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module: Add CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC

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Add CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC to allow architectures
to request having modules data in vmalloc area instead of module area.

This is required on powerpc book3s/32 in order to set data non
executable, because it is not possible to set executability on page
basis, this is done per 256 Mbytes segments. The module area has exec
right, vmalloc area has noexec.

This can also be useful on other powerpc/32 in order to maximize the
chance of code being close enough to kernel core to avoid branch
trampolines.

Cc: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mcgrof: rebased in light of kernel/module/kdb.c move]
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
This commit is contained in:
Christophe Leroy 2022-02-23 13:02:14 +01:00 committed by Luis Chamberlain
parent 6ab9942c44
commit 01dc0386ef
8 changed files with 96 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/Kconfig
View File

@ -888,6 +888,12 @@ config MODULES_USE_ELF_REL
Modules only use ELF REL relocations. Modules with ELF RELA
relocations will give an error.
config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
bool
help
For architectures like powerpc/32 which have constraints on module
allocation and need to allocate module data outside of module area.
config HAVE_IRQ_EXIT_ON_IRQ_STACK
bool
help

8
include/linux/module.h
View File

@ -422,6 +422,9 @@ struct module {
/* Core layout: rbtree is accessed frequently, so keep together. */
struct module_layout core_layout __module_layout_align;
struct module_layout init_layout;
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
struct module_layout data_layout;
#endif
/* Arch-specific module values */
struct mod_arch_specific arch;
@ -569,6 +572,11 @@ bool is_module_text_address(unsigned long addr);
static inline bool within_module_core(unsigned long addr,
const struct module *mod)
{
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
if ((unsigned long)mod->data_layout.base <= addr &&
addr < (unsigned long)mod->data_layout.base + mod->data_layout.size)
return true;
#endif
return (unsigned long)mod->core_layout.base <= addr &&
addr < (unsigned long)mod->core_layout.base + mod->core_layout.size;
}

3
kernel/module/internal.h
View File

@ -20,7 +20,9 @@
/* Maximum number of characters written by module_flags() */
#define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)
#ifndef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
#define data_layout core_layout
#endif
/*
* Modules' sections will be aligned on page boundaries
@ -154,6 +156,7 @@ struct mod_tree_root {
};
extern struct mod_tree_root mod_tree;
extern struct mod_tree_root mod_data_tree;
#ifdef CONFIG_MODULES_TREE_LOOKUP
void mod_tree_insert(struct module *mod);

10
kernel/module/kdb.c
View File

@ -26,8 +26,11 @@ int kdb_lsmod(int argc, const char **argv)
if (mod->state == MODULE_STATE_UNFORMED)
continue;
kdb_printf("%-20s%8u 0x%px ", mod->name,
mod->core_layout.size, (void *)mod);
kdb_printf("%-20s%8u", mod->name, mod->core_layout.size);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
kdb_printf("/%8u", mod->data_layout.size);
#endif
kdb_printf(" 0x%px ", (void *)mod);
#ifdef CONFIG_MODULE_UNLOAD
kdb_printf("%4d ", module_refcount(mod));
#endif
@ -38,6 +41,9 @@ int kdb_lsmod(int argc, const char **argv)
else
kdb_printf(" (Live)");
kdb_printf(" 0x%px", mod->core_layout.base);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
kdb_printf("/0x%px", mod->data_layout.base);
#endif
#ifdef CONFIG_MODULE_UNLOAD
{

58
kernel/module/main.c
View File

@ -78,6 +78,12 @@ struct mod_tree_root mod_tree __cacheline_aligned = {
.addr_min = -1UL,
};
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
struct mod_tree_root mod_data_tree __cacheline_aligned = {
.addr_min = -1UL,
};
#endif
#define module_addr_min mod_tree.addr_min
#define module_addr_max mod_tree.addr_max
@ -107,6 +113,9 @@ static void mod_update_bounds(struct module *mod)
__mod_update_bounds(mod->core_layout.base, mod->core_layout.size, &mod_tree);
if (mod->init_layout.size)
__mod_update_bounds(mod->init_layout.base, mod->init_layout.size, &mod_tree);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
__mod_update_bounds(mod->data_layout.base, mod->data_layout.size, &mod_data_tree);
#endif
}
static void module_assert_mutex_or_preempt(void)
@ -940,6 +949,17 @@ static ssize_t show_coresize(struct module_attribute *mattr,
static struct module_attribute modinfo_coresize =
__ATTR(coresize, 0444, show_coresize, NULL);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
static ssize_t show_datasize(struct module_attribute *mattr,
struct module_kobject *mk, char *buffer)
{
return sprintf(buffer, "%u\n", mk->mod->data_layout.size);
}
static struct module_attribute modinfo_datasize =
__ATTR(datasize, 0444, show_datasize, NULL);
#endif
static ssize_t show_initsize(struct module_attribute *mattr,
struct module_kobject *mk, char *buffer)
{
@ -968,6 +988,9 @@ struct module_attribute *modinfo_attrs[] = {
&modinfo_srcversion,
&modinfo_initstate,
&modinfo_coresize,
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
&modinfo_datasize,
#endif
&modinfo_initsize,
&modinfo_taint,
#ifdef CONFIG_MODULE_UNLOAD
@ -1194,6 +1217,9 @@ static void free_module(struct module *mod)
/* Finally, free the core (containing the module structure) */
module_memfree(mod->core_layout.base);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
vfree(mod->data_layout.base);
#endif
}
void *__symbol_get(const char *symbol)
@ -2124,6 +2150,24 @@ static int move_module(struct module *mod, struct load_info *info)
} else
mod->init_layout.base = NULL;
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
/* Do the allocs. */
ptr = vmalloc(mod->data_layout.size);
/*
* The pointer to this block is stored in the module structure
* which is inside the block. Just mark it as not being a
* leak.
*/
kmemleak_not_leak(ptr);
if (!ptr) {
module_memfree(mod->core_layout.base);
module_memfree(mod->init_layout.base);
return -ENOMEM;
}
memset(ptr, 0, mod->data_layout.size);
mod->data_layout.base = ptr;
#endif
/* Transfer each section which specifies SHF_ALLOC */
pr_debug("final section addresses:\n");
for (i = 0; i < info->hdr->e_shnum; i++) {
@ -2299,6 +2343,9 @@ static void module_deallocate(struct module *mod, struct load_info *info)
module_arch_freeing_init(mod);
module_memfree(mod->init_layout.base);
module_memfree(mod->core_layout.base);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
vfree(mod->data_layout.base);
#endif
}
int __weak module_finalize(const Elf_Ehdr *hdr,
@ -3015,13 +3062,20 @@ bool is_module_address(unsigned long addr)
struct module *__module_address(unsigned long addr)
{
struct module *mod;
struct mod_tree_root *tree;
if (addr < module_addr_min || addr > module_addr_max)
if (addr >= mod_tree.addr_min && addr <= mod_tree.addr_max)
tree = &mod_tree;
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
else if (addr >= mod_data_tree.addr_min && addr <= mod_data_tree.addr_max)
tree = &mod_data_tree;
#endif
else
return NULL;
module_assert_mutex_or_preempt();
mod = mod_find(addr, &mod_tree);
mod = mod_find(addr, tree);
if (mod) {
BUG_ON(!within_module(addr, mod));
if (mod->state == MODULE_STATE_UNFORMED)

8
kernel/module/procfs.c
View File

@ -67,13 +67,17 @@ static int m_show(struct seq_file *m, void *p)
struct module *mod = list_entry(p, struct module, list);
char buf[MODULE_FLAGS_BUF_SIZE];
void *value;
unsigned int size;
/* We always ignore unformed modules. */
if (mod->state == MODULE_STATE_UNFORMED)
return 0;
seq_printf(m, "%s %u",
mod->name, mod->init_layout.size + mod->core_layout.size);
size = mod->init_layout.size + mod->core_layout.size;
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
size += mod->data_layout.size;
#endif
seq_printf(m, "%s %u", mod->name, size);
print_unload_info(m, mod);
/* Informative for users. */

1
kernel/module/strict_rwx.c
View File

@ -75,6 +75,7 @@ bool module_check_misalignment(const struct module *mod)
return false;
return layout_check_misalignment(&mod->core_layout) ||
layout_check_misalignment(&mod->data_layout) ||
layout_check_misalignment(&mod->init_layout);
}

8
kernel/module/tree_lookup.c
View File

@ -83,6 +83,11 @@ void mod_tree_insert(struct module *mod)
__mod_tree_insert(&mod->core_layout.mtn, &mod_tree);
if (mod->init_layout.size)
__mod_tree_insert(&mod->init_layout.mtn, &mod_tree);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
mod->data_layout.mtn.mod = mod;
__mod_tree_insert(&mod->data_layout.mtn, &mod_data_tree);
#endif
}
void mod_tree_remove_init(struct module *mod)
@ -95,6 +100,9 @@ void mod_tree_remove(struct module *mod)
{
__mod_tree_remove(&mod->core_layout.mtn, &mod_tree);
mod_tree_remove_init(mod);
#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
__mod_tree_remove(&mod->data_layout.mtn, &mod_data_tree);
#endif
}
struct module *mod_find(unsigned long addr, struct mod_tree_root *tree)