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Subject[PATCH 5/7] modules: Introduce data_layout
Date
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@csgroup.eu>
---
kernel/module.c | 52 ++++++++++++++++++++++++++++---------------------
1 file changed, 30 insertions(+), 22 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 051fecef416b..de1a9de6a544 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -81,6 +81,8 @@
/* If this is set, the section belongs in the init part of the module */
#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))

+#define data_layout core_layout
+
/*
* Mutex protects:
* 1) List of modules (also safely readable with preempt_disable),
@@ -2012,19 +2014,20 @@ static 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);
}

static void module_enable_nx(const struct module *mod)
{
- 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);
}
@@ -2202,7 +2205,7 @@ 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);
@@ -2449,7 +2452,10 @@ static void layout_sections(struct module *mod, struct load_info *info)
|| s->sh_entsize != ~0UL
|| module_init_layout_section(sname))
continue;
- s->sh_entsize = get_offset(mod, &mod->core_layout.size, s, i);
+ if (m)
+ s->sh_entsize = get_offset(mod, &mod->data_layout.size, s, i);
+ else
+ s->sh_entsize = get_offset(mod, &mod->core_layout.size, s, i);
pr_debug("\t%s\n", sname);
}
switch (m) {
@@ -2458,15 +2464,15 @@ 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 = debug_align(mod->core_layout.size);
- mod->core_layout.ro_size = mod->core_layout.size;
+ mod->data_layout.size = debug_align(mod->data_layout.size);
+ mod->data_layout.ro_size = mod->data_layout.size;
break;
case 2: /* RO after init */
- mod->core_layout.size = debug_align(mod->core_layout.size);
- mod->core_layout.ro_after_init_size = mod->core_layout.size;
+ mod->data_layout.size = debug_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 = debug_align(mod->core_layout.size);
+ mod->data_layout.size = debug_align(mod->data_layout.size);
break;
}
}
@@ -2719,12 +2725,12 @@ static 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 = debug_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 = debug_align(mod->data_layout.size);

/* Put string table section at end of init part of module. */
strsect->sh_flags |= SHF_ALLOC;
@@ -2768,9 +2774,9 @@ static 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 = mod->kallsyms->symtab;
for (ndst = i = 0; i < mod->kallsyms->num_symtab; i++) {
mod->kallsyms->typetab[i] = elf_type(src + i, info);
@@ -3462,6 +3468,8 @@ 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;

@@ -4167,7 +4175,7 @@ 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:
--
2.33.1
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