ARM: 6189/1: Add support for the MOVW/MOVT relocations in Thumb-2

The patch adds handling case for the R_ARM_THM_MOVW_ABS_NC and
R_ARM_THM_MOVT_ABS relocations in arch/arm/kernel/module.c. Such
relocations may appear in Thumb-2 compiled kernel modules.

Reported-by: Kyungmin Park <kmpark@infradead.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 32 insertions, 0 deletions

diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index c628bdf6c430..ae3c80453a09 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -237,6 +237,38 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
                         lower = *(u16 *)(loc + 2);
                         break;
 
+                case R_ARM_THM_MOVW_ABS_NC:
+                case R_ARM_THM_MOVT_ABS:
+                        upper = *(u16 *)loc;
+                        lower = *(u16 *)(loc + 2);
+
+                        /*
+                         * MOVT/MOVW instructions encoding in Thumb-2:
+                         *
+                         * i    = upper[10]
+                         * imm4 = upper[3:0]
+                         * imm3 = lower[14:12]
+                         * imm8 = lower[7:0]
+                         *
+                         * imm16 = imm4:i:imm3:imm8
+                         */
+                        offset = ((upper & 0x000f) << 12) |
+                                ((upper & 0x0400) << 1) |
+                                ((lower & 0x7000) >> 4) | (lower & 0x00ff);
+                        offset = (offset ^ 0x8000) - 0x8000;
+                        offset += sym->st_value;
+
+                        if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
+                                offset >>= 16;
+
+                        *(u16 *)loc = (u16)((upper & 0xfbf0) |
+                                            ((offset & 0xf000) >> 12) |
+                                            ((offset & 0x0800) >> 1));
+                        *(u16 *)(loc + 2) = (u16)((lower & 0x8f00) |
+                                                  ((offset & 0x0700) << 4) |
+                                                  (offset & 0x00ff));
+                        break;
+
                 default:
                         printk(KERN_ERR "%s: unknown relocation: %u\n",
                                module->name, ELF32_R_TYPE(rel->r_info));