commit 3205cddff06f0b59c1de05f594992d96f7194da3
author Elliott Hughes <enh@google.com> Wed Jun 10 14:48:06 2020 -0700
committer Elliott Hughes <enh@google.com> Wed Jun 10 14:49:28 2020 -0700
tree 5bf325b5b1a0c0a69bcb2734ea55103e77d42b98
parent 79686ca145b5e54e3de4e409a82d72bdc7f22e88

linker: CHECK() or async_safe_fatal() rather than abort().

In particular, add the strerror() output if mprotect() fails.

Fix the CHECK macro so that you can make assertions involving operator%
without that being confused for a printf format specifier.

Bug: https://issuetracker.google.com/158645318
Test: treehugger
Change-Id: I6817f8ca5f094c52dc2c9067bfac90385a8743f5

libc/async_safe/include/async_safe/CHECK.h

diff --git a/libc/async_safe/include/async_safe/CHECK.h b/libc/async_safe/include/async_safe/CHECK.h
index bec89a3..46d460c 100644
--- a/libc/async_safe/include/async_safe/CHECK.h
+++ b/libc/async_safe/include/async_safe/CHECK.h
@@ -36,12 +36,12 @@
 
 // TODO: replace this with something more like <android-base/logging.h>'s family of macros.
 
-#define CHECK(predicate) \
-  do { \
-    if (!(predicate)) { \
-      async_safe_fatal("%s:%d: %s CHECK '" #predicate "' failed", \
-          __FILE__, __LINE__, __FUNCTION__); \
-    } \
-  } while(0)
+#define CHECK(predicate)                                                                \
+  do {                                                                                  \
+    if (!(predicate)) {                                                                 \
+      async_safe_fatal("%s:%d: %s CHECK '%s' failed", __FILE__, __LINE__, __FUNCTION__, \
+                       #predicate);                                                     \
+    }                                                                                   \
+  } while (0)
 
 __END_DECLS

linker/linker_block_allocator.cpp

diff --git a/linker/linker_block_allocator.cpp b/linker/linker_block_allocator.cpp
index 1e2f9a2..5b68b1d 100644
--- a/linker/linker_block_allocator.cpp
+++ b/linker/linker_block_allocator.cpp
@@ -27,12 +27,15 @@
  */
 
 #include "linker_block_allocator.h"
+
 #include <inttypes.h>
 #include <string.h>
 #include <sys/mman.h>
 #include <sys/prctl.h>
 #include <unistd.h>
 
+#include "linker_debug.h"
+
 static constexpr size_t kAllocateSize = PAGE_SIZE * 100;
 static_assert(kAllocateSize % PAGE_SIZE == 0, "Invalid kAllocateSize.");
 
@@ -88,16 +91,10 @@
   }
 
   LinkerBlockAllocatorPage* page = find_page(block);
-
-  if (page == nullptr) {
-    abort();
-  }
+  CHECK(page != nullptr);
 
   ssize_t offset = reinterpret_cast<uint8_t*>(block) - page->bytes;
-
-  if (offset % block_size_ != 0) {
-    abort();
-  }
+  CHECK((offset % block_size_) == 0);
 
   memset(block, 0, block_size_);
 
@@ -114,7 +111,7 @@
 void LinkerBlockAllocator::protect_all(int prot) {
   for (LinkerBlockAllocatorPage* page = page_list_; page != nullptr; page = page->next) {
     if (mprotect(page, kAllocateSize, prot) == -1) {
-      abort();
+      async_safe_fatal("mprotect(%p, %zu, %d) failed: %m", page, kAllocateSize, prot);
     }
   }
 }
@@ -125,10 +122,7 @@
 
   LinkerBlockAllocatorPage* page = reinterpret_cast<LinkerBlockAllocatorPage*>(
       mmap(nullptr, kAllocateSize, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0));
-
-  if (page == MAP_FAILED) {
-    abort(); // oom
-  }
+  CHECK(page != MAP_FAILED);
 
   prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, page, kAllocateSize, "linker_alloc");
 
@@ -143,9 +137,7 @@
 }
 
 LinkerBlockAllocatorPage* LinkerBlockAllocator::find_page(void* block) {
-  if (block == nullptr) {
-    abort();
-  }
+  CHECK(block != nullptr);
 
   LinkerBlockAllocatorPage* page = page_list_;
   while (page != nullptr) {
@@ -157,7 +149,7 @@
     page = page->next;
   }
 
-  abort();
+  async_safe_fatal("couldn't find page for %p", block);
 }
 
 void LinkerBlockAllocator::purge() {