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Date: Mon, 5 Mar 2018 19:24:55 -0500
From: Pavel Tatashin <pasha.tatashin@...cle.com>
To: steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
linux-kernel@...r.kernel.org, Alexander.Levin@...rosoft.com,
dan.j.williams@...el.com, sathyanarayanan.kuppuswamy@...el.com,
pankaj.laxminarayan.bharadiya@...el.com, akuster@...sta.com,
cminyard@...sta.com, pasha.tatashin@...cle.com,
gregkh@...uxfoundation.org, stable@...r.kernel.org
Subject: [PATCH 4.1 22/65] x86/boot: Add early cmdline parsing for options with arguments
From: Tom Lendacky <thomas.lendacky@....com>
commit e505371dd83963caae1a37ead9524e8d997341be upstream.
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: Tom Lendacky <thomas.lendacky@....com>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Alexander Potapenko <glider@...gle.com>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brijesh Singh <brijesh.singh@....com>
Cc: Dave Young <dyoung@...hat.com>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Jonathan Corbet <corbet@....net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc: Larry Woodman <lwoodman@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Matt Fleming <matt@...eblueprint.co.uk>
Cc: Michael S. Tsirkin <mst@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Toshimitsu Kani <toshi.kani@....com>
Cc: kasan-dev@...glegroups.com
Cc: kvm@...r.kernel.org
Cc: linux-arch@...r.kernel.org
Cc: linux-doc@...r.kernel.org
Cc: linux-efi@...r.kernel.org
Cc: linux-mm@...ck.org
Link: http://lkml.kernel.org/r/36b5f97492a9745dce27682305f990fc20e5cf8a.1500319216.git.thomas.lendacky@amd.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
(cherry picked from commit 0fa147b407478e73fe7a478677ff2b12bb824014)
Signed-off-by: Pavel Tatashin <pasha.tatashin@...cle.com>
---
arch/x86/include/asm/cmdline.h | 2 +
arch/x86/lib/cmdline.c | 105 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 107 insertions(+)
diff --git a/arch/x86/include/asm/cmdline.h b/arch/x86/include/asm/cmdline.h
index e01f7f7ccb0c..84ae170bc3d0 100644
--- a/arch/x86/include/asm/cmdline.h
+++ b/arch/x86/include/asm/cmdline.h
@@ -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 */
diff --git a/arch/x86/lib/cmdline.c b/arch/x86/lib/cmdline.c
index 422db000d727..a744506856b1 100644
--- a/arch/x86/lib/cmdline.c
+++ b/arch/x86/lib/cmdline.c
@@ -82,3 +82,108 @@ int cmdline_find_option_bool(const char *cmdline, const char *option)
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(const char *cmdline, const char *option, char *buffer,
+ int bufsize)
+{
+ return __cmdline_find_option(cmdline, COMMAND_LINE_SIZE, option,
+ buffer, bufsize);
+}
--
2.16.2
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