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[nasm:master] Add option to allow 64-bit code in any output format
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From: nasm-bot f. K. S. O. <bir...@an...> - 2016-01-26 20:36:20
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Commit-ID: 3c72a1b3b301909548474e0d74b64f6d1383131f Gitweb: http://repo.or.cz/w/nasm.git?a=commitdiff;h=3c72a1b3b301909548474e0d74b64f6d1383131f Author: Knut St. Osmundsen <bir...@an...> AuthorDate: Tue, 10 Nov 2015 22:07:20 +0100 Committer: H. Peter Anvin <hp...@zy...> CommitDate: Tue, 26 Jan 2016 12:34:41 -0800 Add option to allow 64-bit code in any output format Add the option --allow-64-bit to permit the generation of 64-bit code even for a 16/32-bit output format. Using NASM to do some boot strapping code and ran into trouble when trying to emit a few 64-bit instructions in the OMF object file doing the mode switching. While I can see how the "error: obj output format does not support 64-bit code" message can be a useful reality check for application programmers, it prevents low-level programmers from doing what they want. It if was just a harmless warning, it wouldn't be so bad, but it turns BITS 64 into BITS 16. The main trick to mixing 64-bit code into OMF and other 32-bit output formats is to avoid 64-bit sized fixups, which normally isn't too hard. [hpa: shortened the option name to --allow-64-bit, minor code cleanups] Signed-off-by: Knut St. Osmundsen <bir...@an...> Signed-off-by: H. Peter Anvin <hp...@zy...> --- doc/nasmdoc.src | 16 +++++++++++++--- nasm.c | 37 +++++++++++++++++++++++++------------ 2 files changed, 38 insertions(+), 15 deletions(-) diff --git a/doc/nasmdoc.src b/doc/nasmdoc.src index e468248..ec0cfcc 100644 --- a/doc/nasmdoc.src +++ b/doc/nasmdoc.src @@ -1,6 +1,6 @@ \# -------------------------------------------------------------------------- \# -\# Copyright 1996-2014 The NASM Authors - All Rights Reserved +\# Copyright 1996-2016 The NASM Authors - All Rights Reserved \# See the file AUTHORS included with the NASM distribution for \# the specific copyright holders. \# @@ -1006,8 +1006,18 @@ is indicated by an asterisk. For example: The \c{--prefix} and \c{--postfix} options prepend or append (respectively) the given argument to all \c{global} or \c{extern} variables. E.g. \c{--prefix _} will prepend the -underscore to all global and external variables, as C sometimes -(but not always) likes it. +underscore to all global and external variables, as C requires it in +some, but not all, system calling conventions. + + +\S{opt-allow64bit} The \i\c{--allow-64-bit} Option. + +The \c{--allow-64-bit} option allows using 64-bit instructions in a +32-bit or 16-bit output format. This is useful in a few situations, +such as when writing code switching from 32-bit to 64-bit mode and +linking into a 32-bit module. However, it is important to be aware of +the restriction the output format poses on you in terms of +relocations. Use with caution! \S{nasmenv} The \i\c{NASMENV} \i{Environment} Variable diff --git a/nasm.c b/nasm.c index 8557b4d..17ee553 100644 --- a/nasm.c +++ b/nasm.c @@ -1,6 +1,6 @@ /* ----------------------------------------------------------------------- * * - * Copyright 1996-2013 The NASM Authors - All Rights Reserved + * Copyright 1996-2016 The NASM Authors - All Rights Reserved * See the file AUTHORS included with the NASM distribution for * the specific copyright holders. * @@ -88,6 +88,7 @@ static int using_debug_info, opt_verbose_info; bool tasm_compatible_mode = false; int pass0, passn; int maxbits = 0; +static bool allow_64_bit = false; int globalrel = 0; int globalbnd = 0; @@ -614,11 +615,15 @@ struct textargs { int value; }; -#define OPT_PREFIX 0 -#define OPT_POSTFIX 1 +enum text_options { + OPT_PREFIX, + OPT_POSTFIX, + OPT_ALLOW_64_BIT +}; struct textargs textopts[] = { {"prefix", OPT_PREFIX}, {"postfix", OPT_POSTFIX}, + {"allow-64-bit", OPT_ALLOW_64_BIT}, {NULL, 0} }; @@ -804,7 +809,10 @@ static bool process_arg(char *p, char *q) " -h show invocation summary and exit\n\n" "--prefix,--postfix\n" " this options prepend or append the given argument to all\n" - " extern and global variables\n\n" + " extern and global variables\n" + "--allow-64-bit\n" + " do not restrict 64-bit code to 64-bit capable output\n" + " formats (use with care, no complaining)\n\n" "Warnings:\n"); for (i = 0; i <= ERR_WARN_MAX; i++) printf(" %-23s %s (default %s)\n", @@ -959,18 +967,23 @@ set_warning: advance = 1, param = q; } - if (s == OPT_PREFIX) { - strncpy(lprefix, param, PREFIX_MAX - 1); - lprefix[PREFIX_MAX - 1] = 0; + switch (s) { + case OPT_PREFIX: + strlcpy(lprefix, param, PREFIX_MAX); break; - } - if (s == OPT_POSTFIX) { - strncpy(lpostfix, param, POSTFIX_MAX - 1); - lpostfix[POSTFIX_MAX - 1] = 0; + case OPT_POSTFIX: + strlcpy(lpostfix, param, POSTFIX_MAX); + break; + default: + nasm_error(ERR_PANIC | ERR_NOFILE, + "internal error"); break; } break; } + case OPT_ALLOW_64_BIT: + allow_64_bit = true; + break; default: { nasm_error(ERR_NONFATAL | ERR_NOFILE | ERR_USAGE, @@ -2088,7 +2101,7 @@ static int get_bits(char *value) "cannot specify 64-bit segment on processor below an x86-64"); i = 16; } - if (i != maxbits) { + if (i != maxbits && !allow_64_bit) { nasm_error(ERR_NONFATAL, "%s output format does not support 64-bit code", ofmt->shortname); |
