Fix R_ARM_CALL when target fonction is Thumb

With R_ARM_CALL, if target function is to be entered in Thumb mode, the
relocation is supposed to transform bl in blx. This is not the case
actually so this commit is there to fix it.

1 files changed, 12 insertions, 4 deletions

diff --git a/tccelf.c b/tccelf.c
index 5e1a64e..7943763 100644
--- a/tccelf.c
+++ b/tccelf.c
@@ -601,22 +601,30 @@ ST_FUNC void relocate_section(TCCState *s1, Section *s)
         case R_ARM_JUMP24:
         case R_ARM_PLT32:
             {
-                int x;
+                int x, is_thumb, is_call, h;
                 x = (*(int *)ptr)&0xffffff;
                 (*(int *)ptr) &= 0xff000000;
                 if (x & 0x800000)
                     x -= 0x1000000;
-                x *= 4;
-                x += val - addr;
+                x <<= 2;
+                is_thumb = val & 1;
+                is_call = (type == R_ARM_CALL);
+                x += (val & -2) - addr;
+                h = x & 2;
 #ifndef TCC_TARGET_PE
                 if((x & 3) != 0 || x >= 0x4000000 || x < -0x4000000)
                     if (s1->output_type == TCC_OUTPUT_MEMORY)
                         x += add_jmp_table(s1, val) - val; /* add veneer */
 #endif
                 if((x & 3) != 0 || x >= 0x4000000 || x < -0x4000000)
-                    tcc_error("can't relocate value at %x",addr);
+                    if (!(h && is_call && is_thumb))
+                        tcc_error("can't relocate value at %x",addr);
                 x >>= 2;
                 x &= 0xffffff;
+                if (is_call && is_thumb) {
+                    x |= h << 24;
+                    (*(int *)ptr) = 0xfa << 24; /* bl -> blx */
+                }
                 (*(int *)ptr) |= x;
             }
             break;