commit 97c16f8dca0694abfcdda34f8e01f5e1e989120f
author Evgenii Stepanov <eugenis@google.com> Wed Aug 02 16:34:44 2017 -0700
committer Evgenii Stepanov <eugenis@google.com> Thu Aug 03 14:04:15 2017 -0700
tree ba62a11fcce7608e521e517ffd09f2a12b09c00c
parent bb36e9fae1f30c5673138c7f1a3ed6ac9b477f76

[cfi] Export __cfi_shadow_size.

__cfi_shadow_size returns the size of the CFI shadow mapping, or 0 if
CFI is not (yet) used in this process. This can be used to adjust
RLIMIT_AS setting.

Test: device bionic tests
Bug: 64293803
Change-Id: Icd7164f96aa7115b3585c21c0f68529cd2f07c11

libdl/libdl.arm.map

diff --git a/libdl/libdl.arm.map b/libdl/libdl.arm.map
index 292bd97..9fc9d23 100644
--- a/libdl/libdl.arm.map
+++ b/libdl/libdl.arm.map
@@ -36,6 +36,7 @@
 
 LIBC_OMR1 { # future
   global:
+    __cfi_shadow_size; # future
     __cfi_slowpath; # future
     __cfi_slowpath_diag; # future
 } LIBC_N;

libdl/libdl.arm64.map

diff --git a/libdl/libdl.arm64.map b/libdl/libdl.arm64.map
index 2fe2c7b..bde6cab 100644
--- a/libdl/libdl.arm64.map
+++ b/libdl/libdl.arm64.map
@@ -35,6 +35,7 @@
 
 LIBC_OMR1 { # future
   global:
+    __cfi_shadow_size; # future
     __cfi_slowpath; # future
     __cfi_slowpath_diag; # future
 } LIBC_N;

libdl/libdl.map.txt

diff --git a/libdl/libdl.map.txt b/libdl/libdl.map.txt
index 408d4dc..d1f4ab8 100644
--- a/libdl/libdl.map.txt
+++ b/libdl/libdl.map.txt
@@ -35,6 +35,7 @@
 
 LIBC_OMR1 { # future
   global:
+    __cfi_shadow_size; # future
     __cfi_slowpath; # future
     __cfi_slowpath_diag; # future
 } LIBC_N;

libdl/libdl.mips.map

diff --git a/libdl/libdl.mips.map b/libdl/libdl.mips.map
index 2fe2c7b..bde6cab 100644
--- a/libdl/libdl.mips.map
+++ b/libdl/libdl.mips.map
@@ -35,6 +35,7 @@
 
 LIBC_OMR1 { # future
   global:
+    __cfi_shadow_size; # future
     __cfi_slowpath; # future
     __cfi_slowpath_diag; # future
 } LIBC_N;

libdl/libdl.mips64.map

diff --git a/libdl/libdl.mips64.map b/libdl/libdl.mips64.map
index 2fe2c7b..bde6cab 100644
--- a/libdl/libdl.mips64.map
+++ b/libdl/libdl.mips64.map
@@ -35,6 +35,7 @@
 
 LIBC_OMR1 { # future
   global:
+    __cfi_shadow_size; # future
     __cfi_slowpath; # future
     __cfi_slowpath_diag; # future
 } LIBC_N;

libdl/libdl.x86.map

diff --git a/libdl/libdl.x86.map b/libdl/libdl.x86.map
index 2fe2c7b..bde6cab 100644
--- a/libdl/libdl.x86.map
+++ b/libdl/libdl.x86.map
@@ -35,6 +35,7 @@
 
 LIBC_OMR1 { # future
   global:
+    __cfi_shadow_size; # future
     __cfi_slowpath; # future
     __cfi_slowpath_diag; # future
 } LIBC_N;

libdl/libdl.x86_64.map

diff --git a/libdl/libdl.x86_64.map b/libdl/libdl.x86_64.map
index 2fe2c7b..bde6cab 100644
--- a/libdl/libdl.x86_64.map
+++ b/libdl/libdl.x86_64.map
@@ -35,6 +35,7 @@
 
 LIBC_OMR1 { # future
   global:
+    __cfi_shadow_size; # future
     __cfi_slowpath; # future
     __cfi_slowpath_diag; # future
 } LIBC_N;

libdl/libdl_cfi.cpp

diff --git a/libdl/libdl_cfi.cpp b/libdl/libdl_cfi.cpp
index 8458564..483364f 100644
--- a/libdl/libdl_cfi.cpp
+++ b/libdl/libdl_cfi.cpp
@@ -38,6 +38,11 @@
   return &shadow_base_storage.v;
 }
 
+// Returns the size of the CFI shadow mapping, or 0 if CFI is not (yet) used in this process.
+extern "C" size_t __cfi_shadow_size() {
+  return shadow_base_storage.v != 0 ? CFIShadow::kShadowSize : 0;
+}
+
 static uint16_t shadow_load(void* p) {
   uintptr_t addr = reinterpret_cast<uintptr_t>(p);
   uintptr_t ofs = CFIShadow::MemToShadowOffset(addr);

tests/cfi_test.cpp

diff --git a/tests/cfi_test.cpp b/tests/cfi_test.cpp
index 5e627a7..088dda6 100644
--- a/tests/cfi_test.cpp
+++ b/tests/cfi_test.cpp
@@ -26,6 +26,7 @@
 extern "C" {
 void __cfi_slowpath(uint64_t CallSiteTypeId, void* Ptr);
 void __cfi_slowpath_diag(uint64_t CallSiteTypeId, void* Ptr, void* DiagData);
+size_t __cfi_shadow_size();
 }
 
 static void f() {}
@@ -36,6 +37,8 @@
   handle = dlopen("libcfi-test.so", RTLD_NOW | RTLD_LOCAL);
   ASSERT_TRUE(handle != nullptr) << dlerror();
 
+  EXPECT_NE(0U, __cfi_shadow_size());
+
 #define SYM(type, name) auto name = reinterpret_cast<type>(dlsym(handle, #name))
   SYM(int (*)(), get_count);
   SYM(uint64_t(*)(), get_last_type_id);