ARM: fixup SMP alternatives in modules

With certain configurations, we inline the unlock functions in modules,
which results in SMP alternatives being created in modules.  We need to
fix those up when loading a module to prevent undefined instruction
faults.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 47 insertions, 13 deletions

diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index c0225da3fb21..f06ff9feb0db 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -391,6 +391,7 @@ ENDPROC(__turn_mmu_on)
 
 
 #ifdef CONFIG_SMP_ON_UP
+        __INIT
 __fixup_smp:
         and     r3, r9, #0x000f0000     @ architecture version
         teq     r3, #0x000f0000         @ CPU ID supported?
@@ -415,18 +416,7 @@ __fixup_smp_on_up:
         sub     r3, r0, r3
         add     r4, r4, r3
         add     r5, r5, r3
-2:      cmp     r4, r5
-        movhs   pc, lr
-        ldmia   r4!, {r0, r6}
- ARM(   str     r6, [r0, r3]    )
- THUMB( add     r0, r0, r3      )
-#ifdef __ARMEB__
- THUMB( mov     r6, r6, ror #16 )       @ Convert word order for big-endian.
-#endif
- THUMB( strh    r6, [r0], #2    )       @ For Thumb-2, store as two halfwords
- THUMB( mov     r6, r6, lsr #16 )       @ to be robust against misaligned r3.
- THUMB( strh    r6, [r0]        )
-        b       2b
+        b       __do_fixup_smp_on_up
 ENDPROC(__fixup_smp)
 
         .align
@@ -440,7 +430,31 @@ smp_on_up:
         ALT_SMP(.long   1)
         ALT_UP(.long    0)
         .popsection
+#endif
 
+        .text
+__do_fixup_smp_on_up:
+        cmp     r4, r5
+        movhs   pc, lr
+        ldmia   r4!, {r0, r6}
+ ARM(   str     r6, [r0, r3]    )
+ THUMB( add     r0, r0, r3      )
+#ifdef __ARMEB__
+ THUMB( mov     r6, r6, ror #16 )       @ Convert word order for big-endian.
 #endif
+ THUMB( strh    r6, [r0], #2    )       @ For Thumb-2, store as two halfwords
+ THUMB( mov     r6, r6, lsr #16 )       @ to be robust against misaligned r3.
+ THUMB( strh    r6, [r0]        )
+        b       __do_fixup_smp_on_up
+ENDPROC(__do_fixup_smp_on_up)
+
+ENTRY(fixup_smp)
+        stmfd   sp!, {r4 - r6, lr}
+        mov     r4, r0
+        add     r5, r0, r1
+        mov     r3, #0
+        bl      __do_fixup_smp_on_up
+        ldmfd   sp!, {r4 - r6, pc}
+ENDPROC(fixup_smp)
 
 #include "head-common.S"
diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index 2cfe8161b478..6d4105e6872f 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -22,6 +22,7 @@
 
 #include <asm/pgtable.h>
 #include <asm/sections.h>
+#include <asm/smp_plat.h>
 #include <asm/unwind.h>
 
 #ifdef CONFIG_XIP_KERNEL
@@ -268,12 +269,28 @@ struct mod_unwind_map {
         const Elf_Shdr *txt_sec;
 };
 
+static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
+        const Elf_Shdr *sechdrs, const char *name)
+{
+        const Elf_Shdr *s, *se;
+        const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+
+        for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
+                if (strcmp(name, secstrs + s->sh_name) == 0)
+                        return s;
+
+        return NULL;
+}
+
+extern void fixup_smp(const void *, unsigned long);
+
 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
                     struct module *mod)
 {
+        const Elf_Shdr * __maybe_unused s = NULL;
 #ifdef CONFIG_ARM_UNWIND
         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
-        const Elf_Shdr *s, *sechdrs_end = sechdrs + hdr->e_shnum;
+        const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
         struct mod_unwind_map maps[ARM_SEC_MAX];
         int i;
 
@@ -315,6 +332,9 @@ int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
                                                  maps[i].txt_sec->sh_addr,
                                                  maps[i].txt_sec->sh_size);
 #endif
+        s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
+        if (s && !is_smp())
+                fixup_smp((void *)s->sh_addr, s->sh_size);
         return 0;
 }