ARM: 8219/1: handle interworking and out-of-range relocations separately

Currently, interworking calls on module boundaries are not supported,
and are handled by the same error handling code path as non-interworking
calls whose targets are simply out of range.

Before modifying the handling of those out-of-range jump and call
relocations in a subsequent patch, move the handling of interworking
restrictions out of it.

Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 24 insertions, 14 deletions

diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index 2e11961f65ae..af791f4a6205 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -98,14 +98,19 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
                 case R_ARM_PC24:
                 case R_ARM_CALL:
                 case R_ARM_JUMP24:
+                        if (sym->st_value & 3) {
+                                pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (ARM -> Thumb)\n",
+                                       module->name, relindex, i, symname);
+                                return -ENOEXEC;
+                        }
+
                         offset = __mem_to_opcode_arm(*(u32 *)loc);
                         offset = (offset & 0x00ffffff) << 2;
                         if (offset & 0x02000000)
                                 offset -= 0x04000000;
 
                         offset += sym->st_value - loc;
-                        if (offset & 3 ||
-                            offset <= (s32)0xfe000000 ||
+                        if (offset <= (s32)0xfe000000 ||
                             offset >= (s32)0x02000000) {
                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
                                        module->name, relindex, i, symname,
@@ -155,6 +160,22 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
 #ifdef CONFIG_THUMB2_KERNEL
                 case R_ARM_THM_CALL:
                 case R_ARM_THM_JUMP24:
+                        /*
+                         * For function symbols, only Thumb addresses are
+                         * allowed (no interworking).
+                         *
+                         * For non-function symbols, the destination
+                         * has no specific ARM/Thumb disposition, so
+                         * the branch is resolved under the assumption
+                         * that interworking is not required.
+                         */
+                        if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
+                            !(sym->st_value & 1)) {
+                                pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (Thumb -> ARM)\n",
+                                       module->name, relindex, i, symname);
+                                return -ENOEXEC;
+                        }
+
                         upper = __mem_to_opcode_thumb16(*(u16 *)loc);
                         lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
 
@@ -182,18 +203,7 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
                                 offset -= 0x02000000;
                         offset += sym->st_value - loc;
 
-                        /*
-                         * For function symbols, only Thumb addresses are
-                         * allowed (no interworking).
-                         *
-                         * For non-function symbols, the destination
-                         * has no specific ARM/Thumb disposition, so
-                         * the branch is resolved under the assumption
-                         * that interworking is not required.
-                         */
-                        if ((ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
-                                !(offset & 1)) ||
-                            offset <= (s32)0xff000000 ||
+                        if (offset <= (s32)0xff000000 ||
                             offset >= (s32)0x01000000) {
                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
                                        module->name, relindex, i, symname,