i#1973 musl: fix build on musl libc

CMakeLists.txt

@@ -187,6 +187,27 @@ if (APPLE)
   set(OLDEST_OSX_SUPPPORTED "11.7")
 elseif (UNIX)
   set(LINUX 1)
+
+  # Identify whether building with (and targeting) musl libc with ldd. This
+  # assumes a native build. For cross compiling, a musl build could be forced
+  # by DR_TARGET_MUSL.
+  find_program(LDD ldd DOC "util for examing shared object dependency")
+  if (NOT LDD)
+    message(STATUS "Unable to find ldd: assume glibc")
+  else ()
+    execute_process(COMMAND ${LDD}
+      RESULT_VARIABLE ldd_result
+      ERROR_VARIABLE ldd_err
+      OUTPUT_VARIABLE ldd_out)
+      if (ldd_err MATCHES "^musl libc")
+        set(MUSL 1)
+      endif ()
+  endif ()
+
+  option(DR_TARGET_MUSL "Target musl libc" OFF)
+  if (DR_TARGET_MUSL)
+    set(MUSL 1)
+  endif ()
 endif (APPLE)
 if (WIN32)
   set(WINDOWS 1)

core/unix/include/siginfo.h

@@ -17,6 +17,7 @@
  * undef them here.
  */
 #include <signal.h>
+#include <limits.h>
 
 #ifdef MACOS
 /* For now we just use the system header. */
@@ -33,6 +34,11 @@ typedef clock_t __clock_t;
 #        ifndef __WORDSIZE
 #            define __WORDSIZE 32
 #        endif
+#    elif !defined(__GLIBC__)
+#        define __WORDSIZE LONG_BIT
+typedef uid_t __uid_t;
+typedef pid_t __pid_t;
+typedef clock_t __clock_t;
 #    else
 #        include <bits/wordsize.h>
 #    endif

core/unix/os.c

@@ -6408,6 +6408,8 @@ cleanup_after_vfork_execve(dcontext_t *dcontext)
                      num_threads * sizeof(thread_record_t *) HEAPACCT(ACCT_THREAD_MGT));
 }
 
+/* XXX: Discover libc type at runtime and use appropriate stdfile_t variant
+ * instead of depending on build-time preprocessor defines */
 static void
 set_stdfile_fileno(stdfile_t **stdfile, file_t old_fd, file_t file_no)
 {
@@ -6418,7 +6420,6 @@ set_stdfile_fileno(stdfile_t **stdfile, file_t old_fd, file_t file_no)
     (*stdfile)->STDFILE_FILENO = file_no;
 #    endif
 #else
-#    warning stdfile_t is opaque; DynamoRIO will not set fds of libc FILEs.
     /* i#1973: musl libc support (and potentially other non-glibcs) */
     /* only called by handle_close_pre(), so warning is specific to that. */
     SYSLOG_INTERNAL_WARNING_ONCE(

ext/drsyms/CMakeLists.txt

@@ -232,6 +232,10 @@ elseif (UNIX)
     # libdw uses pthread_rwlock_* routines.
     link_with_pthread(dw_pic)
 
+    if (MUSL)
+      target_sources(elf_pic PRIVATE "${elfutils_dir}/lib/error.c")
+    endif ()
+
     include_directories("${elfutils_dir}/libelf")
     include_directories("${elfutils_dir}/libdw")
     set(srcs ${srcs} drsyms_dw.c drsyms_elf.c)

ext/drsyms/elfutils/config.h

@@ -33,7 +33,9 @@
 
 /* Define if the GNU dcgettext() function is already present or preinstalled.
  */
-#define HAVE_DCGETTEXT 1
+#if !defined(__linux__) || defined(__GLIBC__)
+#    define HAVE_DCGETTEXT 1
+#endif
 
 /* Define to 1 if you have the declaration of `mempcpy', and to 0 if you
    don't. */
@@ -49,7 +51,9 @@
 
 /* Define to 1 if you have the declaration of `rawmemchr', and to 0 if you
    don't. */
-#define HAVE_DECL_RAWMEMCHR 1
+#if !defined(__linux__) || defined(__GLIBC__)
+#    define HAVE_DECL_RAWMEMCHR 1
+#endif
 
 /* Define to 1 if you have the declaration of `reallocarray', and to 0 if you
    don't. */
@@ -60,7 +64,9 @@
 #define HAVE_DECL_STRERROR_R 1
 
 /* Define to 1 if you have the <error.h> header file. */
-#define HAVE_ERROR_H 1
+#if !defined(__linux__) || defined(__GLIBC__)
+#    define HAVE_ERROR_H 1
+#endif
 
 /* Define to 1 if you have the <err.h> header file. */
 #define HAVE_ERR_H 1

make/configure.cmake.h

@@ -65,6 +65,7 @@
 /* Used a lot due to the different TLS.  We thus provide a convenience define. */
 # define MACOS64
 #endif
+#cmakedefine MUSL
 
 /* host, when different */
 #cmakedefine DR_HOST_X86

suite/tests/CMakeLists.txt

@@ -425,6 +425,11 @@ function (set_cflags source)
   else ()
     set(cflags "${ORIG_CMAKE_C_FLAGS}")
   endif ()
+  # Alpine Linux enables "-Wtrampolines" by default, breaking
+  # security-linux/trampoline.c.
+  if (MUSL)
+    set(cflags "${cflags} -Wno-trampolines")
+  endif ()
   if ("${source}" MATCHES ".cpp$")
     # Our C files need -std=gnu99, but that's an invalid flag for C++.
     # configure_DynamoRIO_global removes unfavorable options for clients,
@@ -2737,7 +2742,9 @@ else (UNIX)
 
   tobuild_ci(client.winxfer client-interface/winxfer.c "" "" "")
 endif (UNIX)
-if (NOT APPLE OR NOT AARCH64) # TODO i#5383: Port to Mac M1.
+# TODO i#5383: Port to Mac M1.
+# TODO i#1973: Port to musl libc.
+if (NOT APPLE OR NOT AARCH64 AND NOT MUSL)
   tobuild_ci(client.file_io client-interface/file_io.c
     "${CMAKE_CURRENT_SOURCE_DIR}/client-interface/file_io_data.txt" "" "")
 endif ()

suite/tests/linux/signal-base.h

@@ -77,6 +77,11 @@ static sigjmp_buf env;
 #    define ITERS 500000
 #endif
 
+/* i#1973: __SIGRTMAX isn't available on musl libc. */
+#ifndef __SIGRTMAX
+#    define __SIGRTMAX SIGRTMAX
+#endif
+
 #ifdef AARCHXX
 /* i#4719: Work around QEMU bugs where QEMU can't handle signals 63 or 64. */
 #    undef SIGRTMAX
@@ -151,25 +156,6 @@ static void
         break;
     }
 
-#ifdef LINUX
-    case __SIGRTMAX: {
-        sigcontext_t *sc = SIGCXT_FROM_UCXT(ucxt);
-        void *pc = (void *)sc->SC_XIP;
-        /* SIGRTMAX has been 64 on Linux since kernel 2.1, from looking at glibc
-         * sources. */
-#    ifndef AARCHXX /* i#4719: Work around QEMU bugs handling signals 63,64. */
-        assert(__SIGRTMAX == 64);
-#    endif
-        assert(__SIGRTMAX == SIGRTMAX);
-#    if VERBOSE
-        print("Got SIGRTMAX @ 0x%08x\n", pc);
-#    else
-        print("Got SIGRTMAX\n");
-#    endif
-        break;
-    }
-#endif
-
 #if USE_TIMER
     case SIGVTALRM: {
         sigcontext_t *sc = SIGCXT_FROM_UCXT(ucxt);
@@ -182,7 +168,28 @@ static void
     }
 #endif
 
-    default: assert(0);
+    default:
+        /* i#1973: SIGRTMAX is a macro over function call, rather than a constant on
+         * musl libc. We use an if branch in default block to handle this. */
+#ifdef LINUX
+        if (sig == __SIGRTMAX) {
+            sigcontext_t *sc = SIGCXT_FROM_UCXT(ucxt);
+            void *pc = (void *)sc->SC_XIP;
+            /* SIGRTMAX has been 64 on Linux since kernel 2.1, from looking at glibc
+             * sources. */
+#    ifndef AARCHXX /* i#4719: Work around QEMU bugs handling signals 63,64. */
+            assert(__SIGRTMAX == 64);
+#    endif
+            assert(__SIGRTMAX == SIGRTMAX);
+#    if VERBOSE
+            print("Got SIGRTMAX @ 0x%08x\n", pc);
+#    else
+            print("Got SIGRTMAX\n");
+#    endif
+            break;
+        }
+#endif
+        assert(0);
     }
 }
 

suite/tests/tools.c

@@ -381,6 +381,9 @@ nolibc_print(const char *str)
         3,
 #        if defined(MACOS) || defined(ANDROID)
         stderr->_file,
+    /* TODO i#1973: handle opaque FILE * on musl libc */
+#        elif defined(MUSL)
+        STDERR_FILENO,
 #        else
         stderr->_fileno,
 #        endif

suite/tests/tools.h

@@ -53,7 +53,62 @@
 #    include <sys/mman.h>
 #    include <stdlib.h> /* abort */
 #    include <errno.h>
+#    ifdef MUSL
+#        pragma push_macro("REG_R8")
+#        pragma push_macro("REG_R9")
+#        pragma push_macro("REG_R10")
+#        pragma push_macro("REG_R11")
+#        pragma push_macro("REG_R12")
+#        pragma push_macro("REG_R13")
+#        pragma push_macro("REG_R14")
+#        pragma push_macro("REG_R15")
+#        pragma push_macro("REG_RDI")
+#        pragma push_macro("REG_RSI")
+#        pragma push_macro("REG_RBP")
+#        pragma push_macro("REG_RBX")
+#        pragma push_macro("REG_RDX")
+#        pragma push_macro("REG_RAX")
+#        pragma push_macro("REG_RCX")
+#        pragma push_macro("REG_RSP")
+#        pragma push_macro("REG_CR2")
+#        undef REG_R8
+#        undef REG_R9
+#        undef REG_R10
+#        undef REG_R11
+#        undef REG_R12
+#        undef REG_R13
+#        undef REG_R14
+#        undef REG_R15
+#        undef REG_RDI
+#        undef REG_RSI
+#        undef REG_RBP
+#        undef REG_RBX
+#        undef REG_RDX
+#        undef REG_RAX
+#        undef REG_RCX
+#        undef REG_RSP
+#        undef REG_CR2
+#    endif
 #    include <signal.h>
+#    ifdef MUSL
+#        pragma pop_macro("REG_R8")
+#        pragma pop_macro("REG_R9")
+#        pragma pop_macro("REG_R10")
+#        pragma pop_macro("REG_R11")
+#        pragma pop_macro("REG_R12")
+#        pragma pop_macro("REG_R13")
+#        pragma pop_macro("REG_R14")
+#        pragma pop_macro("REG_R15")
+#        pragma pop_macro("REG_RDI")
+#        pragma pop_macro("REG_RSI")
+#        pragma pop_macro("REG_RBP")
+#        pragma pop_macro("REG_RBX")
+#        pragma pop_macro("REG_RDX")
+#        pragma pop_macro("REG_RAX")
+#        pragma pop_macro("REG_RCX")
+#        pragma pop_macro("REG_RSP")
+#        pragma pop_macro("REG_CR2")
+#    endif
 #    ifdef MACOS
 #        define _XOPEN_SOURCE \
             700 /* required to get POSIX, etc. defines out of ucontext.h */