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Commit e505371d authored by Tom Lendacky's avatar Tom Lendacky Committed by Ingo Molnar
Browse files

x86/boot: Add early cmdline parsing for options with arguments 



Add a cmdline_find_option() function to look for cmdline options that
take arguments. The argument is returned in a supplied buffer and the
argument length (regardless of whether it fits in the supplied buffer)
is returned, with -1 indicating not found.

Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Toshimitsu Kani <toshi.kani@hpe.com>
Cc: kasan-dev@googlegroups.com
Cc: kvm@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-efi@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/36b5f97492a9745dce27682305f990fc20e5cf8a.1500319216.git.thomas.lendacky@amd.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 6ebcb060

arch/x86/include/asm/cmdline.h

+2 −0
Original line number Diff line number Diff line
@@ -2,5 +2,7 @@ 
#define _ASM_X86_CMDLINE_H



int cmdline_find_option_bool(const char *cmdline_ptr, const char *option);

int cmdline_find_option(const char *cmdline_ptr, const char *option,

			char *buffer, int bufsize);



#endif /* _ASM_X86_CMDLINE_H */

arch/x86/lib/cmdline.c

+105 −0
Original line number Diff line number Diff line
@@ -104,7 +104,112 @@ __cmdline_find_option_bool(const char *cmdline, int max_cmdline_size, 
	return 0;	/* Buffer overrun */

}



/*

 * Find a non-boolean option (i.e. option=argument). In accordance with

 * standard Linux practice, if this option is repeated, this returns the

 * last instance on the command line.

 *

 * @cmdline: the cmdline string

 * @max_cmdline_size: the maximum size of cmdline

 * @option: option string to look for

 * @buffer: memory buffer to return the option argument

 * @bufsize: size of the supplied memory buffer

 *

 * Returns the length of the argument (regardless of if it was

 * truncated to fit in the buffer), or -1 on not found.

 */

static int

__cmdline_find_option(const char *cmdline, int max_cmdline_size,

		      const char *option, char *buffer, int bufsize)

{

	char c;

	int pos = 0, len = -1;

	const char *opptr = NULL;

	char *bufptr = buffer;

	enum {

		st_wordstart = 0,	/* Start of word/after whitespace */

		st_wordcmp,	/* Comparing this word */

		st_wordskip,	/* Miscompare, skip */

		st_bufcpy,	/* Copying this to buffer */

	} state = st_wordstart;



	if (!cmdline)

		return -1;      /* No command line */



	/*

	 * This 'pos' check ensures we do not overrun

	 * a non-NULL-terminated 'cmdline'

	 */

	while (pos++ < max_cmdline_size) {

		c = *(char *)cmdline++;

		if (!c)

			break;



		switch (state) {

		case st_wordstart:

			if (myisspace(c))

				break;



			state = st_wordcmp;

			opptr = option;

			/* fall through */



		case st_wordcmp:

			if ((c == '=') && !*opptr) {

				/*

				 * We matched all the way to the end of the

				 * option we were looking for, prepare to

				 * copy the argument.

				 */

				len = 0;

				bufptr = buffer;

				state = st_bufcpy;

				break;

			} else if (c == *opptr++) {

				/*

				 * We are currently matching, so continue

				 * to the next character on the cmdline.

				 */

				break;

			}

			state = st_wordskip;

			/* fall through */



		case st_wordskip:

			if (myisspace(c))

				state = st_wordstart;

			break;



		case st_bufcpy:

			if (myisspace(c)) {

				state = st_wordstart;

			} else {

				/*

				 * Increment len, but don't overrun the

				 * supplied buffer and leave room for the

				 * NULL terminator.

				 */

				if (++len < bufsize)

					*bufptr++ = c;

			}

			break;

		}

	}



	if (bufsize)

		*bufptr = '\0';



	return len;

}



int cmdline_find_option_bool(const char *cmdline, const char *option)

{

	return __cmdline_find_option_bool(cmdline, COMMAND_LINE_SIZE, option);

}



int cmdline_find_option(const char *cmdline, const char *option, char *buffer,

			int bufsize)

{

	return __cmdline_find_option(cmdline, COMMAND_LINE_SIZE, option,

				     buffer, bufsize);

}