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, 18 insertions, 81 deletions

diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c
index 14fbea66f12f..a2b656b4e3d2 100644
--- a/kernel/module/strict_rwx.c
+++ b/kernel/module/strict_rwx.c
@@ -11,82 +11,25 @@
 #include <linux/set_memory.h>
 #include "internal.h"
 
-/*
- * LKM RO/NX protection: protect module's text/ro-data
- * from modification and any data from execution.
- *
- * General layout of module is:
- *          [text] [read-only-data] [ro-after-init] [writable data]
- * text_size -----^                ^               ^               ^
- * ro_size ------------------------|               |               |
- * ro_after_init_size -----------------------------|               |
- * size -----------------------------------------------------------|
- *
- * These values are always page-aligned (as is base) when
- * CONFIG_STRICT_MODULE_RWX is set.
- */
+static void module_set_memory(const struct module *mod, enum mod_mem_type type,
+			      int (*set_memory)(unsigned long start, int num_pages))
+{
+	const struct module_memory *mod_mem = &mod->mem[type];
+
+	set_vm_flush_reset_perms(mod_mem->base);
+	set_memory((unsigned long)mod_mem->base, mod_mem->size >> PAGE_SHIFT);
+}
 
 /*
  * Since some arches are moving towards PAGE_KERNEL module allocations instead
- * of PAGE_KERNEL_EXEC, keep frob_text() and module_enable_x() independent of
+ * of PAGE_KERNEL_EXEC, keep module_enable_x() independent of
  * CONFIG_STRICT_MODULE_RWX because they are needed regardless of whether we
  * are strict.
  */
-static void frob_text(const struct module_layout *layout,
-		      int (*set_memory)(unsigned long start, int num_pages))
-{
-	set_memory((unsigned long)layout->base,
-		   PAGE_ALIGN(layout->text_size) >> PAGE_SHIFT);
-}
-
-static void frob_rodata(const struct module_layout *layout,
-		 int (*set_memory)(unsigned long start, int num_pages))
-{
-	set_memory((unsigned long)layout->base + layout->text_size,
-		   (layout->ro_size - layout->text_size) >> PAGE_SHIFT);
-}
-
-static void frob_ro_after_init(const struct module_layout *layout,
-			int (*set_memory)(unsigned long start, int num_pages))
-{
-	set_memory((unsigned long)layout->base + layout->ro_size,
-		   (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT);
-}
-
-static void frob_writable_data(const struct module_layout *layout,
-			int (*set_memory)(unsigned long start, int num_pages))
-{
-	set_memory((unsigned long)layout->base + layout->ro_after_init_size,
-		   (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT);
-}
-
-static bool layout_check_misalignment(const struct module_layout *layout)
-{
-	return WARN_ON(!PAGE_ALIGNED(layout->base)) ||
-	       WARN_ON(!PAGE_ALIGNED(layout->text_size)) ||
-	       WARN_ON(!PAGE_ALIGNED(layout->ro_size)) ||
-	       WARN_ON(!PAGE_ALIGNED(layout->ro_after_init_size)) ||
-	       WARN_ON(!PAGE_ALIGNED(layout->size));
-}
-
-bool module_check_misalignment(const struct module *mod)
-{
-	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
-		return false;
-
-	return layout_check_misalignment(&mod->core_layout) ||
-	       layout_check_misalignment(&mod->data_layout) ||
-	       layout_check_misalignment(&mod->init_layout);
-}
-
 void module_enable_x(const struct module *mod)
 {
-	if (!PAGE_ALIGNED(mod->core_layout.base) ||
-	    !PAGE_ALIGNED(mod->init_layout.base))
-		return;
-
-	frob_text(&mod->core_layout, set_memory_x);
-	frob_text(&mod->init_layout, set_memory_x);
+	for_class_mod_mem_type(type, text)
+		module_set_memory(mod, type, set_memory_x);
 }
 
 void module_enable_ro(const struct module *mod, bool after_init)
@@ -98,16 +41,13 @@ void module_enable_ro(const struct module *mod, bool after_init)
 		return;
 #endif
 
-	set_vm_flush_reset_perms(mod->core_layout.base);
-	set_vm_flush_reset_perms(mod->init_layout.base);
-	frob_text(&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);
+	module_set_memory(mod, MOD_TEXT, set_memory_ro);
+	module_set_memory(mod, MOD_INIT_TEXT, set_memory_ro);
+	module_set_memory(mod, MOD_RODATA, set_memory_ro);
+	module_set_memory(mod, MOD_INIT_RODATA, set_memory_ro);
 
 	if (after_init)
-		frob_ro_after_init(&mod->data_layout, set_memory_ro);
+		module_set_memory(mod, MOD_RO_AFTER_INIT, set_memory_ro);
 }
 
 void module_enable_nx(const struct module *mod)
@@ -115,11 +55,8 @@ void module_enable_nx(const struct module *mod)
 	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
 		return;
 
-	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);
+	for_class_mod_mem_type(type, data)
+		module_set_memory(mod, type, set_memory_nx);
 }
 
 int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,