kexec jump support for kexec-tools

To support memory backup/restore an option named
--load-preserve-context is added to kexec. When it is specified
toggether with --mem-max, most segments for crash dump support are
loaded, and the memory range between mem_min to mem_max which has no
segments loaded are loaded as backup segments. To support jump back
from kexeced, options named --load-jump-back-helper and --entry are
added to load a helper image with specified entry to jump back.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

4 files changed, 49 insertions, 7 deletions

diff --git a/purgatory/arch/i386/purgatory-x86.c b/purgatory/arch/i386/purgatory-x86.c
index 4d2c5c7..030b465 100644
--- a/purgatory/arch/i386/purgatory-x86.c
+++ b/purgatory/arch/i386/purgatory-x86.c
@@ -31,6 +31,8 @@ uint8_t reset_vga = 0;
 uint8_t legacy_timer = 0;
 uint8_t legacy_pic   = 0;
 uint8_t panic_kernel = 0;
+unsigned long jump_back_entry = 0;
+char *cmdline_end = 0;
 
 void setup_arch(void)
 {
@@ -40,8 +42,18 @@ void setup_arch(void)
 	/* if (legacy_timer) x86_setup_legacy_timer(); */
 }
 
+extern void x86_setup_jump_back_entry();
+
 /* This function can be used to execute after the SHA256 verification. */
 void post_verification_setup_arch(void)
 {
-	if (panic_kernel)   crashdump_backup_memory();
+	if (panic_kernel)    crashdump_backup_memory();
+	if (jump_back_entry) x86_setup_jump_back_entry();
+}
+
+void x86_setup_jump_back_entry()
+{
+	if (cmdline_end)
+		sprintf(cmdline_end, " kexec_jump_back_entry=0x%x",
+			jump_back_entry);
 }
diff --git a/purgatory/arch/i386/setup-x86.S b/purgatory/arch/i386/setup-x86.S
index f0719d4..201bb2c 100644
--- a/purgatory/arch/i386/setup-x86.S
+++ b/purgatory/arch/i386/setup-x86.S
@@ -41,6 +41,9 @@ purgatory_start:
 	ljmp	$0x10,$1f
 1:		
 
+	movl	0(%esp), %eax
+	movl	%eax, jump_back_entry
+
 	/* Setup a stack */
 	movl	$lstack_end, %esp
 
diff --git a/purgatory/include/purgatory.h b/purgatory/include/purgatory.h
index 79ed5bf..ed50dc4 100644
--- a/purgatory/include/purgatory.h
+++ b/purgatory/include/purgatory.h
@@ -2,6 +2,7 @@
 #define PURGATORY_H
 
 void putchar(int ch);
+void sprintf(char *buffer, const char *fmt, ...);
 void printf(const char *fmt, ...);
 void setup_arch(void);
 void post_verification_setup_arch(void);
diff --git a/purgatory/printf.c b/purgatory/printf.c
index 962683d..9a78243 100644
--- a/purgatory/printf.c
+++ b/purgatory/printf.c
@@ -33,19 +33,23 @@ PRINTF and friends
 		%s	- string
 	Note: width specification not supported
 **************************************************************************/
-void printf(const char *fmt, ...)
+void vsprintf(char *buffer, const char *fmt, va_list args)
 {
-	va_list args;
 	char *p;
-	va_start(args, fmt);
 	for ( ; *fmt != '\0'; ++fmt) {
 		if (*fmt != '%') {
-			putchar(*fmt);
+			if (buffer)
+				*buffer++ = *fmt;
+			else
+				putchar(*fmt);
 			continue;
 		}
 		if (*++fmt == 's') {
 			for(p = va_arg(args, char *); *p != '\0'; p++) 
-				putchar(*p);
+				if (buffer)
+					*buffer++ = *p;
+				else
+					putchar(*p);
 		}
 		else {	/* Length of item is bounded */
 			char tmp[40], *q = tmp;
@@ -121,8 +125,30 @@ void printf(const char *fmt, ...)
 				*q++ = *fmt;
 			/* now output the saved string */
 			for (p = tmp; p < q; ++p)
-				putchar(*p);
+				if (buffer)
+					*buffer++ = *p;
+				else
+					putchar(*p);
 		}
 	}
+	if (buffer)
+		*buffer = '\0';
+}
+
+void sprintf(char *buffer, const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	vsprintf(buffer, fmt, args);
+	va_end(args);
+}
+
+void printf(const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	vsprintf(0, fmt, args);
 	va_end(args);
 }