Annotate IA-32's SyscallAsm implementation with CFI directives

This is necessary so that glibc's backtrace() routine can properly unwind
the stack when called within a Trap handler triggered by Syscall::Call().
Otherwise the .eh_frame data will mislead backtrace() into thinking %ebp is
still valid, when we've actually clobbered it with a syscall parameter.

This allows us to also enable the InvalidSyscall BPF tests on IA-32.

BUG=399396

Review URL: https://codereview.chromium.org/430353002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@286959 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 8 insertions, 11 deletions

diff --git a/sandbox/linux/seccomp-bpf-helpers/baseline_policy_unittest.cc b/sandbox/linux/seccomp-bpf-helpers/baseline_policy_unittest.cc
index fdcb232..d1899c3 100644
--- a/sandbox/linux/seccomp-bpf-helpers/baseline_policy_unittest.cc
+++ b/sandbox/linux/seccomp-bpf-helpers/baseline_policy_unittest.cc
@@ -209,15 +209,12 @@ BPF_TEST_C(BaselinePolicy, EPERM_getcwd, BaselinePolicy) {
   BPF_ASSERT_EQ(EPERM, errno);
 }
 
-// TODO(mdempsky): Enable on IA-32 after fixing crbug.com/399396.
-#if !defined(__i386__)
 BPF_DEATH_TEST_C(BaselinePolicy,
                  SIGSYS_InvalidSyscall,
                  DEATH_SEGV_MESSAGE(GetErrorMessageContentForTests()),
                  BaselinePolicy) {
   Syscall::InvalidCall();
 }
-#endif
 
 // A failing test using this macro could be problematic since we perform
 // system calls by passing "0" as every argument.
diff --git a/sandbox/linux/seccomp-bpf/syscall.cc b/sandbox/linux/seccomp-bpf/syscall.cc
index eacaabd..b0a41b0 100644
--- a/sandbox/linux/seccomp-bpf/syscall.cc
+++ b/sandbox/linux/seccomp-bpf/syscall.cc
@@ -59,10 +59,10 @@ asm(// We need to be able to tell the kernel exactly where we made a
     // that are used internally (e.g. %ebx for position-independent
     // code, and %ebp for the frame pointer), and as we need to keep at
     // least a few registers available for the register allocator.
-    "1:push %esi; .cfi_adjust_cfa_offset 4\n"
-    "push %edi; .cfi_adjust_cfa_offset 4\n"
-    "push %ebx; .cfi_adjust_cfa_offset 4\n"
-    "push %ebp; .cfi_adjust_cfa_offset 4\n"
+    "1:push %esi; .cfi_adjust_cfa_offset 4; .cfi_rel_offset esi, 0\n"
+    "push %edi; .cfi_adjust_cfa_offset 4; .cfi_rel_offset edi, 0\n"
+    "push %ebx; .cfi_adjust_cfa_offset 4; .cfi_rel_offset ebx, 0\n"
+    "push %ebp; .cfi_adjust_cfa_offset 4; .cfi_rel_offset ebp, 0\n"
     // Copy entries from the array holding the arguments into the
     // correct CPU registers.
     "movl  0(%edi), %ebx\n"
@@ -77,10 +77,10 @@ asm(// We need to be able to tell the kernel exactly where we made a
     "2:"
     // Restore any clobbered registers that we didn't declare to the
     // compiler.
-    "pop  %ebp; .cfi_adjust_cfa_offset -4\n"
-    "pop  %ebx; .cfi_adjust_cfa_offset -4\n"
-    "pop  %edi; .cfi_adjust_cfa_offset -4\n"
-    "pop  %esi; .cfi_adjust_cfa_offset -4\n"
+    "pop  %ebp; .cfi_restore ebp; .cfi_adjust_cfa_offset -4\n"
+    "pop  %ebx; .cfi_restore ebx; .cfi_adjust_cfa_offset -4\n"
+    "pop  %edi; .cfi_restore edi; .cfi_adjust_cfa_offset -4\n"
+    "pop  %esi; .cfi_restore esi; .cfi_adjust_cfa_offset -4\n"
     "ret\n"
     ".cfi_endproc\n"
     "9:.size SyscallAsm, 9b-SyscallAsm\n"