Effectively implementing the debugger interface as described in https://sourceware.org/git/?p=glibc.git;a=blob;f=elf/rtld-debugger-interface...
This is an actual attempt at having this upstream, split from https://gitlab.winehq.org/wine/wine/-/merge_requests/1074 which people have been finding useful for debugging Wine directly in GDB. This supports everything you would expect, from automatic symbol loading as well as cross-syscall backtraces with the new Python unwinder.
-- v7: ntdll: Maintain a PE module link map and expose it to GDB. loader: Expose the standard debugging symbols for GDB.
From: Rémi Bernon rbernon@codeweavers.com
--- loader/main.c | 3 ++- loader/preloader.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 51 insertions(+), 1 deletion(-)
diff --git a/loader/main.c b/loader/main.c index 3467d29cb5c..0bd675bcc75 100644 --- a/loader/main.c +++ b/loader/main.c @@ -73,7 +73,8 @@ static void init_reserved_areas(void)
#else
-/* the preloader will set this variable */ +/* the preloader will set these variables */ +__attribute((visibility("default"))) struct r_debug *wine_r_debug = NULL; const __attribute((visibility("default"))) struct wine_preload_info *wine_main_preload_info = NULL;
static void init_reserved_areas(void) diff --git a/loader/preloader.c b/loader/preloader.c index d0551bae63a..67452f8b24d 100644 --- a/loader/preloader.c +++ b/loader/preloader.c @@ -79,12 +79,16 @@ #ifdef HAVE_ELF_H # include <elf.h> #endif + +/* define _r_debug so we can re-define it as r_debug_extended */ +#define _r_debug no_r_debug; #ifdef HAVE_LINK_H # include <link.h> #endif #ifdef HAVE_SYS_LINK_H # include <sys/link.h> #endif +#undef _r_debug
#include "wine/asm.h" #include "main.h" @@ -1387,6 +1391,39 @@ static void set_process_name( int argc, char *argv[] ) for (i = 1; i < argc; i++) argv[i] -= off; }
+struct wld_r_debug_extended +{ + struct r_debug base; + struct wld_r_debug_extended *r_next; +}; + +/* GDB integration, _r_debug_state is *required* for GDB to hook the preloader */ +__attribute((visibility("default"))) void _r_debug_state(void) {} +__attribute((visibility("default"))) struct wld_r_debug_extended _r_debug = {{0}}; + +/* sets the preloader r_debug address into DT_DEBUG */ +static void init_r_debug( struct wld_auxv *av ) +{ + ElfW(Phdr) *phdr, *ph; + ElfW(Dyn) *dyn = NULL; + char *l_addr; + int phnum; + + _r_debug.base.r_version = 2; + _r_debug.base.r_brk = (ElfW(Addr))_r_debug_state; + + if (!(phnum = get_auxiliary( av, AT_PHNUM, 0 ))) return; + if (!(phdr = (void *)get_auxiliary( av, AT_PHDR, 0 ))) return; + l_addr = (char *)phdr - sizeof(ElfW(Ehdr)); + _r_debug.base.r_ldbase = (ElfW(Addr))l_addr; + + for (ph = phdr; ph < &phdr[phnum]; ++ph) if (ph->p_type == PT_DYNAMIC) break; + if (ph >= &phdr[phnum]) return; + + dyn = (void *)(ph->p_vaddr + l_addr); + while (dyn->d_tag != DT_DEBUG && dyn->d_tag != DT_NULL) dyn++; + if (dyn->d_tag == DT_DEBUG) dyn->d_un.d_ptr = (uintptr_t)&_r_debug; +}
/* * wld_start @@ -1403,6 +1440,7 @@ void* wld_start( void **stack ) struct wld_auxv new_av[8], delete_av[3], *av; struct wld_link_map main_binary_map, ld_so_map; struct wine_preload_info **wine_main_preload_info; + struct r_debug *ld_so_r_debug, **wine_r_debug;
pargc = *stack; argv = (char **)pargc + 1; @@ -1432,6 +1470,8 @@ void* wld_start( void **stack ) dump_auxiliary( av ); #endif
+ init_r_debug( av ); + /* reserve memory that Wine needs */ if (reserve) preload_reserve( reserve ); for (i = 0; preload_info[i].size; i++) @@ -1470,6 +1510,15 @@ void* wld_start( void **stack ) interp = (char *)main_binary_map.l_addr + main_binary_map.l_interp; map_so_lib( interp, &ld_so_map );
+ /* expose ld.so _r_debug as a separate namespace in r_next */ + ld_so_r_debug = find_symbol( &ld_so_map, "_r_debug", STT_OBJECT ); + if (ld_so_r_debug) _r_debug.r_next = (struct wld_r_debug_extended *)ld_so_r_debug; + else wld_printf( "_r_debug not found in ld.so\n" ); + + wine_r_debug = find_symbol( &main_binary_map, "wine_r_debug", STT_OBJECT ); + if (wine_r_debug) *wine_r_debug = &_r_debug.base; + else wld_printf( "wine_r_debug not found\n" ); + /* store pointer to the preload info into the appropriate main binary variable */ wine_main_preload_info = find_symbol( &main_binary_map, "wine_main_preload_info", STT_OBJECT ); if (wine_main_preload_info) *wine_main_preload_info = preload_info;
From: Rémi Bernon rbernon@codeweavers.com
--- dlls/ntdll/unix/virtual.c | 130 +++++++++++++++++++++++++++++++++++++- 1 file changed, 129 insertions(+), 1 deletion(-)
diff --git a/dlls/ntdll/unix/virtual.c b/dlls/ntdll/unix/virtual.c index 40cea6efe53..7a58a0b3bef 100644 --- a/dlls/ntdll/unix/virtual.c +++ b/dlls/ntdll/unix/virtual.c @@ -54,6 +54,12 @@ #ifdef HAVE_SYS_USER_H # include <sys/user.h> #endif +#ifdef HAVE_LINK_H +# include <link.h> +#endif +#ifdef HAVE_SYS_LINK_H +# include <sys/link.h> +#endif #ifdef HAVE_LIBPROCSTAT_H # include <libprocstat.h> #endif @@ -85,6 +91,120 @@ WINE_DEFAULT_DEBUG_CHANNEL(virtual); WINE_DECLARE_DEBUG_CHANNEL(module); WINE_DECLARE_DEBUG_CHANNEL(virtual_ranges);
+/* Gdb integration, in loader/main.c */ +static struct r_debug *wine_r_debug; + +#if defined(HAVE_LINK_H) || defined(HAVE_SYS_LINK_H) + +struct link_map_entry +{ + struct link_map map; + const void *module; +}; +static struct link_map link_map = {.l_name = (char *)""}; + +static void r_debug_set_state( int state ) +{ + wine_r_debug->r_map = &link_map; + wine_r_debug->r_state = state; + ((void (*)(void))wine_r_debug->r_brk)(); +} + +static char *get_path_from_fd( int fd, int sz ) +{ +#ifdef linux + char *ret = malloc( 32 + sz ); + + if (ret) sprintf( ret, "/proc/self/fd/%u", fd ); + return ret; +#elif defined(F_GETPATH) + char *ret = malloc( PATH_MAX + sz ); + + if (!ret) return NULL; + if (!fcntl( fd, F_GETPATH, ret )) return ret; + free( ret ); + return NULL; +#else + return NULL; +#endif +} + +static char *r_debug_path_from_fd( int fd ) +{ + char *real, *path; + if (!(path = get_path_from_fd( fd, 0 ))) return NULL; + if (!(real = realpath( path, NULL ))) return path; + free( path ); + return real; +} + +static void r_debug_add_module( void *module, int fd, INT_PTR offset ) +{ + struct link_map *ptr = link_map.l_next, *next; + struct link_map_entry *entry; + + if (!wine_r_debug) return; + + while (ptr) + { + entry = LIST_ENTRY(ptr, struct link_map_entry, map); + if (entry->module == module) break; + ptr = ptr->l_next; + } + + r_debug_set_state( RT_ADD ); + + if (ptr) entry->map.l_addr = offset; + else if ((entry = calloc( 1, sizeof(*entry) ))) + { + entry->module = module; + entry->map.l_addr = offset; + entry->map.l_name = r_debug_path_from_fd( fd ); + + entry->map.l_next = link_map.l_next; + if ((next = entry->map.l_next)) next->l_prev = &entry->map; + entry->map.l_prev = &link_map; + link_map.l_next = &entry->map; + } + + r_debug_set_state( RT_CONSISTENT ); +} + +static void r_debug_remove_module( void *module ) +{ + struct link_map *ptr = link_map.l_next, *next; + struct link_map_entry *entry; + + if (!wine_r_debug) return; + + while (ptr) + { + entry = LIST_ENTRY(ptr, struct link_map_entry, map); + if (entry->module == module) break; + ptr = ptr->l_next; + } + if (!ptr) return; + + r_debug_set_state( RT_DELETE ); + + entry->map.l_prev->l_next = entry->map.l_next; + if ((next = entry->map.l_next)) next->l_prev = entry->map.l_prev; + + r_debug_set_state( RT_CONSISTENT ); + + free( entry->map.l_name ); + free( entry ); +} + +#else /* defined(HAVE_LINK_H) || defined(HAVE_SYS_LINK_H) */ + +#define RT_CONSISTENT 0 +static void r_debug_set_state( int state ) {} +static void r_debug_add_module( void *module, int fd, INT_PTR offset ) {} +static void r_debug_remove_module( void *module ) {} + +#endif /* defined(HAVE_LINK_H) || defined(HAVE_SYS_LINK_H) */ + struct preload_info { void *addr; @@ -2962,6 +3082,7 @@ static NTSTATUS map_image_into_view( struct file_view *view, const WCHAR *filena #ifdef VALGRIND_LOAD_PDB_DEBUGINFO VALGRIND_LOAD_PDB_DEBUGINFO(fd, ptr, total_size, ptr - (char *)wine_server_get_ptr( image_info->base )); #endif + r_debug_add_module( ptr, fd, ptr - (char *)wine_server_get_ptr( image_info->base ) ); return STATUS_SUCCESS; }
@@ -3324,11 +3445,14 @@ static void *alloc_virtual_heap( SIZE_T size ) void virtual_init(void) { const struct preload_info **preload_info = dlsym( RTLD_DEFAULT, "wine_main_preload_info" ); + struct r_debug **r_debug = dlsym( RTLD_DEFAULT, "wine_r_debug" ); const char *preload; size_t size; int i; pthread_mutexattr_t attr;
+ if (r_debug && (wine_r_debug = *r_debug)) r_debug_set_state( RT_CONSISTENT ); + pthread_mutexattr_init( &attr ); pthread_mutexattr_settype( &attr, PTHREAD_MUTEX_RECURSIVE ); pthread_mutex_init( &virtual_mutex, &attr ); @@ -5840,7 +5964,11 @@ static NTSTATUS unmap_view_of_section( HANDLE process, PVOID addr, ULONG flags ) SERVER_END_REQ; if (!status) { - if (view->protect & SEC_IMAGE) release_builtin_module( view->base ); + if (view->protect & SEC_IMAGE) + { + r_debug_remove_module( view->base ); + release_builtin_module( view->base ); + } if (flags & MEM_PRESERVE_PLACEHOLDER) free_pages_preserve_placeholder( view, view->base, view->size ); else delete_view( view ); }
Hello, thanks for maintaining this branch. I thought this might be help plain linux lldb too, but I don't know how to convince it to take PEs. Has someone already solved this? ``` $ lldb-19 (lldb) log enable lldb module dyld (lldb) process attach --pid 3848257 ... intern-state 0x7feba4083e90 Module::Module((x86_64) '.../obj/dlls/msimg32/x86_64-windows/msimg32.dll') intern-state Found local object file but the specs didn't match ```
I don't know either, I had a look but it seemed deeply rooted in lldb and its expected module format was driven by the process target, and it refuses to load anything else than ELF if the process is detected as a Linux native process.
On Wed Jun 25 12:53:03 2025 +0000, Rémi Bernon wrote:
I don't know either, I had a look but it seemed deeply rooted in lldb and its expected module format was driven by the process target, and it refuses to load anything else than ELF if the process is detected as a Linux native process.
Unfortunately I found no cheaper way, but following steps allowed me to get over the `Found local object file but the specs didn't match` message by rebuilding a local lldb with a small patch.
``` git clone https://github.com/llvm/llvm-project.git cd llvm-project # git as of 52b27c2b # apply the patch below mkdir build_optdebug && cd build_optdebug CC=/usr/bin/clang-19 CXX=/usr/bin/clang++-19 cmake -GNinja -DLLVM_ENABLE_PROJECTS="clang;lldb" -DCMAKE_BUILD_TYPE=RelWithDebInfo ../llvm ninja -j10 lldb lldb-server ``` ```diff diff --git a/lldb/source/Utility/ArchSpec.cpp b/lldb/source/Utility/ArchSpec.cpp index 70b9800f4dad..37016f1e4ce7 100644 --- a/lldb/source/Utility/ArchSpec.cpp +++ b/lldb/source/Utility/ArchSpec.cpp @@ -1014,6 +1014,7 @@ bool ArchSpec::IsMatch(const ArchSpec &rhs, MatchType match) const { // On Windows, the vendor field doesn't have any practical effect, but // it is often set to either "pc" or "w64". if ((lhs_triple_vendor != rhs_triple_vendor) && + (lhs_triple_vendor != llvm::Triple::PC && rhs_triple_vendor != llvm::Triple::UnknownVendor) && (match == ExactMatch || !both_windows)) { const bool rhs_vendor_specified = rhs.TripleVendorWasSpecified(); const bool lhs_vendor_specified = TripleVendorWasSpecified(); @@ -1034,6 +1035,12 @@ bool ArchSpec::IsMatch(const ArchSpec &rhs, MatchType match) const { rhs_triple.getEnvironment();
if (match == CompatibleMatch) { + // wine-preloader, x86_64-unknown-linux-gnu, loads Windows dlls x86_64-pc-windows-msvc + if ((lhs_triple_os == llvm::Triple::Win32 && + lhs_triple_env == llvm::Triple::MSVC && + rhs_triple_os == llvm::Triple::Linux && + rhs_triple_env == llvm::Triple::GNU)) + return true; // x86_64-apple-ios-macabi, x86_64-apple-macosx are compatible, no match. if ((lhs_triple_os == llvm::Triple::IOS && lhs_triple_env == llvm::Triple::MacABI && ``` ``` $ /full/path/to/llvm-project/build_optdebug/bin/lldb (lldb) log enable lldb module dyld (lldb) process attach --pid 3848257 (lldb) process handle --pass true --stop false --notify false SIGUSR1 ... (lldb) bt * thread #1, name = 'notepad.exe', stop reason = breakpoint 1.1 * frame #0: 0x00006ffffd384c66 user32.dll`WINPROC_wrapper(proc=(comctl32.dll`COMCTL32_SubclassProc at commctrl.c:1228), hwnd=0x0000000000010086, msg=256, wParam=144, lParam=21299201) at winproc.c:86:12 frame #1: 0x00006ffffd38389d user32.dll`call_window_proc(hwnd=<unavailable>, msg=256, wp=<unavailable>, lp=21299201, result=0x00007ffffe1ffb68, arg=0x00006ffffdbcd680) at winproc.c:111:15 frame #2: 0x00006ffffd3839ff user32.dll`dispatch_win_proc_params(params=0x00007ffffe1ffbc8) at winproc.c:0 frame #3: 0x00006ffffd36ff4e user32.dll`dispatch_message(msg=0x00007ffffe1ffcc0, ansi=<unavailable>) at message.c:805:14 frame #4: 0x00006ffffd37000a user32.dll`DispatchMessageW(msg=0x00007ffffe1ffcc0) at message.c:891:16 frame #5: 0x0000000140009817 notepad.exe`WinMain(hInstance=0x0000000140000000, prev=<unavailable>, cmdline=<unavailable>, show=<unavailable>) at main.c:852:13 ```
It allows also me to add symbol information from PDB files to a mshtml_test.exe process: ``` (lldb) target symbols add .../drive_c/windows/system32/gecko/2.47.4/wine_gecko/xul.dll' ```
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Bernhard Übelacker (＠bernhardu) -
Rémi Bernon
-
Rémi Bernon (＠rbernon)