commit 00d087c629185f8237488aaa992ebbf491841a68
author Evgenii Stepanov <eugenis@google.com> Fri Aug 31 14:27:32 2018 -0700
committer Evgenii Stepanov <eugenis@google.com> Fri Aug 31 15:02:12 2018 -0700
tree 158a86c72599fbf10d1400053583249844d415d6
parent 23cfc34790f171bc05f149fc5f7bde3102f169af

(arm64) Extend branch range in __memcpy_chk.

Conditional branch has limited range (1MB) and can not be extended by
the linker. The current distance (in walleye build) is 500KB, about
half of the maximum. HWASan pushes it over the limit.

Replace conditional branch with regular branch, which has longer
range (26 vs 19 bits offset) and can be extended in the linker if
needed.

Bug: 112437884
Bug: 12231437
Test: SANITIZE_TARGET=hwaddress

Change-Id: Idc083fb557ab3a859541beb009809992406a6703

libc/arch-arm64/generic/bionic/__memcpy_chk.S

diff --git a/libc/arch-arm64/generic/bionic/__memcpy_chk.S b/libc/arch-arm64/generic/bionic/__memcpy_chk.S
index 4217775..a6eeca4 100644
--- a/libc/arch-arm64/generic/bionic/__memcpy_chk.S
+++ b/libc/arch-arm64/generic/bionic/__memcpy_chk.S
@@ -30,8 +30,11 @@
 
 ENTRY(__memcpy_chk)
   cmp x2, x3
-  bls memcpy
+  // Direct b.ls memcpy may not have enough range
+  b.hi .L_memcpy_chk_fail
+  b memcpy
 
+.L_memcpy_chk_fail:
   // Preserve for accurate backtrace.
   stp x29, x30, [sp, -16]!
   .cfi_def_cfa_offset 16