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

Mike Rapoport
2023-06-16T08:52:12Z

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(-)

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)
--
2.35.1