From 35b8bad0343a4afd9ad914e377e64bd02667c563 Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Sun, 19 Mar 2023 17:30:30 +0000
Subject: [PATCH] add --map-file option to map arbitrary files into physmem
This is useful e.g. in conjunction with the MTD PHRAM device on
embedded devices: a kernel can be booted with kexec and a root
filesystem entirely in RAM to see if it works before writing it
to flash.
---
kexec/kexec.8 | 14 ++++++++++++-
kexec/kexec.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++
kexec/kexec.h | 4 +++-
3 files changed, 73 insertions(+), 2 deletions(-)
diff --git a/kexec/kexec.8 b/kexec/kexec.8
index 3a344c5..3140ccb 100644
--- a/kexec/kexec.8
+++ b/kexec/kexec.8
@@ -143,10 +143,17 @@ into the current kernel.
.B \-p\ (\-\-load\-panic)
Load the new kernel for use on panic.
.TP
-.BI \-t\ (\-\-type= type )
+.BI \-m\ (\-\-type= type )
Specify that the new kernel is of this
.I type.
.TP
+.BI \-t\ (\-\-map-file= filename@addr )
+Read
+.I filename
+and arrange for it to be mapped into physical memory at the address
+.I addr.
+This option may be repeated if there are multiple files to map.
+.TP
.BI \-s\ (\-\-kexec-file-syscall)
Specify that the new KEXEC_FILE_LOAD syscall should be used exclusively.
.TP
@@ -206,6 +213,11 @@ Reuse initrd from first boot.
.BI \-\-print-ckr-size
Print crash kernel region size, if available.
+.PP
+Options taking an
+.I addr
+parameter will accept a memory address written in hexadecimal (with leading
+0x), or octal (leading 0), or decimal (no leading sigil).
.SH SUPPORTED KERNEL FILE TYPES AND OPTIONS
.B Beoboot-x86
diff --git a/kexec/kexec.c b/kexec/kexec.c
index 36bb2ad..c3b40a4 100644
--- a/kexec/kexec.c
+++ b/kexec/kexec.c
@@ -63,6 +63,13 @@ static unsigned long kexec_flags = 0;
static unsigned long kexec_file_flags = 0;
int kexec_debug = 0;
+#define MAPPED_FILES_MAX 10 /* arbitrary number */
+struct mapped_file {
+ const char *filename;
+ unsigned long long phys_address;
+} mapped_files[MAPPED_FILES_MAX] = { { .filename = NULL } };
+
+
void dbgprint_mem_range(const char *prefix, struct memory_range *mr, int nr_mr)
{
int i;
@@ -771,6 +778,19 @@ static int my_load(const char *type, int fileind, int argc, char **argv,
}
info.kexec_flags |= native_arch;
+ for(struct mapped_file *m = mapped_files; m->filename; m++) {
+ off_t file_size = 0;
+ char *buf = slurp_file(m->filename, &file_size);
+ add_buffer(&info,
+ buf, file_size, file_size, sizeof (void *),
+ m->phys_address,
+ mem_max, 1);
+ free(m->filename);
+ /* do we free() memory returned by slurp_file()?
+ * we don't know if it was mmaped, so maybe not
+ */
+ };
+
result = file_type[i].load(argc, argv, kernel_buf, kernel_size, &info);
if (result < 0) {
switch (result) {
@@ -1035,6 +1055,8 @@ void usage(void)
" load code into.\n"
" --mem-max=<addr> Specify the highest memory address to\n"
" load code into.\n"
+ " --map-file=<filename@addr> Map a file into memory for the\n"
+ " new kernel before kexec.\n"
" --reuseinitrd Reuse initrd from first boot.\n"
" --print-ckr-size Print crash kernel region size.\n"
" --load-preserve-context Load the new kernel and preserve\n"
@@ -1396,6 +1418,33 @@ static void print_crashkernel_region_size(void)
printf("%" PRIu64 "\n", (start != end) ? (end - start + 1) : 0UL);
}
+static int add_mapped_file(char * optarg)
+{
+ char *at = strchr(optarg, '@');
+ if(!at)
+ return 1;
+
+ struct mapped_file *m = mapped_files;
+ struct mapped_file *m_end = mapped_files +
+ ((sizeof mapped_files) / (sizeof mapped_files[0]));
+
+ while(m->filename && m < m_end)
+ m++;
+
+ if(m >= m_end)
+ return 1;
+
+ m->phys_address = strtoull(at + 1, NULL, 0);
+ if(m->phys_address == 0)
+ return 1;
+
+ m->filename = strndup(optarg, at - optarg);
+
+ (m+1)->filename = NULL;
+ return 0;
+}
+
+
int main(int argc, char *argv[])
{
int has_opt_load = 0;
@@ -1521,6 +1570,14 @@ int main(int argc, char *argv[])
kexec_file_flags |= KEXEC_FILE_ON_CRASH;
kexec_flags = KEXEC_ON_CRASH;
break;
+ case OPT_MAP_FILE:
+ if(add_mapped_file(optarg)) {
+ fprintf(stderr,
+ "Bad option value or too many mapped files in --mapped-file=%s\n",
+ optarg);
+ return 1;
+ }
+ break;
case OPT_MEM_MIN:
mem_min = strtoul(optarg, &endptr, 0);
if (*endptr) {
diff --git a/kexec/kexec.h b/kexec/kexec.h
index 0d820ad..78022b6 100644
--- a/kexec/kexec.h
+++ b/kexec/kexec.h
@@ -224,6 +224,7 @@ extern int file_types;
#define OPT_STATUS 'S'
#define OPT_MEM_MIN 256
#define OPT_MEM_MAX 257
+#define OPT_MAP_FILE 'm'
#define OPT_REUSE_INITRD 258
#define OPT_LOAD_PRESERVE_CONTEXT 259
#define OPT_LOAD_JUMP_BACK_HELPER 260
@@ -258,8 +259,9 @@ extern int file_types;
{ "debug", 0, 0, OPT_DEBUG }, \
{ "status", 0, 0, OPT_STATUS }, \
{ "print-ckr-size", 0, 0, OPT_PRINT_CKR_SIZE }, \
+ { "map-file", 1, 0, OPT_MAP_FILE }, \
-#define KEXEC_OPT_STR "h?vdfixyluet:pscaS"
+#define KEXEC_OPT_STR "h?vdfixyluet:pscaSm"
extern void dbgprint_mem_range(const char *prefix, struct memory_range *mr, int nr_mr);
extern void die(const char *fmt, ...)
--
2.38.1