[POWERPC] Support feature fixups in modules

This patch adds support for feature fixups in modules. This involves
adding support for R_PPC64_REL64 relocs to the 64 bits module loader.
It also modifies modpost.c to ignore the powerpc fixup sections (or it
would warn when used in .init.text).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>

3 files changed, 71 insertions, 19 deletions

diff --git a/arch/powerpc/kernel/module_32.c b/arch/powerpc/kernel/module_32.c
index 92f4e5f64f02..e2c3c6a85f33 100644
--- a/arch/powerpc/kernel/module_32.c
+++ b/arch/powerpc/kernel/module_32.c
@@ -24,6 +24,8 @@
 #include <linux/kernel.h>
 #include <linux/cache.h>
 
+#include "setup.h"
+
 #if 0
 #define DEBUGP printk
 #else
@@ -269,33 +271,50 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
         return 0;
 }
 
+static const Elf_Shdr *find_section(const Elf_Ehdr *hdr,
+                                    const Elf_Shdr *sechdrs,
+                                    const char *name)
+{
+        char *secstrings;
+        unsigned int i;
+
+        secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+        for (i = 1; i < hdr->e_shnum; i++)
+                if (strcmp(secstrings+sechdrs[i].sh_name, name) == 0)
+                        return &sechdrs[i];
+        return NULL;
+}
+
 int module_finalize(const Elf_Ehdr *hdr,
                     const Elf_Shdr *sechdrs,
                     struct module *me)
 {
-        char *secstrings;
-        unsigned int i;
+        const Elf_Shdr *sect;
 
         me->arch.bug_table = NULL;
         me->arch.num_bugs = 0;
 
         /* Find the __bug_table section, if present */
-        secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
-        for (i = 1; i < hdr->e_shnum; i++) {
-                if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table"))
-                        continue;
-                me->arch.bug_table = (void *) sechdrs[i].sh_addr;
-                me->arch.num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);
-                break;
+        sect = find_section(hdr, sechdrs, "__bug_table");
+        if (sect != NULL) {
+                me->arch.bug_table = (void *) sect->sh_addr;
+                me->arch.num_bugs = sect->sh_size / sizeof(struct bug_entry);
         }
 
-        /*
+        /*
          * Strictly speaking this should have a spinlock to protect against
          * traversals, but since we only traverse on BUG()s, a spinlock
          * could potentially lead to deadlock and thus be counter-productive.
          */
         list_add(&me->arch.bug_list, &module_bug_list);
 
+        /* Apply feature fixups */
+        sect = find_section(hdr, sechdrs, "__ftr_fixup");
+        if (sect != NULL)
+                do_feature_fixups(cur_cpu_spec->cpu_features,
+                                  (void *)sect->sh_addr,
+                                  (void *)sect->sh_addr + sect->sh_size);
+
         return 0;
 }
 
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index ba34001fca8e..8dd1f0aae5d6 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -22,6 +22,9 @@
 #include <linux/vmalloc.h>
 #include <asm/module.h>
 #include <asm/uaccess.h>
+#include <asm/firmware.h>
+
+#include "setup.h"
 
 /* FIXME: We don't do .init separately.  To do this, we'd need to have
    a separate r2 value in the init and core section, and stub between
@@ -400,6 +403,11 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
                                 | (value & 0x03fffffc);
                         break;
 
+                case R_PPC64_REL64:
+                        /* 64 bits relative (used by features fixups) */
+                        *location = value - (unsigned long)location;
+                        break;
+
                 default:
                         printk("%s: Unknown ADD relocation: %lu\n",
                                me->name,
@@ -413,23 +421,33 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
 
 LIST_HEAD(module_bug_list);
 
-int module_finalize(const Elf_Ehdr *hdr,
-                const Elf_Shdr *sechdrs, struct module *me)
+static const Elf_Shdr *find_section(const Elf_Ehdr *hdr,
+                                    const Elf_Shdr *sechdrs,
+                                    const char *name)
 {
         char *secstrings;
         unsigned int i;
 
+        secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+        for (i = 1; i < hdr->e_shnum; i++)
+                if (strcmp(secstrings+sechdrs[i].sh_name, name) == 0)
+                        return &sechdrs[i];
+        return NULL;
+}
+
+int module_finalize(const Elf_Ehdr *hdr,
+                const Elf_Shdr *sechdrs, struct module *me)
+{
+        const Elf_Shdr *sect;
+
         me->arch.bug_table = NULL;
         me->arch.num_bugs = 0;
 
         /* Find the __bug_table section, if present */
-        secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
-        for (i = 1; i < hdr->e_shnum; i++) {
-                if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table"))
-                        continue;
-                me->arch.bug_table = (void *) sechdrs[i].sh_addr;
-                me->arch.num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);
-                break;
+        sect = find_section(hdr, sechdrs, "__bug_table");
+        if (sect != NULL) {
+                me->arch.bug_table = (void *) sect->sh_addr;
+                me->arch.num_bugs = sect->sh_size / sizeof(struct bug_entry);
         }
 
         /*
@@ -439,6 +457,19 @@ int module_finalize(const Elf_Ehdr *hdr,
          */
         list_add(&me->arch.bug_list, &module_bug_list);
 
+        /* Apply feature fixups */
+        sect = find_section(hdr, sechdrs, "__ftr_fixup");
+        if (sect != NULL)
+                do_feature_fixups(cur_cpu_spec->cpu_features,
+                                  (void *)sect->sh_addr,
+                                  (void *)sect->sh_addr + sect->sh_size);
+
+        sect = find_section(hdr, sechdrs, "__fw_ftr_fixup");
+        if (sect != NULL)
+                do_feature_fixups(powerpc_firmware_features,
+                                  (void *)sect->sh_addr,
+                                  (void *)sect->sh_addr + sect->sh_size);
+
         return 0;
 }
 
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 41277963f47a..2e1141623147 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -921,6 +921,8 @@ static int init_section_ref_ok(const char *name)
                 ".fixup",
                 ".smp_locks",
                 ".plt",  /* seen on ARCH=um build on x86_64. Harmless */
+                "__ftr_fixup",          /* powerpc cpu feature fixup */
+                "__fw_ftr_fixup",       /* powerpc firmware feature fixup */
                 NULL
         };
         /* Start of section names */