x86, boot: Carve out early cmdline parsing function

commit 1b1ded57a4f2f4420b4de7c395d1b841d8b3c41a upstream.

Carve out early cmdline parsing function into .../lib/cmdline.c so it
can be used by early code in the kernel proper as well.

Adapted from arch/x86/boot/cmdline.c.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1400525957-11525-2-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/x86/include/asm/cmdline.h b/arch/x86/include/asm/cmdline.h
new file mode 100644 (file)
index 0000000..e01f7f7
--- /dev/null
+++ b/arch/x86/include/asm/cmdline.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_X86_CMDLINE_H
+#define _ASM_X86_CMDLINE_H
+
+int cmdline_find_option_bool(const char *cmdline_ptr, const char *option);
+
+#endif /* _ASM_X86_CMDLINE_H */

diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index b00f678..2db5846 100644 (file)
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -16,7 +16,7 @@ clean-files := inat-tables.c
 
 obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o
 
-lib-y := delay.o
+lib-y := delay.o cmdline.o
 lib-y += thunk_$(BITS).o
 lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
 lib-y += memcpy_$(BITS).o

diff --git a/arch/x86/lib/cmdline.c b/arch/x86/lib/cmdline.c
new file mode 100644 (file)
index 0000000..422db00
--- /dev/null
+++ b/arch/x86/lib/cmdline.c
@@ -0,0 +1,84 @@
+/*
+ * This file is part of the Linux kernel, and is made available under
+ * the terms of the GNU General Public License version 2.
+ *
+ * Misc librarized functions for cmdline poking.
+ */
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <asm/setup.h>
+
+static inline int myisspace(u8 c)
+{
+       return c <= ' ';        /* Close enough approximation */
+}
+
+/**
+ * Find a boolean option (like quiet,noapic,nosmp....)
+ *
+ * @cmdline: the cmdline string
+ * @option: option string to look for
+ *
+ * Returns the position of that @option (starts counting with 1)
+ * or 0 on not found.
+ */
+int cmdline_find_option_bool(const char *cmdline, const char *option)
+{
+       char c;
+       int len, pos = 0, wstart = 0;
+       const char *opptr = NULL;
+       enum {
+               st_wordstart = 0,       /* Start of word/after whitespace */
+               st_wordcmp,     /* Comparing this word */
+               st_wordskip,    /* Miscompare, skip */
+       } state = st_wordstart;
+
+       if (!cmdline)
+               return -1;      /* No command line */
+
+       len = min_t(int, strlen(cmdline), COMMAND_LINE_SIZE);
+       if (!len)
+               return 0;
+
+       while (len--) {
+               c = *(char *)cmdline++;
+               pos++;
+
+               switch (state) {
+               case st_wordstart:
+                       if (!c)
+                               return 0;
+                       else if (myisspace(c))
+                               break;
+
+                       state = st_wordcmp;
+                       opptr = option;
+                       wstart = pos;
+                       /* fall through */
+
+               case st_wordcmp:
+                       if (!*opptr)
+                               if (!c || myisspace(c))
+                                       return wstart;
+                               else
+                                       state = st_wordskip;
+                       else if (!c)
+                               return 0;
+                       else if (c != *opptr++)
+                               state = st_wordskip;
+                       else if (!len)          /* last word and is matching */
+                               return wstart;
+                       break;
+
+               case st_wordskip:
+                       if (!c)
+                               return 0;
+                       else if (myisspace(c))
+                               state = st_wordstart;
+                       break;
+               }
+       }
+
+       return 0;       /* Buffer overrun */
+}