commit 8e5fc5b0379fa659d5def8582a1991d6d47cdd13
author Elliott Hughes <enh@google.com> Thu Sep 03 12:31:07 2020 -0700
committer Elliott Hughes <enh@google.com> Tue Sep 08 09:27:02 2020 -0700
tree 1b338acf9363948520c42f27c2766584a534d1dc
parent 7e0816a0a48d0dd96b4ffad5abd1506d478cbe67

NGREG != ELF_NGREG.

Except they are the same on arm32/arm64, so we hadn't really noticed. x86
and x86-64 are quite different though, presumably by historical accident.

Fix the definitions and add some static asserts.

Bug: https://github.com/android/ndk/issues/1347
Test: treehugger
Change-Id: Ic27b172066cf3443749463b9b73c912d204f9516

libc/include/sys/procfs.h

diff --git a/libc/include/sys/procfs.h b/libc/include/sys/procfs.h
index 75a1e98..a082e97 100644
--- a/libc/include/sys/procfs.h
+++ b/libc/include/sys/procfs.h
@@ -26,16 +26,24 @@
  * SUCH DAMAGE.
  */
 
-#ifndef _SYS_PROCFS_H_
-#define _SYS_PROCFS_H_
+#pragma once
 
 #include <sys/cdefs.h>
+#include <sys/ptrace.h>
 #include <sys/ucontext.h>
 
 __BEGIN_DECLS
 
+#if defined(__arm__)
+#define ELF_NGREG (sizeof(struct user_regs) / sizeof(elf_greg_t))
+#elif defined(__aarch64__)
+#define ELF_NGREG (sizeof(struct user_pt_regs) / sizeof(elf_greg_t))
+#else
+#define ELF_NGREG (sizeof(struct user_regs_struct) / sizeof(elf_greg_t))
+#endif
+
 typedef unsigned long elf_greg_t;
-typedef elf_greg_t elf_gregset_t[NGREG];
+typedef elf_greg_t elf_gregset_t[ELF_NGREG];
 
 typedef fpregset_t elf_fpregset_t;
 
@@ -58,5 +66,3 @@
 #define ELF_PRARGSZ 80
 
 __END_DECLS
-
-#endif

tests/sys_procfs_test.cpp

diff --git a/tests/sys_procfs_test.cpp b/tests/sys_procfs_test.cpp
index 8054869..5e0a0b0 100644
--- a/tests/sys_procfs_test.cpp
+++ b/tests/sys_procfs_test.cpp
@@ -18,7 +18,7 @@
 
 #include <sys/procfs.h>
 
-TEST(sys_procfs, smoke) {
+TEST(sys_procfs, types) {
   elf_greg_t reg;
   memset(&reg, 0, sizeof(reg));
 
@@ -37,3 +37,16 @@
   static_assert(sizeof(prgregset_t) == sizeof(elf_gregset_t), "");
   static_assert(sizeof(prfpregset_t) == sizeof(elf_fpregset_t), "");
 }
+
+TEST(sys_procfs, constants) {
+  // NGREG != ELF_NGREG (https://github.com/android/ndk/issues/1347)
+  static_assert(sizeof(gregset_t) / sizeof(greg_t) == NGREG);
+
+#if defined(__arm__)
+  static_assert(sizeof(user_regs) / sizeof(elf_greg_t) == ELF_NGREG);
+#elif defined(__aarch64__)
+  static_assert(sizeof(user_pt_regs) / sizeof(elf_greg_t) == ELF_NGREG);
+#else
+  static_assert(sizeof(user_regs_struct) / sizeof(elf_greg_t) == ELF_NGREG);
+#endif
+}