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Message-Id: <50797bbf84acd87c490192ae5b8539ee67b71418.1645607143.git.christophe.leroy@csgroup.eu>
Date: Wed, 23 Feb 2022 13:02:13 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Luis Chamberlain <mcgrof@...nel.org>,
Aaron Tomlin <atomlin@...hat.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
kgdb-bugreport@...ts.sourceforge.net, linux-mm@...ck.org,
linux-arch@...r.kernel.org, linux-modules@...r.kernel.org
Subject: [PATCH v6 3/6] module: Introduce data_layout
In order to allow separation of data from text, add another layout,
called data_layout. For architectures requesting separation of text
and data, only text will go in core_layout and data will go in
data_layout.
For architectures which keep text and data together, make data_layout
an alias of core_layout, that way data_layout can be used for all
data manipulations, regardless of whether data is in core_layout or
data_layout.
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
kernel/module/internal.h | 2 ++
kernel/module/kallsyms.c | 18 +++++++++---------
kernel/module/main.c | 20 ++++++++++++--------
kernel/module/strict_rwx.c | 10 +++++-----
4 files changed, 28 insertions(+), 22 deletions(-)
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 0f3146347256..0aabbf5cbcd1 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -20,6 +20,8 @@
/* Maximum number of characters written by module_flags() */
#define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)
+#define data_layout core_layout
+
/*
* Modules' sections will be aligned on page boundaries
* to ensure complete separation of code and data, but
diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 23034b50f8f5..c56de1686172 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -134,12 +134,12 @@ void layout_symtab(struct module *mod, struct load_info *info)
}
/* Append room for core symbols at end of core part. */
- info->symoffs = ALIGN(mod->core_layout.size, symsect->sh_addralign ?: 1);
- info->stroffs = mod->core_layout.size = info->symoffs + ndst * sizeof(Elf_Sym);
- mod->core_layout.size += strtab_size;
- info->core_typeoffs = mod->core_layout.size;
- mod->core_layout.size += ndst * sizeof(char);
- mod->core_layout.size = strict_align(mod->core_layout.size);
+ info->symoffs = ALIGN(mod->data_layout.size, symsect->sh_addralign ?: 1);
+ info->stroffs = mod->data_layout.size = info->symoffs + ndst * sizeof(Elf_Sym);
+ mod->data_layout.size += strtab_size;
+ info->core_typeoffs = mod->data_layout.size;
+ mod->data_layout.size += ndst * sizeof(char);
+ mod->data_layout.size = strict_align(mod->data_layout.size);
/* Put string table section at end of init part of module. */
strsect->sh_flags |= SHF_ALLOC;
@@ -187,9 +187,9 @@ void add_kallsyms(struct module *mod, const struct load_info *info)
* Now populate the cut down core kallsyms for after init
* and set types up while we still have access to sections.
*/
- mod->core_kallsyms.symtab = dst = mod->core_layout.base + info->symoffs;
- mod->core_kallsyms.strtab = s = mod->core_layout.base + info->stroffs;
- mod->core_kallsyms.typetab = mod->core_layout.base + info->core_typeoffs;
+ mod->core_kallsyms.symtab = dst = mod->data_layout.base + info->symoffs;
+ mod->core_kallsyms.strtab = s = mod->data_layout.base + info->stroffs;
+ mod->core_kallsyms.typetab = mod->data_layout.base + info->core_typeoffs;
src = rcu_dereference_sched(mod->kallsyms)->symtab;
for (ndst = i = 0; i < rcu_dereference_sched(mod->kallsyms)->num_symtab; i++) {
rcu_dereference_sched(mod->kallsyms)->typetab[i] = elf_type(src + i, info);
diff --git a/kernel/module/main.c b/kernel/module/main.c
index a831f51595d7..84db7318ba2b 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -1190,7 +1190,7 @@ static void free_module(struct module *mod)
percpu_modfree(mod);
/* Free lock-classes; relies on the preceding sync_rcu(). */
- lockdep_free_key_range(mod->core_layout.base, mod->core_layout.size);
+ lockdep_free_key_range(mod->data_layout.base, mod->data_layout.size);
/* Finally, free the core (containing the module structure) */
module_memfree(mod->core_layout.base);
@@ -1431,13 +1431,15 @@ static void layout_sections(struct module *mod, struct load_info *info)
for (i = 0; i < info->hdr->e_shnum; ++i) {
Elf_Shdr *s = &info->sechdrs[i];
const char *sname = info->secstrings + s->sh_name;
+ unsigned int *sizep;
if ((s->sh_flags & masks[m][0]) != masks[m][0]
|| (s->sh_flags & masks[m][1])
|| s->sh_entsize != ~0UL
|| module_init_layout_section(sname))
continue;
- s->sh_entsize = module_get_offset(mod, &mod->core_layout.size, s, i);
+ sizep = m ? &mod->data_layout.size : &mod->core_layout.size;
+ s->sh_entsize = module_get_offset(mod, sizep, s, i);
pr_debug("\t%s\n", sname);
}
switch (m) {
@@ -1446,15 +1448,15 @@ static void layout_sections(struct module *mod, struct load_info *info)
mod->core_layout.text_size = mod->core_layout.size;
break;
case 1: /* RO: text and ro-data */
- mod->core_layout.size = strict_align(mod->core_layout.size);
- mod->core_layout.ro_size = mod->core_layout.size;
+ mod->data_layout.size = strict_align(mod->data_layout.size);
+ mod->data_layout.ro_size = mod->data_layout.size;
break;
case 2: /* RO after init */
- mod->core_layout.size = strict_align(mod->core_layout.size);
- mod->core_layout.ro_after_init_size = mod->core_layout.size;
+ mod->data_layout.size = strict_align(mod->data_layout.size);
+ mod->data_layout.ro_after_init_size = mod->data_layout.size;
break;
case 4: /* whole core */
- mod->core_layout.size = strict_align(mod->core_layout.size);
+ mod->data_layout.size = strict_align(mod->data_layout.size);
break;
}
}
@@ -2134,6 +2136,8 @@ static int move_module(struct module *mod, struct load_info *info)
if (shdr->sh_entsize & INIT_OFFSET_MASK)
dest = mod->init_layout.base
+ (shdr->sh_entsize & ~INIT_OFFSET_MASK);
+ else if (!(shdr->sh_flags & SHF_EXECINSTR))
+ dest = mod->data_layout.base + shdr->sh_entsize;
else
dest = mod->core_layout.base + shdr->sh_entsize;
@@ -2829,7 +2833,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
mutex_unlock(&module_mutex);
free_module:
/* Free lock-classes; relies on the preceding sync_rcu() */
- lockdep_free_key_range(mod->core_layout.base, mod->core_layout.size);
+ lockdep_free_key_range(mod->data_layout.base, mod->data_layout.size);
module_deallocate(mod, info);
free_copy:
diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c
index f36ea54c1dac..fe3c10891407 100644
--- a/kernel/module/strict_rwx.c
+++ b/kernel/module/strict_rwx.c
@@ -101,12 +101,12 @@ void module_enable_ro(const struct module *mod, bool after_init)
set_vm_flush_reset_perms(mod->init_layout.base);
frob_text(&mod->core_layout, set_memory_ro);
- frob_rodata(&mod->core_layout, set_memory_ro);
+ frob_rodata(&mod->data_layout, set_memory_ro);
frob_text(&mod->init_layout, set_memory_ro);
frob_rodata(&mod->init_layout, set_memory_ro);
if (after_init)
- frob_ro_after_init(&mod->core_layout, set_memory_ro);
+ frob_ro_after_init(&mod->data_layout, set_memory_ro);
}
void module_enable_nx(const struct module *mod)
@@ -114,9 +114,9 @@ void module_enable_nx(const struct module *mod)
if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
return;
- frob_rodata(&mod->core_layout, set_memory_nx);
- frob_ro_after_init(&mod->core_layout, set_memory_nx);
- frob_writable_data(&mod->core_layout, set_memory_nx);
+ frob_rodata(&mod->data_layout, set_memory_nx);
+ frob_ro_after_init(&mod->data_layout, set_memory_nx);
+ frob_writable_data(&mod->data_layout, set_memory_nx);
frob_rodata(&mod->init_layout, set_memory_nx);
frob_writable_data(&mod->init_layout, set_memory_nx);
}
--
2.34.1
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