.c                 | 50 ++++++++++++++++++++++----
 7 files changed, 168 insertions(+), 118 deletions(-)

Comments

Edgecombe, Rick P June 16, 2023, 4:16 p.m. UTC | #1 
On Fri, 2023-06-16 at 11:50 +0300, Mike Rapoport wrote:
> -void *module_alloc(unsigned long size)
> -{
> -       gfp_t gfp_mask = GFP_KERNEL;
> -       void *p;
> -
> -       if (PAGE_ALIGN(size) > MODULES_LEN)
> -               return NULL;
> +static struct execmem_params execmem_params = {
> +       .modules = {
> +               .flags = EXECMEM_KASAN_SHADOW,
> +               .text = {
> +                       .alignment = MODULE_ALIGN,
> +               },
> +       },
> +};

Did you consider making these execmem_params's ro_after_init? Not that
it is security sensitive, but it's a nice hint to the reader that it is
only modified at init. And I guess basically free sanitizing of buggy
writes to it.

>  
> -       p = __vmalloc_node_range(size, MODULE_ALIGN,
> -                                MODULES_VADDR +
> get_module_load_offset(),
> -                                MODULES_END, gfp_mask, PAGE_KERNEL,
> -                                VM_FLUSH_RESET_PERMS |
> VM_DEFER_KMEMLEAK,
> -                                NUMA_NO_NODE,
> __builtin_return_address(0));
> +struct execmem_params __init *execmem_arch_params(void)
> +{
> +       unsigned long start = MODULES_VADDR +
> get_module_load_offset();

I think we can drop the mutex's in get_module_load_offset() now, since
execmem_arch_params() should only be called once at init.

>  
> -       if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0))
> {
> -               vfree(p);
> -               return NULL;
> -       }
> +       execmem_params.modules.text.start = start;
> +       execmem_params.modules.text.end = MODULES_END;
> +       execmem_params.modules.text.pgprot = PAGE_KERNEL;
>  
> -       return p;
> +       return &execmem_params;
>  }
>
Song Liu June 16, 2023, 6:53 p.m. UTC | #2 
On Fri, Jun 16, 2023 at 1:51 AM Mike Rapoport <rppt@kernel.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 {
Mike Rapoport June 17, 2023, 6:10 a.m. UTC | #3 
On Fri, Jun 16, 2023 at 04:16:28PM +0000, Edgecombe, Rick P wrote:
> On Fri, 2023-06-16 at 11:50 +0300, Mike Rapoport wrote:
> > -void *module_alloc(unsigned long size)
> > -{
> > -       gfp_t gfp_mask = GFP_KERNEL;
> > -       void *p;
> > -
> > -       if (PAGE_ALIGN(size) > MODULES_LEN)
> > -               return NULL;
> > +static struct execmem_params execmem_params = {
> > +       .modules = {
> > +               .flags = EXECMEM_KASAN_SHADOW,
> > +               .text = {
> > +                       .alignment = MODULE_ALIGN,
> > +               },
> > +       },
> > +};
> 
> Did you consider making these execmem_params's ro_after_init? Not that
> it is security sensitive, but it's a nice hint to the reader that it is
> only modified at init. And I guess basically free sanitizing of buggy
> writes to it.

Makes sense.
 
> >  
> > -       p = __vmalloc_node_range(size, MODULE_ALIGN,
> > -                                MODULES_VADDR +
> > get_module_load_offset(),
> > -                                MODULES_END, gfp_mask, PAGE_KERNEL,
> > -                                VM_FLUSH_RESET_PERMS |
> > VM_DEFER_KMEMLEAK,
> > -                                NUMA_NO_NODE,
> > __builtin_return_address(0));
> > +struct execmem_params __init *execmem_arch_params(void)
> > +{
> > +       unsigned long start = MODULES_VADDR +
> > get_module_load_offset();
> 
> I think we can drop the mutex's in get_module_load_offset() now, since
> execmem_arch_params() should only be called once at init.

Right. Even more, the entire get_module_load_offset() can be folded into
execmem_arch_params() as 

	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_enabled())
		module_load_offset =
			get_random_u32_inclusive(1, 1024) * PAGE_SIZE;

> >  
> > -       if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0))
> > {
> > -               vfree(p);
> > -               return NULL;
> > -       }
> > +       execmem_params.modules.text.start = start;
> > +       execmem_params.modules.text.end = MODULES_END;
> > +       execmem_params.modules.text.pgprot = PAGE_KERNEL;
> >  
> > -       return p;
> > +       return &execmem_params;
> >  }
> >  
>
Mike Rapoport June 17, 2023, 6:14 a.m. UTC | #4 
On Fri, Jun 16, 2023 at 11:53:54AM -0700, Song Liu wrote:
> On Fri, Jun 16, 2023 at 1:51 AM Mike Rapoport <rppt@kernel.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.

Right, this is taken care of in a later patch, but it actually belongs here.
Good catch!
 
> 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 {
diff mbox series

Patch

diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index d59c36dc0494..f66d479c1c7d 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -16,6 +16,7 @@ 
 #include <linux/fs.h>
 #include <linux/string.h>
 #include <linux/gfp.h>
+#include <linux/execmem.h>
 
 #include <asm/sections.h>
 #include <asm/smp_plat.h>
@@ -34,23 +35,26 @@ 
 #endif
 
 #ifdef CONFIG_MMU
-void *module_alloc(unsigned long size)
+static struct execmem_params execmem_params = {
+	.modules = {
+		.text = {
+			.start = MODULES_VADDR,
+			.end = MODULES_END,
+			.alignment = 1,
+		},
+	},
+};
+
+struct execmem_params __init *execmem_arch_params(void)
 {
-	gfp_t gfp_mask = GFP_KERNEL;
-	void *p;
-
-	/* Silence the initial allocation */
-	if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS))
-		gfp_mask |= __GFP_NOWARN;
-
-	p = __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
-				gfp_mask, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
-				__builtin_return_address(0));
-	if (!IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || p)
-		return p;
-	return __vmalloc_node_range(size, 1,  VMALLOC_START, VMALLOC_END,
-				GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
-				__builtin_return_address(0));
+	execmem_params.modules.text.pgprot = PAGE_KERNEL_EXEC;
+
+	if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS)) {
+		execmem_params.modules.text.fallback_start = VMALLOC_START;
+		execmem_params.modules.text.fallback_end = VMALLOC_END;
+	}
+
+	return &execmem_params;
 }
 #endif
 
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;
+	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 {
diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
index f6d6ae0a1692..ba7abff77d98 100644
--- a/arch/powerpc/kernel/module.c
+++ b/arch/powerpc/kernel/module.c
@@ -10,6 +10,7 @@ 
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
 #include <linux/bug.h>
+#include <linux/execmem.h>
 #include <asm/module.h>
 #include <linux/uaccess.h>
 #include <asm/firmware.h>
@@ -89,39 +90,38 @@  int module_finalize(const Elf_Ehdr *hdr,
 	return 0;
 }
 
-static __always_inline void *
-__module_alloc(unsigned long size, unsigned long start, unsigned long end, bool nowarn)
+static struct execmem_params execmem_params = {
+	.modules = {
+		.text = {
+			.alignment = 1,
+		},
+	},
+};
+
+
+struct execmem_params __init *execmem_arch_params(void)
 {
 	pgprot_t prot = strict_module_rwx_enabled() ? PAGE_KERNEL : PAGE_KERNEL_EXEC;
-	gfp_t gfp = GFP_KERNEL | (nowarn ? __GFP_NOWARN : 0);
-
-	/*
-	 * Don't do huge page allocations for modules yet until more testing
-	 * is done. STRICT_MODULE_RWX may require extra work to support this
-	 * too.
-	 */
-	return __vmalloc_node_range(size, 1, start, end, gfp, prot,
-				    VM_FLUSH_RESET_PERMS,
-				    NUMA_NO_NODE, __builtin_return_address(0));
-}
 
-void *module_alloc(unsigned long size)
-{
 #ifdef MODULES_VADDR
 	unsigned long limit = (unsigned long)_etext - SZ_32M;
-	void *ptr = NULL;
-
-	BUILD_BUG_ON(TASK_SIZE > MODULES_VADDR);
 
 	/* First try within 32M limit from _etext to avoid branch trampolines */
-	if (MODULES_VADDR < PAGE_OFFSET && MODULES_END > limit)
-		ptr = __module_alloc(size, limit, MODULES_END, true);
-
-	if (!ptr)
-		ptr = __module_alloc(size, MODULES_VADDR, MODULES_END, false);
-
-	return ptr;
+	if (MODULES_VADDR < PAGE_OFFSET && MODULES_END > limit) {
+		execmem_params.modules.text.start = limit;
+		execmem_params.modules.text.end = MODULES_END;
+		execmem_params.modules.text.fallback_start = MODULES_VADDR;
+		execmem_params.modules.text.fallback_end = MODULES_END;
+	} else {
+		execmem_params.modules.text.start = MODULES_VADDR;
+		execmem_params.modules.text.end = MODULES_END;
+	}
 #else
-	return __module_alloc(size, VMALLOC_START, VMALLOC_END, false);
+	execmem_params.modules.text.start = VMALLOC_START;
+	execmem_params.modules.text.end = VMALLOC_END;
 #endif
+
+	execmem_params.modules.text.pgprot = prot;
+
+	return &execmem_params;
 }
diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c
index 4a844683dc76..7fff395d26ea 100644
--- a/arch/s390/kernel/module.c
+++ b/arch/s390/kernel/module.c
@@ -55,23 +55,24 @@  static unsigned long get_module_load_offset(void)
 	return module_load_offset;
 }
 
-void *module_alloc(unsigned long size)
+static struct execmem_params execmem_params = {
+	.modules = {
+		.flags = EXECMEM_KASAN_SHADOW,
+		.text = {
+			.alignment = MODULE_ALIGN,
+			.pgprot = PAGE_KERNEL,
+		},
+	},
+};
+
+struct execmem_params __init *execmem_arch_params(void)
 {
-	gfp_t gfp_mask = GFP_KERNEL;
-	void *p;
-
-	if (PAGE_ALIGN(size) > MODULES_LEN)
-		return NULL;
-	p = __vmalloc_node_range(size, MODULE_ALIGN,
-				 MODULES_VADDR + get_module_load_offset(),
-				 MODULES_END, gfp_mask, PAGE_KERNEL,
-				 VM_FLUSH_RESET_PERMS | VM_DEFER_KMEMLEAK,
-				 NUMA_NO_NODE, __builtin_return_address(0));
-	if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
-		vfree(p);
-		return NULL;
-	}
-	return p;
+	unsigned long start = MODULES_VADDR + get_module_load_offset();
+
+	execmem_params.modules.text.start = start;
+	execmem_params.modules.text.end = MODULES_END;
+
+	return &execmem_params;
 }
 
 #ifdef CONFIG_FUNCTION_TRACER
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index b05f62ee2344..cf9a7d0a8b62 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -19,6 +19,7 @@ 
 #include <linux/jump_label.h>
 #include <linux/random.h>
 #include <linux/memory.h>
+#include <linux/execmem.h>
 
 #include <asm/text-patching.h>
 #include <asm/page.h>
@@ -65,26 +66,24 @@  static unsigned long int get_module_load_offset(void)
 }
 #endif
 
-void *module_alloc(unsigned long size)
-{
-	gfp_t gfp_mask = GFP_KERNEL;
-	void *p;
-
-	if (PAGE_ALIGN(size) > MODULES_LEN)
-		return NULL;
+static struct execmem_params execmem_params = {
+	.modules = {
+		.flags = EXECMEM_KASAN_SHADOW,
+		.text = {
+			.alignment = MODULE_ALIGN,
+		},
+	},
+};
 
-	p = __vmalloc_node_range(size, MODULE_ALIGN,
-				 MODULES_VADDR + get_module_load_offset(),
-				 MODULES_END, gfp_mask, PAGE_KERNEL,
-				 VM_FLUSH_RESET_PERMS | VM_DEFER_KMEMLEAK,
-				 NUMA_NO_NODE, __builtin_return_address(0));
+struct execmem_params __init *execmem_arch_params(void)
+{
+	unsigned long start = MODULES_VADDR + get_module_load_offset();
 
-	if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
-		vfree(p);
-		return NULL;
-	}
+	execmem_params.modules.text.start = start;
+	execmem_params.modules.text.end = MODULES_END;
+	execmem_params.modules.text.pgprot = PAGE_KERNEL;
 
-	return p;
+	return &execmem_params;
 }
 
 #ifdef CONFIG_X86_32
diff --git a/include/linux/execmem.h b/include/linux/execmem.h
index 75946f23731e..68b2bfc79993 100644
--- a/include/linux/execmem.h
+++ b/include/linux/execmem.h
@@ -9,22 +9,36 @@ 
  *			  related data allocations
  * @start:	address space start
  * @end:	address space end (inclusive)
+ * @fallback_start:	start of the range for fallback allocations
+ * @fallback_end:	end of the range for fallback allocations (inclusive)
  * @pgprot:	permisssions for memory in this address space
  * @alignment:	alignment required for text allocations
  */
 struct execmem_range {
 	unsigned long   start;
 	unsigned long   end;
+	unsigned long   fallback_start;
+	unsigned long   fallback_end;
 	pgprot_t        pgprot;
 	unsigned int	alignment;
 };
 
+/**
+ * enum execmem_module_flags - options for executable memory allocations
+ * @EXECMEM_KASAN_SHADOW:	allocate kasan shadow
+ */
+enum execmem_module_flags {
+	EXECMEM_KASAN_SHADOW	= (1 << 0),
+};
+
 /**
  * struct execmem_modules_range - architecure parameters for modules address
  *				  space
+ * @flags:	options for module memory allocations
  * @text:	address range for text allocations
  */
 struct execmem_modules_range {
+	enum execmem_module_flags flags;
 	struct execmem_range text;
 };
 
diff --git a/mm/execmem.c b/mm/execmem.c
index c92878cf4d1a..2fe36dcc7bdf 100644
--- a/mm/execmem.c
+++ b/mm/execmem.c
@@ -7,12 +7,46 @@ 
 
 struct execmem_params execmem_params;
 
-static void *execmem_alloc(size_t size, unsigned long start, unsigned long end,
-			   unsigned int align, pgprot_t pgprot)
+static void *execmem_alloc(size_t len, unsigned long start, unsigned long end,
+			   unsigned int alignment, pgprot_t pgprot,
+			   unsigned long fallback_start,
+			   unsigned long fallback_end,
+			   bool kasan)
 {
-	return __vmalloc_node_range(size, align, start, end,
-				   GFP_KERNEL, pgprot, VM_FLUSH_RESET_PERMS,
-				   NUMA_NO_NODE, __builtin_return_address(0));
+	unsigned long vm_flags  = VM_FLUSH_RESET_PERMS;
+	bool fallback  = !!fallback_start;
+	gfp_t gfp_flags = GFP_KERNEL;
+	void *p;
+
+	if (PAGE_ALIGN(len) > (end - start))
+		return NULL;
+
+	if (kasan)
+		vm_flags |= VM_DEFER_KMEMLEAK;
+
+	if (fallback)
+		gfp_flags |= __GFP_NOWARN;
+
+	p = __vmalloc_node_range(len, alignment, start, end, gfp_flags,
+				 pgprot, vm_flags, NUMA_NO_NODE,
+				 __builtin_return_address(0));
+
+	if (!p && fallback) {
+		start = fallback_start;
+		end = fallback_end;
+		gfp_flags = GFP_KERNEL;
+
+		p = __vmalloc_node_range(len, alignment, start, end, gfp_flags,
+					 pgprot, vm_flags, NUMA_NO_NODE,
+					 __builtin_return_address(0));
+	}
+
+	if (p && kasan && (kasan_alloc_module_shadow(p, len, GFP_KERNEL) < 0)) {
+		vfree(p);
+		return NULL;
+	}
+
+	return kasan_reset_tag(p);
 }
 
 void *execmem_text_alloc(size_t size)
@@ -21,11 +55,15 @@  void *execmem_text_alloc(size_t size)
 	unsigned long end = execmem_params.modules.text.end;
 	pgprot_t pgprot = execmem_params.modules.text.pgprot;
 	unsigned int align = execmem_params.modules.text.alignment;
+	unsigned long fallback_start = execmem_params.modules.text.fallback_start;
+	unsigned long fallback_end = execmem_params.modules.text.fallback_end;
+	bool kasan = execmem_params.modules.flags & EXECMEM_KASAN_SHADOW;
 
 	if (!execmem_params.modules.text.start)
 		return module_alloc(size);
 
-	return execmem_alloc(size, start, end, align, pgprot);
+	return execmem_alloc(size, start, end, align, pgprot,
+			     fallback_start, fallback_end, kasan);
 }
 
 void execmem_free(void *ptr)