[Qemu-devel] [PULL 14/32] tcg/arm: Return false on failure from patch_reloc

[Richard Henderson <richard.henderson@linaro.org>]

This does require an extra two checks within the slow paths
to replace the assert that we're moving.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/arm/tcg-target.inc.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/tcg/arm/tcg-target.inc.c b/tcg/arm/tcg-target.inc.c
index deefa20fbf..49f57d655e 100644
--- a/tcg/arm/tcg-target.inc.c
+++ b/tcg/arm/tcg-target.inc.c
@@ -187,10 +187,14 @@ static const uint8_t tcg_cond_to_arm_cond[] = {
     [TCG_COND_GTU] = COND_HI,
 };
 
-static inline void reloc_pc24(tcg_insn_unit *code_ptr, tcg_insn_unit *target)
+static inline bool reloc_pc24(tcg_insn_unit *code_ptr, tcg_insn_unit *target)
 {
     ptrdiff_t offset = (tcg_ptr_byte_diff(target, code_ptr) - 8) >> 2;
-    *code_ptr = (*code_ptr & ~0xffffff) | (offset & 0xffffff);
+    if (offset == sextract32(offset, 0, 24)) {
+        *code_ptr = (*code_ptr & ~0xffffff) | (offset & 0xffffff);
+        return true;
+    }
+    return false;
 }
 
 static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
@@ -199,7 +203,7 @@ static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
     tcg_debug_assert(addend == 0);
 
     if (type == R_ARM_PC24) {
-        reloc_pc24(code_ptr, (tcg_insn_unit *)value);
+        return reloc_pc24(code_ptr, (tcg_insn_unit *)value);
     } else if (type == R_ARM_PC13) {
         intptr_t diff = value - (uintptr_t)(code_ptr + 2);
         tcg_insn_unit insn = *code_ptr;
@@ -213,7 +217,11 @@ static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
         } else {
             int rd = extract32(insn, 12, 4);
             int rt = rd == TCG_REG_PC ? TCG_REG_TMP : rd;
-            assert(diff >= 0x1000 && diff < 0x100000);
+
+            if (diff < 0x1000 || diff >= 0x100000) {
+                return false;
+            }
+
             /* add rt, pc, #high */
             *code_ptr++ = ((insn & 0xf0000000) | (1 << 25) | ARITH_ADD
                            | (TCG_REG_PC << 16) | (rt << 12)
@@ -1372,7 +1380,8 @@ static void tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *lb)
     TCGMemOp opc = get_memop(oi);
     void *func;
 
-    reloc_pc24(lb->label_ptr[0], s->code_ptr);
+    bool ok = reloc_pc24(lb->label_ptr[0], s->code_ptr);
+    tcg_debug_assert(ok);
 
     argreg = tcg_out_arg_reg32(s, TCG_REG_R0, TCG_AREG0);
     if (TARGET_LONG_BITS == 64) {
@@ -1432,7 +1441,8 @@ static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *lb)
     TCGMemOpIdx oi = lb->oi;
     TCGMemOp opc = get_memop(oi);
 
-    reloc_pc24(lb->label_ptr[0], s->code_ptr);
+    bool ok = reloc_pc24(lb->label_ptr[0], s->code_ptr);
+    tcg_debug_assert(ok);
 
     argreg = TCG_REG_R0;
     argreg = tcg_out_arg_reg32(s, argreg, TCG_AREG0);
-- 
2.17.2