The patch titled
Subject: mm: introduce execmem_text_alloc() and execmem_free()
has been added to the -mm mm-unstable branch. Its filename is
mm-introduce-execmem_text_alloc-and-execmem_free.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-introduce-execmem_text_alloc-and-execmem_free.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: "Mike Rapoport (IBM)" <rppt@xxxxxxxxxx>
Subject: mm: introduce execmem_text_alloc() and execmem_free()
Date: Mon, 18 Sep 2023 10:29:44 +0300
module_alloc() is used everywhere as a mean to allocate memory for code.
Beside being semantically wrong, this unnecessarily ties all subsystems
that need to allocate code, such as ftrace, kprobes and BPF to modules and
puts the burden of code allocation to the modules code.
Several architectures override module_alloc() because of various
constraints where the executable memory can be located and this causes
additional obstacles for improvements of code allocation.
Start splitting code allocation from modules by introducing
execmem_text_alloc() and execmem_free() APIs.
Initially, execmem_text_alloc() is a wrapper for module_alloc() and
execmem_free() is a replacement of module_memfree() to allow updating all
call sites to use the new APIs.
Since architectures define different restrictions on placement,
permissions, alignment and other parameters for memory that can be used by
different subsystems that allocate executable memory, execmem_text_alloc()
takes a type argument, that will be used to identify the calling subsystem
and to allow architectures define parameters for ranges suitable for that
subsystem.
The name execmem_text_alloc() emphasizes that the allocated memory is for
executable code, the allocations of the associated data, like data
sections of a module will use execmem_data_alloc() interface that will be
added later.
Link: https://lkml.kernel.org/r/20230918072955.2507221-3-rppt@xxxxxxxxxx
Signed-off-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Björn Töpel <bjorn@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Dinh Nguyen <dinguyen@xxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Helge Deller <deller@xxxxxx>
Cc: Huacai Chen <chenhuacai@xxxxxxxxxx>
Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nadav Amit <nadav.amit@xxxxxxxxx>
Cc: "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Puranjay Mohan <puranjay12@xxxxxxxxx>
Cc: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Cc: Russell King (Oracle) <linux@xxxxxxxxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Cc: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/kprobes.c | 4 +-
arch/s390/kernel/ftrace.c | 4 +-
arch/s390/kernel/kprobes.c | 4 +-
arch/s390/kernel/module.c | 5 +-
arch/sparc/net/bpf_jit_comp_32.c | 8 ++--
arch/x86/kernel/ftrace.c | 6 +--
arch/x86/kernel/kprobes/core.c | 4 +-
include/linux/execmem.h | 56 +++++++++++++++++++++++++++++
include/linux/moduleloader.h | 3 -
kernel/bpf/core.c | 6 +--
kernel/kprobes.c | 8 ++--
kernel/module/Kconfig | 1
kernel/module/main.c | 25 ++++--------
mm/Kconfig | 3 +
mm/Makefile | 1
mm/execmem.c | 26 +++++++++++++
16 files changed, 120 insertions(+), 44 deletions(-)
--- a/arch/powerpc/kernel/kprobes.c~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/arch/powerpc/kernel/kprobes.c
@@ -19,8 +19,8 @@
#include <linux/extable.h>
#include <linux/kdebug.h>
#include <linux/slab.h>
-#include <linux/moduleloader.h>
#include <linux/set_memory.h>
+#include <linux/execmem.h>
#include <asm/code-patching.h>
#include <asm/cacheflush.h>
#include <asm/sstep.h>
@@ -130,7 +130,7 @@ void *alloc_insn_page(void)
{
void *page;
- page = module_alloc(PAGE_SIZE);
+ page = execmem_text_alloc(EXECMEM_KPROBES, PAGE_SIZE);
if (!page)
return NULL;
--- a/arch/s390/kernel/ftrace.c~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/arch/s390/kernel/ftrace.c
@@ -7,13 +7,13 @@
* Author(s): Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
*/
-#include <linux/moduleloader.h>
#include <linux/hardirq.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/kprobes.h>
+#include <linux/execmem.h>
#include <trace/syscall.h>
#include <asm/asm-offsets.h>
#include <asm/text-patching.h>
@@ -220,7 +220,7 @@ static int __init ftrace_plt_init(void)
{
const char *start, *end;
- ftrace_plt = module_alloc(PAGE_SIZE);
+ ftrace_plt = execmem_text_alloc(EXECMEM_FTRACE, PAGE_SIZE);
if (!ftrace_plt)
panic("cannot allocate ftrace plt\n");
--- a/arch/s390/kernel/kprobes.c~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/arch/s390/kernel/kprobes.c
@@ -9,7 +9,6 @@
#define pr_fmt(fmt) "kprobes: " fmt
-#include <linux/moduleloader.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/preempt.h>
@@ -21,6 +20,7 @@
#include <linux/slab.h>
#include <linux/hardirq.h>
#include <linux/ftrace.h>
+#include <linux/execmem.h>
#include <asm/set_memory.h>
#include <asm/sections.h>
#include <asm/dis.h>
@@ -38,7 +38,7 @@ void *alloc_insn_page(void)
{
void *page;
- page = module_alloc(PAGE_SIZE);
+ page = execmem_text_alloc(EXECMEM_KPROBES, PAGE_SIZE);
if (!page)
return NULL;
set_memory_rox((unsigned long)page, 1);
--- a/arch/s390/kernel/module.c~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/arch/s390/kernel/module.c
@@ -21,6 +21,7 @@
#include <linux/moduleloader.h>
#include <linux/bug.h>
#include <linux/memory.h>
+#include <linux/execmem.h>
#include <asm/alternative.h>
#include <asm/nospec-branch.h>
#include <asm/facility.h>
@@ -76,7 +77,7 @@ void *module_alloc(unsigned long size)
#ifdef CONFIG_FUNCTION_TRACER
void module_arch_cleanup(struct module *mod)
{
- module_memfree(mod->arch.trampolines_start);
+ execmem_free(mod->arch.trampolines_start);
}
#endif
@@ -510,7 +511,7 @@ static int module_alloc_ftrace_hotpatch_
size = FTRACE_HOTPATCH_TRAMPOLINES_SIZE(s->sh_size);
numpages = DIV_ROUND_UP(size, PAGE_SIZE);
- start = module_alloc(numpages * PAGE_SIZE);
+ start = execmem_text_alloc(EXECMEM_FTRACE, numpages * PAGE_SIZE);
if (!start)
return -ENOMEM;
set_memory_rox((unsigned long)start, numpages);
--- a/arch/sparc/net/bpf_jit_comp_32.c~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/arch/sparc/net/bpf_jit_comp_32.c
@@ -1,10 +1,10 @@
// SPDX-License-Identifier: GPL-2.0
-#include <linux/moduleloader.h>
#include <linux/workqueue.h>
#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/cache.h>
#include <linux/if_vlan.h>
+#include <linux/execmem.h>
#include <asm/cacheflush.h>
#include <asm/ptrace.h>
@@ -713,7 +713,7 @@ cond_branch: f_offset = addrs[i + filt
if (unlikely(proglen + ilen > oldproglen)) {
pr_err("bpb_jit_compile fatal error\n");
kfree(addrs);
- module_memfree(image);
+ execmem_free(image);
return;
}
memcpy(image + proglen, temp, ilen);
@@ -736,7 +736,7 @@ cond_branch: f_offset = addrs[i + filt
break;
}
if (proglen == oldproglen) {
- image = module_alloc(proglen);
+ image = execmem_text_alloc(EXECMEM_BPF, proglen);
if (!image)
goto out;
}
@@ -758,7 +758,7 @@ out:
void bpf_jit_free(struct bpf_prog *fp)
{
if (fp->jited)
- module_memfree(fp->bpf_func);
+ execmem_free(fp->bpf_func);
bpf_prog_unlock_free(fp);
}
--- a/arch/x86/kernel/ftrace.c~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/arch/x86/kernel/ftrace.c
@@ -25,6 +25,7 @@
#include <linux/memory.h>
#include <linux/vmalloc.h>
#include <linux/set_memory.h>
+#include <linux/execmem.h>
#include <trace/syscall.h>
@@ -261,15 +262,14 @@ void arch_ftrace_update_code(int command
#ifdef CONFIG_X86_64
#ifdef CONFIG_MODULES
-#include <linux/moduleloader.h>
/* Module allocation simplifies allocating memory for code */
static inline void *alloc_tramp(unsigned long size)
{
- return module_alloc(size);
+ return execmem_text_alloc(EXECMEM_FTRACE, size);
}
static inline void tramp_free(void *tramp)
{
- module_memfree(tramp);
+ execmem_free(tramp);
}
#else
/* Trampolines can only be created if modules are supported */
--- a/arch/x86/kernel/kprobes/core.c~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/arch/x86/kernel/kprobes/core.c
@@ -40,12 +40,12 @@
#include <linux/kgdb.h>
#include <linux/ftrace.h>
#include <linux/kasan.h>
-#include <linux/moduleloader.h>
#include <linux/objtool.h>
#include <linux/vmalloc.h>
#include <linux/pgtable.h>
#include <linux/set_memory.h>
#include <linux/cfi.h>
+#include <linux/execmem.h>
#include <asm/text-patching.h>
#include <asm/cacheflush.h>
@@ -448,7 +448,7 @@ void *alloc_insn_page(void)
{
void *page;
- page = module_alloc(PAGE_SIZE);
+ page = execmem_text_alloc(EXECMEM_KPROBES, PAGE_SIZE);
if (!page)
return NULL;
--- /dev/null
+++ a/include/linux/execmem.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_EXECMEM_ALLOC_H
+#define _LINUX_EXECMEM_ALLOC_H
+
+#include <linux/types.h>
+
+/**
+ * enum execmem_type - types of executable memory ranges
+ *
+ * There are several subsystems that allocate executable memory.
+ * Architectures define different restrictions on placement,
+ * permissions, alignment and other parameters for memory that can be used
+ * by these subsystems.
+ * Types in this enum identify subsystems that allocate executable memory
+ * and let architectures define parameters for ranges suitable for
+ * allocations by each subsystem.
+ *
+ * @EXECMEM_DEFAULT: default parameters that would be used for types that
+ * are not explcitly defined.
+ * @EXECMEM_MODULE_TEXT: parameters for module text sections
+ * @EXECMEM_KPROBES: parameters for kprobes
+ * @EXECMEM_FTRACE: parameters for ftrace
+ * @EXECMEM_BPF: parameters for BPF
+ * @EXECMEM_TYPE_MAX:
+ */
+enum execmem_type {
+ EXECMEM_DEFAULT,
+ EXECMEM_MODULE_TEXT = EXECMEM_DEFAULT,
+ EXECMEM_KPROBES,
+ EXECMEM_FTRACE,
+ EXECMEM_BPF,
+ EXECMEM_TYPE_MAX,
+};
+
+/**
+ * execmem_text_alloc - allocate executable memory
+ * @type: type of the allocation
+ * @size: how many bytes of memory are required
+ *
+ * Allocates memory that will contain executable code, either generated or
+ * loaded from kernel modules.
+ *
+ * The memory will have protections defined by architecture for executable
+ * region of the @type.
+ *
+ * Return: a pointer to the allocated memory or %NULL
+ */
+void *execmem_text_alloc(enum execmem_type type, size_t size);
+
+/**
+ * execmem_free - free executable memory
+ * @ptr: pointer to the memory that should be freed
+ */
+void execmem_free(void *ptr);
+
+#endif /* _LINUX_EXECMEM_ALLOC_H */
--- a/include/linux/moduleloader.h~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/include/linux/moduleloader.h
@@ -29,9 +29,6 @@ unsigned int arch_mod_section_prepend(st
sections. Returns NULL on failure. */
void *module_alloc(unsigned long size);
-/* Free memory returned from module_alloc. */
-void module_memfree(void *module_region);
-
/* Determines if the section name is an init section (that is only used during
* module loading).
*/
--- a/kernel/bpf/core.c~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/kernel/bpf/core.c
@@ -22,7 +22,6 @@
#include <linux/skbuff.h>
#include <linux/vmalloc.h>
#include <linux/random.h>
-#include <linux/moduleloader.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/objtool.h>
@@ -37,6 +36,7 @@
#include <linux/nospec.h>
#include <linux/bpf_mem_alloc.h>
#include <linux/memcontrol.h>
+#include <linux/execmem.h>
#include <asm/barrier.h>
#include <asm/unaligned.h>
@@ -1007,12 +1007,12 @@ void bpf_jit_uncharge_modmem(u32 size)
void *__weak bpf_jit_alloc_exec(unsigned long size)
{
- return module_alloc(size);
+ return execmem_text_alloc(EXECMEM_BPF, size);
}
void __weak bpf_jit_free_exec(void *addr)
{
- module_memfree(addr);
+ execmem_free(addr);
}
struct bpf_binary_header *
--- a/kernel/kprobes.c~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/kernel/kprobes.c
@@ -26,7 +26,6 @@
#include <linux/slab.h>
#include <linux/stddef.h>
#include <linux/export.h>
-#include <linux/moduleloader.h>
#include <linux/kallsyms.h>
#include <linux/freezer.h>
#include <linux/seq_file.h>
@@ -39,6 +38,7 @@
#include <linux/jump_label.h>
#include <linux/static_call.h>
#include <linux/perf_event.h>
+#include <linux/execmem.h>
#include <asm/sections.h>
#include <asm/cacheflush.h>
@@ -113,17 +113,17 @@ enum kprobe_slot_state {
void __weak *alloc_insn_page(void)
{
/*
- * Use module_alloc() so this page is within +/- 2GB of where the
+ * Use execmem_text_alloc() so this page is within +/- 2GB of where the
* kernel image and loaded module images reside. This is required
* for most of the architectures.
* (e.g. x86-64 needs this to handle the %rip-relative fixups.)
*/
- return module_alloc(PAGE_SIZE);
+ return execmem_text_alloc(EXECMEM_KPROBES, PAGE_SIZE);
}
static void free_insn_page(void *page)
{
- module_memfree(page);
+ execmem_free(page);
}
struct kprobe_insn_cache kprobe_insn_slots = {
--- a/kernel/module/Kconfig~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/kernel/module/Kconfig
@@ -2,6 +2,7 @@
menuconfig MODULES
bool "Enable loadable module support"
modules
+ select EXECMEM
help
Kernel modules are small pieces of compiled code which can
be inserted in the running kernel, rather than being
--- a/kernel/module/main.c~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/kernel/module/main.c
@@ -57,6 +57,7 @@
#include <linux/audit.h>
#include <linux/cfi.h>
#include <linux/debugfs.h>
+#include <linux/execmem.h>
#include <uapi/linux/module.h>
#include "internal.h"
@@ -1179,16 +1180,6 @@ resolve_symbol_wait(struct module *mod,
return ksym;
}
-void __weak module_memfree(void *module_region)
-{
- /*
- * This memory may be RO, and freeing RO memory in an interrupt is not
- * supported by vmalloc.
- */
- WARN_ON(in_interrupt());
- vfree(module_region);
-}
-
void __weak module_arch_cleanup(struct module *mod)
{
}
@@ -1207,7 +1198,7 @@ static void *module_memory_alloc(unsigne
{
if (mod_mem_use_vmalloc(type))
return vzalloc(size);
- return module_alloc(size);
+ return execmem_text_alloc(EXECMEM_MODULE_TEXT, size);
}
static void module_memory_free(void *ptr, enum mod_mem_type type)
@@ -1215,7 +1206,7 @@ static void module_memory_free(void *ptr
if (mod_mem_use_vmalloc(type))
vfree(ptr);
else
- module_memfree(ptr);
+ execmem_free(ptr);
}
static void free_mod_mem(struct module *mod)
@@ -2479,9 +2470,9 @@ static void do_free_init(struct work_str
llist_for_each_safe(pos, n, list) {
initfree = container_of(pos, struct mod_initfree, node);
- module_memfree(initfree->init_text);
- module_memfree(initfree->init_data);
- module_memfree(initfree->init_rodata);
+ execmem_free(initfree->init_text);
+ execmem_free(initfree->init_data);
+ execmem_free(initfree->init_rodata);
kfree(initfree);
}
}
@@ -2584,10 +2575,10 @@ static noinline int do_init_module(struc
* We want to free module_init, but be aware that kallsyms may be
* walking this with preempt disabled. In all the failure paths, we
* call synchronize_rcu(), but we don't want to slow down the success
- * path. module_memfree() cannot be called in an interrupt, so do the
+ * path. execmem_free() cannot be called in an interrupt, so do the
* work and call synchronize_rcu() in a work queue.
*
- * Note that module_alloc() on most architectures creates W+X page
+ * Note that execmem_text_alloc() on most architectures creates W+X page
* mappings which won't be cleaned up until do_free_init() runs. Any
* code such as mark_rodata_ro() which depends on those mappings to
* be cleaned up needs to sync with the queued work - ie
--- /dev/null
+++ a/mm/execmem.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/execmem.h>
+#include <linux/moduleloader.h>
+
+static void *execmem_alloc(size_t size)
+{
+ return module_alloc(size);
+}
+
+void *execmem_text_alloc(enum execmem_type type, size_t size)
+{
+ return execmem_alloc(size);
+}
+
+void execmem_free(void *ptr)
+{
+ /*
+ * This memory may be RO, and freeing RO memory in an interrupt is not
+ * supported by vmalloc.
+ */
+ WARN_ON(in_interrupt());
+ vfree(ptr);
+}
--- a/mm/Kconfig~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/mm/Kconfig
@@ -1259,6 +1259,9 @@ config LOCK_MM_AND_FIND_VMA
bool
depends on !STACK_GROWSUP
+config EXECMEM
+ bool
+
source "mm/damon/Kconfig"
endmenu
--- a/mm/Makefile~mm-introduce-execmem_text_alloc-and-execmem_free
+++ a/mm/Makefile
@@ -138,3 +138,4 @@ obj-$(CONFIG_IO_MAPPING) += io-mapping.o
obj-$(CONFIG_HAVE_BOOTMEM_INFO_NODE) += bootmem_info.o
obj-$(CONFIG_GENERIC_IOREMAP) += ioremap.o
obj-$(CONFIG_SHRINKER_DEBUG) += shrinker_debug.o
+obj-$(CONFIG_EXECMEM) += execmem.o
_
Patches currently in -mm which might be from rppt@xxxxxxxxxx are
nios2-define-virtual-address-space-for-modules.patch
mm-introduce-execmem_text_alloc-and-execmem_free.patch
mm-execmem-arch-convert-simple-overrides-of-module_alloc-to-execmem.patch
mm-execmem-arch-convert-remaining-overrides-of-module_alloc-to-execmem.patch
modules-execmem-drop-module_alloc.patch
mm-execmem-introduce-execmem_data_alloc.patch
arm64-execmem-extend-execmem_params-for-generated-code-allocations.patch
riscv-extend-execmem_params-for-generated-code-allocations.patch
powerpc-extend-execmem_params-for-kprobes-allocations.patch
arch-make-execmem-setup-available-regardless-of-config_modules.patch
x86-ftrace-enable-dynamic-ftrace-without-config_modules.patch
kprobes-remove-dependency-on-config_modules.patch
bpf-remove-config_bpf_jit-dependency-on-config_modules-of.patch
