From 670f82d437c21ec9c8f59a365336163e0381149d Mon Sep 17 00:00:00 2001 From: Tristan Gingold Date: Thu, 5 Mar 2015 14:36:32 +0100 Subject: [PATCH] Fix amd64 windows unwinding issues within MS dlls. Unwind info in system dlls uses almost all possible codes, contrary to unwind info generated by gcc. A few issues have been discovered: incorrect handling of SAVE_NONVOL opcodes and incorrect in prologue range checks. Furthermore I added comments not to forget what has been investigated. gdb/ChangeLog: * amd64-windows-tdep.c (amd64_windows_find_unwind_info): Move redirection code to ... (amd64_windows_frame_decode_insns): ... Here. Fix in prologue checks. Fix SAVE_NONVOL operations. Add debug code and comments. --- gdb/ChangeLog | 7 +++ gdb/amd64-windows-tdep.c | 115 ++++++++++++++++++++++++++++++++--------------- 2 files changed, 86 insertions(+), 36 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 222922f..41080ae 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,10 @@ +2015-03-18 Tristan Gingold + + * amd64-windows-tdep.c (amd64_windows_find_unwind_info): Move + redirection code to ... + (amd64_windows_frame_decode_insns): ... Here. Fix in prologue + checks. Fix SAVE_NONVOL operations. Add debug code and comments. + 2015-03-18 Gary Benson (remote_protocol_features): Remove the "vFile:fstat" feature. diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c index de5d8c7..a092298 100644 --- a/gdb/amd64-windows-tdep.c +++ b/gdb/amd64-windows-tdep.c @@ -621,9 +621,47 @@ amd64_windows_frame_decode_insns (struct frame_info *this_frame, CORE_ADDR cur_sp = cache->sp; struct gdbarch *gdbarch = get_frame_arch (this_frame); enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); - int j; + int first = 1; + + /* There are at least 3 possibilities to share an unwind info entry: + 1. Two different runtime_function entries (in .pdata) can point to the + same unwind info entry. There is no such indication while unwinding, + so we don't really care about that case. We suppose this scheme is + used to save memory when the unwind entries are exactly the same. + 2. Chained unwind_info entries, with no unwind codes (no prologue). + There is a major difference with the previous case: the pc range for + the function is different (in case 1, the pc range comes from the + runtime_function entry; in case 2, the pc range for the chained entry + comes from the first unwind entry). Case 1 cannot be used instead as + the pc is not in the prologue. This case is officially documented. + (There might be unwind code in the first unwind entry to handle + additional unwinding). GCC (at least until gcc 5.0) doesn't chain + entries. + 3. Undocumented unwind info redirection. Hard to know the exact purpose, + so it is considered as a memory optimization of case 2. + */ - for (j = 0; ; j++) + if (unwind_info & 1) + { + /* Unofficially documented unwind info redirection, when UNWIND_INFO + address is odd (http://www.codemachine.com/article_x64deepdive.html). + */ + struct external_pex64_runtime_function d; + CORE_ADDR sa, ea; + + if (target_read_memory (cache->image_base + (unwind_info & ~1), + (gdb_byte *) &d, sizeof (d)) != 0) + return; + + cache->start_rva + = extract_unsigned_integer (d.rva_BeginAddress, 4, byte_order); + cache->end_rva + = extract_unsigned_integer (d.rva_EndAddress, 4, byte_order); + unwind_info + = extract_unsigned_integer (d.rva_UnwindData, 4, byte_order); + } + + while (1) { struct external_pex64_unwind_info ex_ui; /* There are at most 256 16-bit unwind insns. */ @@ -633,6 +671,7 @@ amd64_windows_frame_decode_insns (struct frame_info *this_frame, unsigned char codes_count; unsigned char frame_reg; unsigned char frame_off; + CORE_ADDR start; /* Read and decode header. */ if (target_read_memory (cache->image_base + unwind_info, @@ -653,12 +692,13 @@ amd64_windows_frame_decode_insns (struct frame_info *this_frame, && PEX64_UWI_VERSION (ex_ui.Version_Flags) != 2) return; - if (j == 0 - && (cache->pc >= - cache->image_base + cache->start_rva + ex_ui.SizeOfPrologue)) + start = cache->image_base + cache->start_rva; + if (first + && !(cache->pc >= start && cache->pc < start + ex_ui.SizeOfPrologue)) { - /* Not in the prologue. We want to detect if the PC points to an - epilogue. If so, the epilogue detection+decoding function is + /* We want to detect if the PC points to an epilogue. This needs + to be checked only once, and an epilogue can be anywhere but in + the prologue. If so, the epilogue detection+decoding function is sufficient. Otherwise, the unwinder will consider that the PC is in the body of the function and will need to decode unwind info. */ @@ -711,19 +751,24 @@ amd64_windows_frame_decode_insns (struct frame_info *this_frame, { int reg; - if (frame_debug) - fprintf_unfiltered - (gdb_stdlog, " op #%u: off=0x%02x, insn=0x%02x\n", - (unsigned) (p - insns), p[0], p[1]); - - /* Virtually execute the operation. */ - if (cache->pc >= cache->image_base + cache->start_rva + p[0]) + /* Virtually execute the operation if the pc is after the + corresponding instruction (that does matter in case of break + within the prologue). Note that for chained info (!first), the + prologue has been fully executed. */ + if (cache->pc >= start + p[0] || cache->pc < start) { + if (frame_debug) + fprintf_unfiltered + (gdb_stdlog, " op #%u: off=0x%02x, insn=0x%02x\n", + (unsigned) (p - insns), p[0], p[1]); + /* If there is no frame registers defined, the current value of rsp is used instead. */ if (frame_reg == 0) save_addr = cur_sp; + reg = -1; + switch (PEX64_UNWCODE_CODE (p[1])) { case UWOP_PUSH_NONVOL: @@ -751,12 +796,12 @@ amd64_windows_frame_decode_insns (struct frame_info *this_frame, case UWOP_SAVE_NONVOL: reg = amd64_windows_w2gdb_regnum[PEX64_UNWCODE_INFO (p[1])]; cache->prev_reg_addr[reg] = save_addr - - 8 * extract_unsigned_integer (p + 2, 2, byte_order); + + 8 * extract_unsigned_integer (p + 2, 2, byte_order); break; case UWOP_SAVE_NONVOL_FAR: reg = amd64_windows_w2gdb_regnum[PEX64_UNWCODE_INFO (p[1])]; cache->prev_reg_addr[reg] = save_addr - - 8 * extract_unsigned_integer (p + 2, 4, byte_order); + + 8 * extract_unsigned_integer (p + 2, 4, byte_order); break; case UWOP_SAVE_XMM128: cache->prev_xmm_addr[PEX64_UNWCODE_INFO (p[1])] = @@ -787,6 +832,13 @@ amd64_windows_frame_decode_insns (struct frame_info *this_frame, default: return; } + + /* Display address where the register was saved. */ + if (frame_debug && reg >= 0) + fprintf_unfiltered + (gdb_stdlog, " [reg %s at %s]\n", + gdbarch_register_name (gdbarch, reg), + paddress (gdbarch, cache->prev_reg_addr[reg])); } /* Adjust with the length of the opcode. */ @@ -818,19 +870,29 @@ amd64_windows_frame_decode_insns (struct frame_info *this_frame, } } if (PEX64_UWI_FLAGS (ex_ui.Version_Flags) != UNW_FLAG_CHAININFO) - break; + { + /* End of unwind info. */ + break; + } else { /* Read the chained unwind info. */ struct external_pex64_runtime_function d; CORE_ADDR chain_vma; + /* Not anymore the first entry. */ + first = 0; + + /* Stay aligned on word boundary. */ chain_vma = cache->image_base + unwind_info + sizeof (ex_ui) + ((codes_count + 1) & ~1) * 2; if (target_read_memory (chain_vma, (gdb_byte *) &d, sizeof (d)) != 0) return; + /* Decode begin/end. This may be different from .pdata index, as + an unwind info may be shared by several functions (in particular + if many functions have the same prolog and handler. */ cache->start_rva = extract_unsigned_integer (d.rva_BeginAddress, 4, byte_order); cache->end_rva = @@ -940,25 +1002,6 @@ amd64_windows_find_unwind_info (struct gdbarch *gdbarch, CORE_ADDR pc, "amd64_windows_find_unwind_data: image_base=%s, unwind_data=%s\n", paddress (gdbarch, base), paddress (gdbarch, *unwind_info)); - if (*unwind_info & 1) - { - /* Unofficially documented unwind info redirection, when UNWIND_INFO - address is odd (http://www.codemachine.com/article_x64deepdive.html). - */ - struct external_pex64_runtime_function d; - CORE_ADDR sa, ea; - - if (target_read_memory (base + (*unwind_info & ~1), - (gdb_byte *) &d, sizeof (d)) != 0) - return -1; - - *start_rva = - extract_unsigned_integer (d.rva_BeginAddress, 4, byte_order); - *end_rva = extract_unsigned_integer (d.rva_EndAddress, 4, byte_order); - *unwind_info = - extract_unsigned_integer (d.rva_UnwindData, 4, byte_order); - - } return 0; } -- 2.7.4