[PATCH v3 04/13] mm/execmem, arch: convert remaining overrides of module_alloc to execmem

From: Mike Rapoport
Date: Mon Sep 18 2023 - 03:31:56 EST

From: "Mike Rapoport (IBM)" <rppt@xxxxxxxxxx>

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@xxxxxxxxxx>
---
arch/arm/kernel/module.c | 38 ++++++++++++---------
arch/arm64/kernel/module.c | 57 ++++++++++++++------------------
arch/powerpc/kernel/module.c | 52 ++++++++++++++---------------
arch/s390/kernel/module.c | 52 +++++++++++------------------
arch/x86/kernel/module.c | 64 +++++++++++-------------------------
include/linux/execmem.h | 14 ++++++++
mm/execmem.c | 43 ++++++++++++++++++++++--
7 files changed, 167 insertions(+), 153 deletions(-)

diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index e74d84f58b77..2c7651a2d84c 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 +35,28 @@
#endif

#ifdef CONFIG_MMU
-void *module_alloc(unsigned long size)
+static struct execmem_params execmem_params __ro_after_init = {
+ .ranges = {
+ [EXECMEM_DEFAULT] = {
+ .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));
+ struct execmem_range *r = &execmem_params.ranges[EXECMEM_DEFAULT];
+
+ r->pgprot = PAGE_KERNEL_EXEC;
+
+ if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS)) {
+ r->fallback_start = VMALLOC_START;
+ r->fallback_end = VMALLOC_END;
+ }
+
+ return &execmem_params;
}
#endif

diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index dd851297596e..cd6320de1c54 100644
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -20,6 +20,7 @@
#include <linux/random.h>
#include <linux/scs.h>
#include <linux/vmalloc.h>
+#include <linux/execmem.h>

#include <asm/alternative.h>
#include <asm/insn.h>
@@ -108,46 +109,38 @@ static int __init module_init_limits(void)

return 0;
}
-subsys_initcall(module_init_limits);

-void *module_alloc(unsigned long size)
+static struct execmem_params execmem_params __ro_after_init = {
+ .ranges = {
+ [EXECMEM_DEFAULT] = {
+ .flags = EXECMEM_KASAN_SHADOW,
+ .alignment = MODULE_ALIGN,
+ },
+ },
+};
+
+struct execmem_params __init *execmem_arch_params(void)
{
- void *p = NULL;
+ struct execmem_range *r = &execmem_params.ranges[EXECMEM_DEFAULT];

- /*
- * Where possible, prefer to allocate within direct branch range of the
- * kernel such that no PLTs are necessary.
- */
- if (module_direct_base) {
- p = __vmalloc_node_range(size, MODULE_ALIGN,
- module_direct_base,
- module_direct_base + SZ_128M,
- GFP_KERNEL | __GFP_NOWARN,
- PAGE_KERNEL, 0, NUMA_NO_NODE,
- __builtin_return_address(0));
- }
+ module_init_limits();

- if (!p && module_plt_base) {
- p = __vmalloc_node_range(size, MODULE_ALIGN,
- module_plt_base,
- module_plt_base + SZ_2G,
- GFP_KERNEL | __GFP_NOWARN,
- PAGE_KERNEL, 0, NUMA_NO_NODE,
- __builtin_return_address(0));
- }
+ r->pgprot = PAGE_KERNEL;

- if (!p) {
- pr_warn_ratelimited("%s: unable to allocate memory\n",
- __func__);
- }
+ if (module_direct_base) {
+ r->start = module_direct_base;
+ r->end = module_direct_base + SZ_128M;

- if (p && (kasan_alloc_module_shadow(p, size, GFP_KERNEL) < 0)) {
- vfree(p);
- return NULL;
+ if (module_plt_base) {
+ r->fallback_start = module_plt_base;
+ r->fallback_end = module_plt_base + SZ_2G;
+ }
+ } else if (module_plt_base) {
+ r->start = module_plt_base;
+ r->end = module_plt_base + SZ_2G;
}

- /* 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..f4dd26f693a3 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 __ro_after_init = {
+ .ranges = {
+ [EXECMEM_DEFAULT] = {
+ .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));
-}
+ struct execmem_range *range = &execmem_params.ranges[EXECMEM_DEFAULT];

-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) {
+ range->start = limit;
+ range->end = MODULES_END;
+ range->fallback_start = MODULES_VADDR;
+ range->fallback_end = MODULES_END;
+ } else {
+ range->start = MODULES_VADDR;
+ range->end = MODULES_END;
+ }
#else
- return __module_alloc(size, VMALLOC_START, VMALLOC_END, false);
+ range->start = VMALLOC_START;
+ range->end = VMALLOC_END;
#endif
+
+ range->pgprot = prot;
+
+ return &execmem_params;
}
diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c
index db5561d0c233..538d5f24af66 100644
--- a/arch/s390/kernel/module.c
+++ b/arch/s390/kernel/module.c
@@ -37,41 +37,29 @@

#define PLT_ENTRY_SIZE 22

-static unsigned long get_module_load_offset(void)
+static struct execmem_params execmem_params __ro_after_init = {
+ .ranges = {
+ [EXECMEM_DEFAULT] = {
+ .flags = EXECMEM_KASAN_SHADOW,
+ .alignment = MODULE_ALIGN,
+ .pgprot = PAGE_KERNEL,
+ },
+ },
+};
+
+struct execmem_params __init *execmem_arch_params(void)
{
- static DEFINE_MUTEX(module_kaslr_mutex);
- static unsigned long module_load_offset;
-
- if (!kaslr_enabled())
- return 0;
- /*
- * Calculate the module_load_offset the first time this code
- * is called. Once calculated it stays the same until reboot.
- */
- mutex_lock(&module_kaslr_mutex);
- if (!module_load_offset)
+ unsigned long module_load_offset = 0;
+ unsigned long start;
+
+ if (kaslr_enabled())
module_load_offset = get_random_u32_inclusive(1, 1024) * PAGE_SIZE;
- mutex_unlock(&module_kaslr_mutex);
- return module_load_offset;
-}

-void *module_alloc(unsigned long size)
-{
- 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;
+ start = MODULES_VADDR + module_load_offset;
+ execmem_params.ranges[EXECMEM_DEFAULT].start = start;
+ execmem_params.ranges[EXECMEM_DEFAULT].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 5f71a0cf4399..9d37375e2f05 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>
@@ -36,55 +37,30 @@ do { \
} while (0)
#endif

-#ifdef CONFIG_RANDOMIZE_BASE
-static unsigned long module_load_offset;
+static struct execmem_params execmem_params __ro_after_init = {
+ .ranges = {
+ [EXECMEM_DEFAULT] = {
+ .flags = EXECMEM_KASAN_SHADOW,
+ .alignment = MODULE_ALIGN,
+ },
+ },
+};

-/* Mutex protects the module_load_offset. */
-static DEFINE_MUTEX(module_kaslr_mutex);
-
-static unsigned long int get_module_load_offset(void)
-{
- if (kaslr_enabled()) {
- mutex_lock(&module_kaslr_mutex);
- /*
- * Calculate the module_load_offset the first time this
- * code is called. Once calculated it stays the same until
- * reboot.
- */
- if (module_load_offset == 0)
- module_load_offset =
- get_random_u32_inclusive(1, 1024) * PAGE_SIZE;
- mutex_unlock(&module_kaslr_mutex);
- }
- return module_load_offset;
-}
-#else
-static unsigned long int get_module_load_offset(void)
-{
- return 0;
-}
-#endif
-
-void *module_alloc(unsigned long size)
+struct execmem_params __init *execmem_arch_params(void)
{
- gfp_t gfp_mask = GFP_KERNEL;
- void *p;
-
- if (PAGE_ALIGN(size) > MODULES_LEN)
- return NULL;
+ unsigned long module_load_offset = 0;
+ unsigned long start;

- 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 (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;
- }
+ start = MODULES_VADDR + module_load_offset;
+ execmem_params.ranges[EXECMEM_DEFAULT].start = start;
+ execmem_params.ranges[EXECMEM_DEFAULT].end = MODULES_END;
+ execmem_params.ranges[EXECMEM_DEFAULT].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 44e213625053..806ad1a0088d 100644
--- a/include/linux/execmem.h
+++ b/include/linux/execmem.h
@@ -32,19 +32,33 @@ enum execmem_type {
EXECMEM_TYPE_MAX,
};

+/**
+ * enum execmem_module_flags - options for executable memory allocations
+ * @EXECMEM_KASAN_SHADOW: allocate kasan shadow
+ */
+enum execmem_range_flags {
+ EXECMEM_KASAN_SHADOW = (1 << 0),
+};
+
/**
* struct execmem_range - definition of a memory range suitable for code and
* 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: permissions for memory in this address space
* @alignment: alignment required for text allocations
+ * @flags: options for memory allocations for this range
*/
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_range_flags flags;
};

/**
diff --git a/mm/execmem.c b/mm/execmem.c
index f25a5e064886..a8c2f44d0133 100644
--- a/mm/execmem.c
+++ b/mm/execmem.c
@@ -11,12 +11,46 @@ static void *execmem_alloc(size_t size, struct execmem_range *range)
{
unsigned long start = range->start;
unsigned long end = range->end;
+ unsigned long fallback_start = range->fallback_start;
+ unsigned long fallback_end = range->fallback_end;
unsigned int align = range->alignment;
pgprot_t pgprot = range->pgprot;
+ bool kasan = range->flags & EXECMEM_KASAN_SHADOW;
+ unsigned long vm_flags = VM_FLUSH_RESET_PERMS;
+ bool fallback = !!fallback_start;
+ gfp_t gfp_flags = GFP_KERNEL;
+ void *p;

- return __vmalloc_node_range(size, align, start, end,
- GFP_KERNEL, pgprot, VM_FLUSH_RESET_PERMS,
- NUMA_NO_NODE, __builtin_return_address(0));
+ if (PAGE_ALIGN(size) > (end - start))
+ return NULL;
+
+ if (kasan)
+ vm_flags |= VM_DEFER_KMEMLEAK;
+
+ if (fallback)
+ gfp_flags |= __GFP_NOWARN;
+
+ p = __vmalloc_node_range(size, align, 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(size, align, start, end, gfp_flags,
+ pgprot, vm_flags, NUMA_NO_NODE,
+ __builtin_return_address(0));
+ }
+
+ if (p && kasan &&
+ (kasan_alloc_module_shadow(p, size, GFP_KERNEL) < 0)) {
+ vfree(p);
+ return NULL;
+ }
+
+ return kasan_reset_tag(p);
}

void *execmem_text_alloc(enum execmem_type type, size_t size)
@@ -66,6 +100,9 @@ static void execmem_init_missing(struct execmem_params *p)
r->alignment = default_range->alignment;
r->start = default_range->start;
r->end = default_range->end;
+ r->flags = default_range->flags;
+ r->fallback_start = default_range->fallback_start;
+ r->fallback_end = default_range->fallback_end;
}
}
}
--
2.39.2