/* seh pdata/xdata coff object file format Copyright (C) 2009-2017 Free Software Foundation, Inc. This file is part of GAS. GAS is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GAS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GAS; see the file COPYING. If not, write to the Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ #include "obj-coff-seh.h" /* Private segment collection list. */ struct seh_seg_list { segT seg; int subseg; char *seg_name; }; /* Local data. */ static seh_context *seh_ctx_cur = NULL; static struct hash_control *seh_hash; static struct seh_seg_list *x_segcur = NULL; static struct seh_seg_list *p_segcur = NULL; static void write_function_xdata (seh_context *); static void write_function_pdata (seh_context *); /* Build based on segment the derived .pdata/.xdata segment name containing origin segment's postfix name part. */ static char * get_pxdata_name (segT seg, const char *base_name) { const char *name,*dollar, *dot; char *sname; name = bfd_get_section_name (stdoutput, seg); dollar = strchr (name, '$'); dot = strchr (name + 1, '.'); if (!dollar && !dot) name = ""; else if (!dollar) name = dot; else if (!dot) name = dollar; else if (dot < dollar) name = dot; else name = dollar; sname = concat (base_name, name, NULL); return sname; } /* Allocate a seh_seg_list structure. */ static struct seh_seg_list * alloc_pxdata_item (segT seg, int subseg, char *name) { struct seh_seg_list *r; r = (struct seh_seg_list *) xmalloc (sizeof (struct seh_seg_list) + strlen (name)); r->seg = seg; r->subseg = subseg; r->seg_name = name; return r; } /* Generate pdata/xdata segment with same linkonce properties of based segment. */ static segT make_pxdata_seg (segT cseg, char *name) { segT save_seg = now_seg; int save_subseg = now_subseg; segT r; flagword flags; r = subseg_new (name, 0); /* Check if code segment is marked as linked once. */ flags = bfd_get_section_flags (stdoutput, cseg) & (SEC_LINK_ONCE | SEC_LINK_DUPLICATES_DISCARD | SEC_LINK_DUPLICATES_ONE_ONLY | SEC_LINK_DUPLICATES_SAME_SIZE | SEC_LINK_DUPLICATES_SAME_CONTENTS); /* Add standard section flags. */ flags |= SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_DATA; /* Apply possibly linked once flags to new generated segment, too. */ if (!bfd_set_section_flags (stdoutput, r, flags)) as_bad (_("bfd_set_section_flags: %s"), bfd_errmsg (bfd_get_error ())); /* Restore to previous segment. */ subseg_set (save_seg, save_subseg); return r; } static void seh_hash_insert (const char *name, struct seh_seg_list *item) { const char *error_string; if ((error_string = hash_jam (seh_hash, name, (char *) item))) as_fatal (_("Inserting \"%s\" into structure table failed: %s"), name, error_string); } static struct seh_seg_list * seh_hash_find (char *name) { return (struct seh_seg_list *) hash_find (seh_hash, name); } static struct seh_seg_list * seh_hash_find_or_make (segT cseg, const char *base_name) { struct seh_seg_list *item; char *name; /* Initialize seh_hash once. */ if (!seh_hash) seh_hash = hash_new (); name = get_pxdata_name (cseg, base_name); item = seh_hash_find (name); if (!item) { item = alloc_pxdata_item (make_pxdata_seg (cseg, name), 0, name); seh_hash_insert (item->seg_name, item); } else free (name); return item; } /* Check if current segment has same name. */ static int seh_validate_seg (const char *directive) { const char *cseg_name, *nseg_name; if (seh_ctx_cur->code_seg == now_seg) return 1; cseg_name = bfd_get_section_name (stdoutput, seh_ctx_cur->code_seg); nseg_name = bfd_get_section_name (stdoutput, now_seg); as_bad (_("%s used in segment '%s' instead of expected '%s'"), directive, nseg_name, cseg_name); ignore_rest_of_line (); return 0; } /* Switch back to the code section, whatever that may be. */ static void obj_coff_seh_code (int ignored ATTRIBUTE_UNUSED) { subseg_set (seh_ctx_cur->code_seg, 0); } static void switch_xdata (int subseg, segT code_seg) { x_segcur = seh_hash_find_or_make (code_seg, ".xdata"); subseg_set (x_segcur->seg, subseg); } static void switch_pdata (segT code_seg) { p_segcur = seh_hash_find_or_make (code_seg, ".pdata"); subseg_set (p_segcur->seg, p_segcur->subseg); } /* Parsing routines. */ /* Return the style of SEH unwind info to generate. */ static seh_kind seh_get_target_kind (void) { if (!stdoutput) return seh_kind_unknown; switch (bfd_get_arch (stdoutput)) { case bfd_arch_arm: case bfd_arch_powerpc: case bfd_arch_sh: return seh_kind_arm; case bfd_arch_i386: switch (bfd_get_mach (stdoutput)) { case bfd_mach_x86_64: case bfd_mach_x86_64_intel_syntax: return seh_kind_x64; default: break; } /* FALL THROUGH. */ case bfd_arch_mips: return seh_kind_mips; case bfd_arch_ia64: /* Should return seh_kind_x64. But not implemented yet. */ return seh_kind_unknown; default: break; } return seh_kind_unknown; } /* Verify that we're in the context of a seh_proc. */ static int verify_context (const char *directive) { if (seh_ctx_cur == NULL) { as_bad (_("%s used outside of .seh_proc block"), directive); ignore_rest_of_line (); return 0; } return 1; } /* Similar, except we also verify the appropriate target. */ static int verify_context_and_target (const char *directive, seh_kind target) { if (seh_get_target_kind () != target) { as_warn (_("%s ignored for this target"), directive); ignore_rest_of_line (); return 0; } return verify_context (directive); } /* Skip whitespace and a comma. Error if the comma is not seen. */ static int skip_whitespace_and_comma (int required) { SKIP_WHITESPACE (); if (*input_line_pointer == ',') { input_line_pointer++; SKIP_WHITESPACE (); return 1; } else if (required) { as_bad (_("missing separator")); ignore_rest_of_line (); } else demand_empty_rest_of_line (); return 0; } /* Mark current context to use 32-bit instruction (arm). */ static void obj_coff_seh_32 (int what) { if (!verify_context_and_target ((what ? ".seh_32" : ".seh_no32"), seh_kind_arm)) return; seh_ctx_cur->use_instruction_32 = (what ? 1 : 0); demand_empty_rest_of_line (); } /* Set for current context the handler and optional data (arm). */ static void obj_coff_seh_eh (int what ATTRIBUTE_UNUSED) { if (!verify_context_and_target (".seh_eh", seh_kind_arm)) return; /* Write block to .text if exception handler is set. */ seh_ctx_cur->handler_written = 1; emit_expr (&seh_ctx_cur->handler, 4); emit_expr (&seh_ctx_cur->handler_data, 4); demand_empty_rest_of_line (); } /* Set for current context the default handler (x64). */ static void obj_coff_seh_handler (int what ATTRIBUTE_UNUSED) { char *symbol_name; char name_end; if (!verify_context (".seh_handler")) return; if (*input_line_pointer == 0 || *input_line_pointer == '\n') { as_bad (_(".seh_handler requires a handler")); demand_empty_rest_of_line (); return; } SKIP_WHITESPACE (); if (*input_line_pointer == '@') { name_end = get_symbol_name (&symbol_name); seh_ctx_cur->handler.X_op = O_constant; seh_ctx_cur->handler.X_add_number = 0; if (strcasecmp (symbol_name, "@0") == 0 || strcasecmp (symbol_name, "@null") == 0) ; else if (strcasecmp (symbol_name, "@1") == 0) seh_ctx_cur->handler.X_add_number = 1; else as_bad (_("unknown constant value '%s' for handler"), symbol_name); (void) restore_line_pointer (name_end); } else expression (&seh_ctx_cur->handler); seh_ctx_cur->handler_data.X_op = O_constant; seh_ctx_cur->handler_data.X_add_number = 0; seh_ctx_cur->handler_flags = 0; if (!skip_whitespace_and_comma (0)) return; if (seh_get_target_kind () == seh_kind_x64) { do { name_end = get_symbol_name (&symbol_name); if (strcasecmp (symbol_name, "@unwind") == 0) seh_ctx_cur->handler_flags |= UNW_FLAG_UHANDLER; else if (strcasecmp (symbol_name, "@except") == 0) seh_ctx_cur->handler_flags |= UNW_FLAG_EHANDLER; else as_bad (_(".seh_handler constant '%s' unknown"), symbol_name); (void) restore_line_pointer (name_end); } while (skip_whitespace_and_comma (0)); } else { expression (&seh_ctx_cur->handler_data); demand_empty_rest_of_line (); if (seh_ctx_cur->handler_written) as_warn (_(".seh_handler after .seh_eh is ignored")); } } /* Switch to subsection for handler data for exception region (x64). */ static void obj_coff_seh_handlerdata (int what ATTRIBUTE_UNUSED) { if (!verify_context_and_target (".seh_handlerdata", seh_kind_x64)) return; demand_empty_rest_of_line (); switch_xdata (seh_ctx_cur->subsection + 1, seh_ctx_cur->code_seg); } /* Mark end of current context. */ static void do_seh_endproc (void) { seh_ctx_cur->end_addr = symbol_temp_new_now (); write_function_xdata (seh_ctx_cur); write_function_pdata (seh_ctx_cur); seh_ctx_cur = NULL; } static void obj_coff_seh_endproc (int what ATTRIBUTE_UNUSED) { demand_empty_rest_of_line (); if (seh_ctx_cur == NULL) { as_bad (_(".seh_endproc used without .seh_proc")); return; } seh_validate_seg (".seh_endproc"); do_seh_endproc (); } /* Mark begin of new context. */ static void obj_coff_seh_proc (int what ATTRIBUTE_UNUSED) { char *symbol_name; char name_end; if (seh_ctx_cur != NULL) { as_bad (_("previous SEH entry not closed (missing .seh_endproc)")); do_seh_endproc (); } if (*input_line_pointer == 0 || *input_line_pointer == '\n') { as_bad (_(".seh_proc requires function label name")); demand_empty_rest_of_line (); return; } seh_ctx_cur = XCNEW (seh_context); seh_ctx_cur->code_seg = now_seg; if (seh_get_target_kind () == seh_kind_x64) { x_segcur = seh_hash_find_or_make (seh_ctx_cur->code_seg, ".xdata"); seh_ctx_cur->subsection = x_segcur->subseg; x_segcur->subseg += 2; } SKIP_WHITESPACE (); name_end = get_symbol_name (&symbol_name); seh_ctx_cur->func_name = xstrdup (symbol_name); (void) restore_line_pointer (name_end); demand_empty_rest_of_line (); seh_ctx_cur->start_addr = symbol_temp_new_now (); } /* Mark end of prologue for current context. */ static void obj_coff_seh_endprologue (int what ATTRIBUTE_UNUSED) { if (!verify_context (".seh_endprologue") || !seh_validate_seg (".seh_endprologue")) return; demand_empty_rest_of_line (); if (seh_ctx_cur->endprologue_addr != NULL) as_warn (_("duplicate .seh_endprologue in .seh_proc block")); else seh_ctx_cur->endprologue_addr = symbol_temp_new_now (); } /* End-of-file hook. */ void obj_coff_seh_do_final (void) { if (seh_ctx_cur != NULL) as_bad (_("open SEH entry at end of file (missing .seh_endproc)")); } /* Enter a prologue element into current context (x64). */ static void seh_x64_make_prologue_element (int code, int info, offsetT off) { seh_prologue_element *n; if (seh_ctx_cur == NULL) return; if (seh_ctx_cur->elems_count == seh_ctx_cur->elems_max) { seh_ctx_cur->elems_max += 8; seh_ctx_cur->elems = XRESIZEVEC (seh_prologue_element, seh_ctx_cur->elems, seh_ctx_cur->elems_max); } n = &seh_ctx_cur->elems[seh_ctx_cur->elems_count++]; n->code = code; n->info = info; n->off = off; n->pc_addr = symbol_temp_new_now (); } /* Helper to read a register name from input stream (x64). */ static int seh_x64_read_reg (const char *directive, int kind) { static const char * const int_regs[16] = { "rax", "rcx", "rdx", "rbx", "rsp", "rbp","rsi","rdi", "r8","r9","r10","r11","r12","r13","r14","r15" }; static const char * const xmm_regs[16] = { "xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7", "xmm8", "xmm9", "xmm10","xmm11","xmm12","xmm13","xmm14","xmm15" }; const char * const *regs = NULL; char name_end; char *symbol_name = NULL; int i; switch (kind) { case 0: case 1: regs = int_regs; break; case 2: regs = xmm_regs; break; default: abort (); } SKIP_WHITESPACE (); if (*input_line_pointer == '%') ++input_line_pointer; name_end = get_symbol_name (& symbol_name); for (i = 0; i < 16; i++) if (! strcasecmp (regs[i], symbol_name)) break; (void) restore_line_pointer (name_end); /* Error if register not found, or EAX used as a frame pointer. */ if (i == 16 || (kind == 0 && i == 0)) { as_bad (_("invalid register for %s"), directive); return -1; } return i; } /* Add a register push-unwind token to the current context. */ static void obj_coff_seh_pushreg (int what ATTRIBUTE_UNUSED) { int reg; if (!verify_context_and_target (".seh_pushreg", seh_kind_x64) || !seh_validate_seg (".seh_pushreg")) return; reg = seh_x64_read_reg (".seh_pushreg", 1); demand_empty_rest_of_line (); if (reg < 0) return; seh_x64_make_prologue_element (UWOP_PUSH_NONVOL, reg, 0); } /* Add a register frame-unwind token to the current context. */ static void obj_coff_seh_pushframe (int what ATTRIBUTE_UNUSED) { if (!verify_context_and_target (".seh_pushframe", seh_kind_x64) || !seh_validate_seg (".seh_pushframe")) return; demand_empty_rest_of_line (); seh_x64_make_prologue_element (UWOP_PUSH_MACHFRAME, 0, 0); } /* Add a register save-unwind token to current context. */ static void obj_coff_seh_save (int what) { const char *directive = (what == 1 ? ".seh_savereg" : ".seh_savexmm"); int code, reg, scale; offsetT off; if (!verify_context_and_target (directive, seh_kind_x64) || !seh_validate_seg (directive)) return; reg = seh_x64_read_reg (directive, what); if (!skip_whitespace_and_comma (1)) return; off = get_absolute_expression (); demand_empty_rest_of_line (); if (reg < 0) return; if (off < 0) { as_bad (_("%s offset is negative"), directive); return; } scale = (what == 1 ? 8 : 16); if ((off & (scale - 1)) == 0 && off <= (offsetT) (0xffff * scale)) { code = (what == 1 ? UWOP_SAVE_NONVOL : UWOP_SAVE_XMM128); off /= scale; } else if (off < (offsetT) 0xffffffff) code = (what == 1 ? UWOP_SAVE_NONVOL_FAR : UWOP_SAVE_XMM128_FAR); else { as_bad (_("%s offset out of range"), directive); return; } seh_x64_make_prologue_element (code, reg, off); } /* Add a stack-allocation token to current context. */ static void obj_coff_seh_stackalloc (int what ATTRIBUTE_UNUSED) { offsetT off; int code, info; if (!verify_context_and_target (".seh_stackalloc", seh_kind_x64) || !seh_validate_seg (".seh_stackalloc")) return; off = get_absolute_expression (); demand_empty_rest_of_line (); if (off == 0) return; if (off < 0) { as_bad (_(".seh_stackalloc offset is negative")); return; } if ((off & 7) == 0 && off <= 128) code = UWOP_ALLOC_SMALL, info = (off - 8) >> 3, off = 0; else if ((off & 7) == 0 && off <= (offsetT) (0xffff * 8)) code = UWOP_ALLOC_LARGE, info = 0, off >>= 3; else if (off <= (offsetT) 0xffffffff) code = UWOP_ALLOC_LARGE, info = 1; else { as_bad (_(".seh_stackalloc offset out of range")); return; } seh_x64_make_prologue_element (code, info, off); } /* Add a frame-pointer token to current context. */ static void obj_coff_seh_setframe (int what ATTRIBUTE_UNUSED) { offsetT off; int reg; if (!verify_context_and_target (".seh_setframe", seh_kind_x64) || !seh_validate_seg (".seh_setframe")) return; reg = seh_x64_read_reg (".seh_setframe", 0); if (!skip_whitespace_and_comma (1)) return; off = get_absolute_expression (); demand_empty_rest_of_line (); if (reg < 0) return; if (off < 0) as_bad (_(".seh_setframe offset is negative")); else if (off > 240) as_bad (_(".seh_setframe offset out of range")); else if (off & 15) as_bad (_(".seh_setframe offset not a multiple of 16")); else if (seh_ctx_cur->framereg != 0) as_bad (_("duplicate .seh_setframe in current .seh_proc")); else { seh_ctx_cur->framereg = reg; seh_ctx_cur->frameoff = off; seh_x64_make_prologue_element (UWOP_SET_FPREG, 0, 0); } } /* Data writing routines. */ /* Output raw integers in 1, 2, or 4 bytes. */ static inline void out_one (int byte) { FRAG_APPEND_1_CHAR (byte); } static inline void out_two (int data) { md_number_to_chars (frag_more (2), data, 2); } static inline void out_four (int data) { md_number_to_chars (frag_more (4), data, 4); } /* Write out prologue data for x64. */ static void seh_x64_write_prologue_data (const seh_context *c) { int i; /* We have to store in reverse order. */ for (i = c->elems_count - 1; i >= 0; --i) { const seh_prologue_element *e = c->elems + i; expressionS exp; /* First comes byte offset in code. */ exp.X_op = O_subtract; exp.X_add_symbol = e->pc_addr; exp.X_op_symbol = c->start_addr; exp.X_add_number = 0; emit_expr (&exp, 1); /* Second comes code+info packed into a byte. */ out_one ((e->info << 4) | e->code); switch (e->code) { case UWOP_PUSH_NONVOL: case UWOP_ALLOC_SMALL: case UWOP_SET_FPREG: case UWOP_PUSH_MACHFRAME: /* These have no extra data. */ break; case UWOP_ALLOC_LARGE: if (e->info) { case UWOP_SAVE_NONVOL_FAR: case UWOP_SAVE_XMM128_FAR: /* An unscaled 4 byte offset. */ out_four (e->off); break; } /* FALLTHRU */ case UWOP_SAVE_NONVOL: case UWOP_SAVE_XMM128: /* A scaled 2 byte offset. */ out_two (e->off); break; default: abort (); } } } static int seh_x64_size_prologue_data (const seh_context *c) { int i, ret = 0; for (i = c->elems_count - 1; i >= 0; --i) switch (c->elems[i].code) { case UWOP_PUSH_NONVOL: case UWOP_ALLOC_SMALL: case UWOP_SET_FPREG: case UWOP_PUSH_MACHFRAME: ret += 1; break; case UWOP_SAVE_NONVOL: case UWOP_SAVE_XMM128: ret += 2; break; case UWOP_SAVE_NONVOL_FAR: case UWOP_SAVE_XMM128_FAR: ret += 3; break; case UWOP_ALLOC_LARGE: ret += (c->elems[i].info ? 3 : 2); break; default: abort (); } return ret; } /* Write out the xdata information for one function (x64). */ static void seh_x64_write_function_xdata (seh_context *c) { int flags, count_unwind_codes; expressionS exp; /* Set 4-byte alignment. */ frag_align (2, 0, 0); c->xdata_addr = symbol_temp_new_now (); flags = c->handler_flags; count_unwind_codes = seh_x64_size_prologue_data (c); /* ubyte:3 version, ubyte:5 flags. */ out_one ((flags << 3) | 1); /* Size of prologue. */ if (c->endprologue_addr) { exp.X_op = O_subtract; exp.X_add_symbol = c->endprologue_addr; exp.X_op_symbol = c->start_addr; exp.X_add_number = 0; emit_expr (&exp, 1); } else out_one (0); /* Number of slots (i.e. shorts) in the unwind codes array. */ if (count_unwind_codes > 255) as_fatal (_("too much unwind data in this .seh_proc")); out_one (count_unwind_codes); /* ubyte:4 frame-reg, ubyte:4 frame-reg-offset. */ /* Note that frameoff is already a multiple of 16, and therefore the offset is already both scaled and shifted into place. */ out_one (c->frameoff | c->framereg); seh_x64_write_prologue_data (c); /* We need to align prologue data. */ if (count_unwind_codes & 1) out_two (0); if (flags & (UNW_FLAG_EHANDLER | UNW_FLAG_UHANDLER)) { /* Force the use of segment-relative relocations instead of absolute valued expressions. Don't adjust for constants (e.g. NULL). */ if (c->handler.X_op == O_symbol) c->handler.X_op = O_symbol_rva; emit_expr (&c->handler, 4); } /* Handler data will be tacked in here by subsections. */ } /* Write out xdata for one function. */ static void write_function_xdata (seh_context *c) { segT save_seg = now_seg; int save_subseg = now_subseg; /* MIPS, SH, ARM don't have xdata. */ if (seh_get_target_kind () != seh_kind_x64) return; switch_xdata (c->subsection, c->code_seg); seh_x64_write_function_xdata (c); subseg_set (save_seg, save_subseg); } /* Write pdata section data for one function (arm). */ static void seh_arm_write_function_pdata (seh_context *c) { expressionS exp; unsigned int prol_len = 0, func_len = 0; unsigned int val; /* Start address of the function. */ exp.X_op = O_symbol; exp.X_add_symbol = c->start_addr; exp.X_add_number = 0; emit_expr (&exp, 4); exp.X_op = O_subtract; exp.X_add_symbol = c->end_addr; exp.X_op_symbol = c->start_addr; exp.X_add_number = 0; if (resolve_expression (&exp) && exp.X_op == O_constant) func_len = exp.X_add_number; else as_bad (_(".seh_endproc in a different section from .seh_proc")); if (c->endprologue_addr) { exp.X_op = O_subtract; exp.X_add_symbol = c->endprologue_addr; exp.X_op_symbol = c->start_addr; exp.X_add_number = 0; if (resolve_expression (&exp) && exp.X_op == O_constant) prol_len = exp.X_add_number; else as_bad (_(".seh_endprologue in a different section from .seh_proc")); } /* Both function and prologue are in units of instructions. */ func_len >>= (c->use_instruction_32 ? 2 : 1); prol_len >>= (c->use_instruction_32 ? 2 : 1); /* Assemble the second word of the pdata. */ val = prol_len & 0xff; val |= (func_len & 0x3fffff) << 8; if (c->use_instruction_32) val |= 0x40000000U; if (c->handler_written) val |= 0x80000000U; out_four (val); } /* Write out pdata for one function. */ static void write_function_pdata (seh_context *c) { expressionS exp; segT save_seg = now_seg; int save_subseg = now_subseg; memset (&exp, 0, sizeof (expressionS)); switch_pdata (c->code_seg); switch (seh_get_target_kind ()) { case seh_kind_x64: exp.X_op = O_symbol_rva; exp.X_add_number = 0; exp.X_add_symbol = c->start_addr; emit_expr (&exp, 4); exp.X_op = O_symbol_rva; exp.X_add_number = 0; exp.X_add_symbol = c->end_addr; emit_expr (&exp, 4); exp.X_op = O_symbol_rva; exp.X_add_number = 0; exp.X_add_symbol = c->xdata_addr; emit_expr (&exp, 4); break; case seh_kind_mips: exp.X_op = O_symbol; exp.X_add_number = 0; exp.X_add_symbol = c->start_addr; emit_expr (&exp, 4); exp.X_add_symbol = c->end_addr; emit_expr (&exp, 4); emit_expr (&c->handler, 4); emit_expr (&c->handler_data, 4); exp.X_add_symbol = (c->endprologue_addr ? c->endprologue_addr : c->start_addr); emit_expr (&exp, 4); break; case seh_kind_arm: seh_arm_write_function_pdata (c); break; default: abort (); } subseg_set (save_seg, save_subseg); }