Le 03/02/2022 à 00:48, Luis Chamberlain a écrit :

On Sat, Jan 29, 2022 at 05:02:07PM +0000, Christophe Leroy wrote:

quoted

diff --git a/kernel/module.c b/kernel/module.c
index 163e32e39064..11f51e17fb9f 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),

@@ -2451,7 +2454,10 @@ 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);

Huh why is this branching here, given you just used mod->data_layout in
all other areas?

The module text remains in core_layout, so the text section still needs 
core_layout. In the masks[][] table, it corresponds to the first line, 
which has flag  SHF_EXECINSTR. In the loop that's when 'm' is 0.

In the following switch/case, case 0 still uses core_layout.

quoted

@@ -3468,6 +3474,8 @@ 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;
  

Likewise here.

Same here, the section with flag SHF_EXECINSTR is a text section, it 
stays in core_layout.

Christophe