From 33b51e87e1d89c6e1bd723942871b15ae1b9d0f0 Mon Sep 17 00:00:00 2001 From: Pavel Labath Date: Mon, 29 Jun 2015 09:18:17 +0000 Subject: [PATCH] [linux] Use cmake to detect support process_vm_readv (bug #23918) Summary: Some old linux versions do not have process_vm_readv function defined. Even older versions do not have even the __NR_process_vm_readv syscall number. We use cmake to detect these situations and fallback appropriately: in the first case, we can issue the syscall manually, while it the latter case, we need to drop fast memory read support completely. Test Plan: linux test suite passes Reviewers: ovyalov, Eugene.Zelenko Subscribers: tberghammer, lldb-commits Differential Revision: http://reviews.llvm.org/D10727 llvm-svn: 240927 --- lldb/cmake/modules/LLDBConfig.cmake | 24 ++++++++++++++++++++++ lldb/include/lldb/Host/linux/Uio.h | 4 ++-- lldb/source/Host/CMakeLists.txt | 2 ++ lldb/source/Host/android/LibcGlue.cpp | 9 --------- lldb/source/Host/linux/LibcGlue.cpp | 29 +++++++++++++++++++++++++++ 5 files changed, 57 insertions(+), 11 deletions(-) create mode 100644 lldb/source/Host/linux/LibcGlue.cpp diff --git a/lldb/cmake/modules/LLDBConfig.cmake b/lldb/cmake/modules/LLDBConfig.cmake index cea2f9af4899..4f6b4d60eb4c 100644 --- a/lldb/cmake/modules/LLDBConfig.cmake +++ b/lldb/cmake/modules/LLDBConfig.cmake @@ -248,3 +248,27 @@ if(NOT LLDB_REQUIRES_RTTI) endif() set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${LLDB_COMPILE_FLAGS}") + +if (CMAKE_SYSTEM_NAME MATCHES "Linux") + # Check for syscall used by lldb-server on linux. + # If these are not found, it will fall back to ptrace (slow) for memory reads. + check_cxx_source_compiles(" + #include + int main() { process_vm_readv(0, nullptr, 0, nullptr, 0, 0); return 0; }" + HAVE_PROCESS_VM_READV) + + if (HAVE_PROCESS_VM_READV) + add_definitions(-DHAVE_PROCESS_VM_READV) + else() + # If we don't have the syscall wrapper function, but we know the syscall number, we can + # still issue the syscall manually + check_cxx_source_compiles(" + #include + int main() { return __NR_process_vm_readv; }" + HAVE_NR_PROCESS_VM_READV) + + if (HAVE_NR_PROCESS_VM_READV) + add_definitions(-DHAVE_NR_PROCESS_VM_READV) + endif() + endif() +endif() diff --git a/lldb/include/lldb/Host/linux/Uio.h b/lldb/include/lldb/Host/linux/Uio.h index 5f2be074f540..08894c0a2ca8 100644 --- a/lldb/include/lldb/Host/linux/Uio.h +++ b/lldb/include/lldb/Host/linux/Uio.h @@ -12,8 +12,8 @@ #include -// Android does not define the process_vm_readv wrapper -#ifdef __ANDROID_NDK__ +// We shall provide our own implementation of process_vm_readv if it is not present +#ifndef HAVE_PROCESS_VM_READV ssize_t process_vm_readv(::pid_t pid, const struct iovec *local_iov, unsigned long liovcnt, const struct iovec *remote_iov, unsigned long riovcnt, diff --git a/lldb/source/Host/CMakeLists.txt b/lldb/source/Host/CMakeLists.txt index 0a005af18d75..4d6e2e08823d 100644 --- a/lldb/source/Host/CMakeLists.txt +++ b/lldb/source/Host/CMakeLists.txt @@ -110,6 +110,7 @@ else() linux/Host.cpp linux/HostInfoLinux.cpp linux/HostThreadLinux.cpp + linux/LibcGlue.cpp linux/ThisThread.cpp ) else() @@ -117,6 +118,7 @@ else() linux/Host.cpp linux/HostInfoLinux.cpp linux/HostThreadLinux.cpp + linux/LibcGlue.cpp linux/ThisThread.cpp ) endif() diff --git a/lldb/source/Host/android/LibcGlue.cpp b/lldb/source/Host/android/LibcGlue.cpp index d127d6b01ad9..3842fb6c2a8e 100644 --- a/lldb/source/Host/android/LibcGlue.cpp +++ b/lldb/source/Host/android/LibcGlue.cpp @@ -12,7 +12,6 @@ #include #include -#include #if __ANDROID_API__ < 21 @@ -39,11 +38,3 @@ int posix_openpt(int flags) } #endif - -ssize_t process_vm_readv(::pid_t pid, - const struct iovec *local_iov, unsigned long liovcnt, - const struct iovec *remote_iov, unsigned long riovcnt, - unsigned long flags) -{ - return syscall(__NR_process_vm_readv, pid, local_iov, liovcnt, remote_iov, riovcnt, flags); -} diff --git a/lldb/source/Host/linux/LibcGlue.cpp b/lldb/source/Host/linux/LibcGlue.cpp new file mode 100644 index 000000000000..6e07134971d8 --- /dev/null +++ b/lldb/source/Host/linux/LibcGlue.cpp @@ -0,0 +1,29 @@ +//===-- LibcGlue.cpp --------------------------------------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +// This file adds functions missing from libc on older versions of linux + +#include +#include +#include + +#ifndef HAVE_PROCESS_VM_READV // If the syscall wrapper is not available, provide one. +ssize_t process_vm_readv(::pid_t pid, + const struct iovec *local_iov, unsigned long liovcnt, + const struct iovec *remote_iov, unsigned long riovcnt, + unsigned long flags) +{ +#ifdef HAVE_NR_PROCESS_VM_READV // If we have the syscall number, we can issue the syscall ourselves. + return syscall(__NR_process_vm_readv, pid, local_iov, liovcnt, remote_iov, riovcnt, flags); +#else // If not, let's pretend the syscall is not present. + errno = ENOSYS; + return -1; +#endif +} +#endif