[RFC/PATCH 1/17][kexec-tools-1.101] vmlinux parameter segmentstomping fix

[Vivek Goyal]

During loading of panic kernel(vmlinux), it was found that on some systems,
parameter segment was being stomped over by kernel. This was resulting in 
corruption of e820 memory map and leading to boot memory allocator
initialization failures while booting into new kernel. This patch fixes the
problem by loading the parameter segment beyond alrady loaded kernel image
and setup code. A 64K buffer has been provided to avoid any stomping by
kernel.

Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---

 kexec-tools-1.101-root/kexec/arch/i386/kexec-elf-x86.c |   16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diff -puN kexec/arch/i386/kexec-elf-x86.c~kexec-tools-vmlinux-parameter-segment-stomping-fix kexec/arch/i386/kexec-elf-x86.c
--- kexec-tools-1.101/kexec/arch/i386/kexec-elf-x86.c~kexec-tools-vmlinux-parameter-segment-stomping-fix	2005-03-21 16:43:50.000000000 +0530
+++ kexec-tools-1.101-root/kexec/arch/i386/kexec-elf-x86.c	2005-03-21 16:43:50.000000000 +0530
@@ -199,15 +199,27 @@ int elf_x86_load(int argc, char **argv, 
 	}
 	else if (arg_style == ARG_STYLE_LINUX) {
 		struct x86_linux_faked_param_header *hdr;
-		unsigned long param_base;
+		unsigned long param_base, min_param_base = 0;
 		const unsigned char *ramdisk_buf;
 		off_t ramdisk_length;
 		struct entry32_regs regs;
+		int i;
 
 		/* Get the linux parameter header */
 		hdr = xmalloc(sizeof(*hdr));
+		/* Add parameter segment beyond already loaded segments, so that
+		 * it does not get stomped by kernel. */
+		for (i = 0; i < info->nr_segments; i++) {
+			unsigned long temp;
+			temp = (unsigned long) info->segment[i].mem +
+				info->segment[i].memsz;
+			if (temp > min_param_base)
+				min_param_base =  temp;
+		}
+		/* 64K of buffer to keep enough distance from kernel. */
+		min_param_base += 64*1024;
 		param_base = add_buffer(info, hdr, sizeof(*hdr), sizeof(*hdr),
-			16, 0, max_addr, 1);
+			16, min_param_base, max_addr, 1);
 
 		/* Initialize the parameter header */
 		memset(hdr, 0, sizeof(*hdr));
_