module: replace module_layout with module_memory

module_layout manages different types of memory (text, data, rodata, etc.)
in one allocation, which is problematic for some reasons:

1. It is hard to enable CONFIG_STRICT_MODULE_RWX.
2. It is hard to use huge pages in modules (and not break strict rwx).
3. Many archs uses module_layout for arch-specific data, but it is not
   obvious how these data are used (are they RO, RX, or RW?)

Improve the scenario by replacing 2 (or 3) module_layout per module with
up to 7 module_memory per module:

        MOD_TEXT,
        MOD_DATA,
        MOD_RODATA,
        MOD_RO_AFTER_INIT,
        MOD_INIT_TEXT,
        MOD_INIT_DATA,
        MOD_INIT_RODATA,

and allocating them separately. This adds slightly more entries to
mod_tree (from up to 3 entries per module, to up to 7 entries per
module). However, this at most adds a small constant overhead to
__module_address(), which is expected to be fast.

Various archs use module_layout for different data. These data are put
into different module_memory based on their location in module_layout.
IOW, data that used to go with text is allocated with MOD_MEM_TYPE_TEXT;
data that used to go with data is allocated with MOD_MEM_TYPE_DATA, etc.

module_memory simplifies quite some of the module code. For example,
ARCH_WANTS_MODULES_DATA_IN_VMALLOC is a lot cleaner, as it just uses a
different allocator for the data. kernel/module/strict_rwx.c is also
much cleaner with module_memory.

Signed-off-by: Song Liu <song@kernel.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

1 files changed, 33 insertions, 25 deletions

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index ab2376a1be88..8e89f459ffdd 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -78,6 +78,7 @@ static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs,
 			   unsigned int shnum, unsigned int pcpundx)
 {
 	const Elf_Shdr *sec;
+	enum mod_mem_type type;
 
 	if (src->st_shndx == SHN_UNDEF ||
 	    src->st_shndx >= shnum ||
@@ -90,11 +91,12 @@ static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs,
 #endif
 
 	sec = sechdrs + src->st_shndx;
+	type = sec->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT;
 	if (!(sec->sh_flags & SHF_ALLOC)
 #ifndef CONFIG_KALLSYMS_ALL
 	    || !(sec->sh_flags & SHF_EXECINSTR)
 #endif
-	    || (sec->sh_entsize & INIT_OFFSET_MASK))
+	    || mod_mem_type_is_init(type))
 		return false;
 
 	return true;
@@ -113,11 +115,13 @@ void layout_symtab(struct module *mod, struct load_info *info)
 	Elf_Shdr *strsect = info->sechdrs + info->index.str;
 	const Elf_Sym *src;
 	unsigned int i, nsrc, ndst, strtab_size = 0;
+	struct module_memory *mod_mem_data = &mod->mem[MOD_DATA];
+	struct module_memory *mod_mem_init_data = &mod->mem[MOD_INIT_DATA];
 
 	/* Put symbol section at end of init part of module. */
 	symsect->sh_flags |= SHF_ALLOC;
-	symsect->sh_entsize = module_get_offset(mod, &mod->init_layout.size, symsect,
-						info->index.sym) | INIT_OFFSET_MASK;
+	symsect->sh_entsize = module_get_offset_and_type(mod, MOD_INIT_DATA,
+							 symsect, info->index.sym);
 	pr_debug("\t%s\n", info->secstrings + symsect->sh_name);
 
 	src = (void *)info->hdr + symsect->sh_offset;
@@ -134,28 +138,27 @@ void layout_symtab(struct module *mod, struct load_info *info)
 	}
 
 	/* Append room for core symbols at end of core part. */
-	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->symoffs = ALIGN(mod_mem_data->size, symsect->sh_addralign ?: 1);
+	info->stroffs = mod_mem_data->size = info->symoffs + ndst * sizeof(Elf_Sym);
+	mod_mem_data->size += strtab_size;
 	/* Note add_kallsyms() computes strtab_size as core_typeoffs - stroffs */
-	info->core_typeoffs = mod->data_layout.size;
-	mod->data_layout.size += ndst * sizeof(char);
-	mod->data_layout.size = strict_align(mod->data_layout.size);
+	info->core_typeoffs = mod_mem_data->size;
+	mod_mem_data->size += ndst * sizeof(char);
 
 	/* Put string table section at end of init part of module. */
 	strsect->sh_flags |= SHF_ALLOC;
-	strsect->sh_entsize = module_get_offset(mod, &mod->init_layout.size, strsect,
-						info->index.str) | INIT_OFFSET_MASK;
+	strsect->sh_entsize = module_get_offset_and_type(mod, MOD_INIT_DATA,
+							 strsect, info->index.str);
 	pr_debug("\t%s\n", info->secstrings + strsect->sh_name);
 
 	/* We'll tack temporary mod_kallsyms on the end. */
-	mod->init_layout.size = ALIGN(mod->init_layout.size,
-				      __alignof__(struct mod_kallsyms));
-	info->mod_kallsyms_init_off = mod->init_layout.size;
-	mod->init_layout.size += sizeof(struct mod_kallsyms);
-	info->init_typeoffs = mod->init_layout.size;
-	mod->init_layout.size += nsrc * sizeof(char);
-	mod->init_layout.size = strict_align(mod->init_layout.size);
+	mod_mem_init_data->size = ALIGN(mod_mem_init_data->size,
+					__alignof__(struct mod_kallsyms));
+	info->mod_kallsyms_init_off = mod_mem_init_data->size;
+
+	mod_mem_init_data->size += sizeof(struct mod_kallsyms);
+	info->init_typeoffs = mod_mem_init_data->size;
+	mod_mem_init_data->size += nsrc * sizeof(char);
 }
 
 /*
@@ -171,9 +174,11 @@ void add_kallsyms(struct module *mod, const struct load_info *info)
 	char *s;
 	Elf_Shdr *symsec = &info->sechdrs[info->index.sym];
 	unsigned long strtab_size;
+	void *data_base = mod->mem[MOD_DATA].base;
+	void *init_data_base = mod->mem[MOD_INIT_DATA].base;
 
 	/* Set up to point into init section. */
-	mod->kallsyms = (void __rcu *)mod->init_layout.base +
+	mod->kallsyms = (void __rcu *)init_data_base +
 		info->mod_kallsyms_init_off;
 
 	rcu_read_lock();
@@ -183,15 +188,15 @@ void add_kallsyms(struct module *mod, const struct load_info *info)
 	/* Make sure we get permanent strtab: don't use info->strtab. */
 	rcu_dereference(mod->kallsyms)->strtab =
 		(void *)info->sechdrs[info->index.str].sh_addr;
-	rcu_dereference(mod->kallsyms)->typetab = mod->init_layout.base + info->init_typeoffs;
+	rcu_dereference(mod->kallsyms)->typetab = init_data_base + info->init_typeoffs;
 
 	/*
 	 * 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->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;
+	mod->core_kallsyms.symtab = dst = data_base + info->symoffs;
+	mod->core_kallsyms.strtab = s = data_base + info->stroffs;
+	mod->core_kallsyms.typetab = data_base + info->core_typeoffs;
 	strtab_size = info->core_typeoffs - info->stroffs;
 	src = rcu_dereference(mod->kallsyms)->symtab;
 	for (ndst = i = 0; i < rcu_dereference(mod->kallsyms)->num_symtab; i++) {
@@ -267,12 +272,15 @@ static const char *find_kallsyms_symbol(struct module *mod,
 	unsigned int i, best = 0;
 	unsigned long nextval, bestval;
 	struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);
+	struct module_memory *mod_mem;
 
 	/* At worse, next value is at end of module */
 	if (within_module_init(addr, mod))
-		nextval = (unsigned long)mod->init_layout.base + mod->init_layout.text_size;
+		mod_mem = &mod->mem[MOD_INIT_TEXT];
 	else
-		nextval = (unsigned long)mod->core_layout.base + mod->core_layout.text_size;
+		mod_mem = &mod->mem[MOD_TEXT];
+
+	nextval = (unsigned long)mod_mem->base + mod_mem->size;
 
 	bestval = kallsyms_symbol_value(&kallsyms->symtab[best]);