Access the device tree blob via copyin/copyout.

The code previously assumed that copyin/copyout did no
address translation and that the device tree blob could
be manipulated in-place (with only a few adjustments for
the ELF loader offset).  This isn't possible on all platforms,
so the revised code uses copyout() to copy the device tree
blob into a heap-allocated buffer and then updates the
device tree with copyout().  This isn't ideal, since it
bloats the loader memory usage, but seems the only feasible
approach (short of rewriting all of the fdt manipulation
routines).

1 files changed, 64 insertions, 39 deletions

diff --git a/sys/boot/fdt/fdt_loader_cmd.c b/sys/boot/fdt/fdt_loader_cmd.c
index 6e713b6..b52d92f 100644
--- a/sys/boot/fdt/fdt_loader_cmd.c
+++ b/sys/boot/fdt/fdt_loader_cmd.c
@@ -57,11 +57,17 @@ __FBSDID("$FreeBSD$");
 #define STR(number) #number
 #define STRINGIFY(number) STR(number)
 
-#define COPYOUT(s,d,l)	archsw.arch_copyout((vm_offset_t)(s), d, l)
+#define COPYOUT(s,d,l)	archsw.arch_copyout(s, d, l)
+#define COPYIN(s,d,l)	archsw.arch_copyin(s, d, l)
 
 #define FDT_STATIC_DTB_SYMBOL	"fdt_static_dtb"
 
+/* Local copy of FDT */
 static struct fdt_header *fdtp = NULL;
+/* Size of FDT blob */
+static size_t fdtp_size = 0;
+/* Location of FDT in kernel or module */
+static vm_offset_t fdtp_va = 0;
 
 static int fdt_cmd_nyi(int argc, char *argv[]);
 
@@ -98,21 +104,19 @@ static const struct cmdtab commands[] = {
 static char cwd[FDT_CWD_LEN] = "/";
 
 static vm_offset_t
-fdt_find_static_dtb(void)
+fdt_find_static_dtb()
 {
+	Elf_Dyn dyn;
 	Elf_Sym sym;
-	vm_offset_t dyntab, esym;
+	vm_offset_t dyntab, esym, strtab, symtab, fdt_start;
 	uint64_t offs;
 	struct preloaded_file *kfp;
 	struct file_metadata *md;
-	Elf_Sym *symtab;
-	Elf_Dyn *dyn;
-	char *strtab, *strp;
-	int i, sym_count;
+	char *strp;
+	int sym_count;
 
-	symtab = NULL;
-	dyntab = esym = 0;
-	strtab = strp = NULL;
+	symtab = strtab = dyntab = esym = 0;
+	strp = NULL;
 
 	offs = __elfN(relocation_offset);
 
@@ -123,28 +127,29 @@ fdt_find_static_dtb(void)
 	md = file_findmetadata(kfp, MODINFOMD_ESYM);
 	if (md == NULL)
 		return (0);
-	COPYOUT(md->md_data, &esym, sizeof(esym));
+	bcopy(md->md_data, &esym, sizeof(esym));
+	// esym is already offset
 
 	md = file_findmetadata(kfp, MODINFOMD_DYNAMIC);
 	if (md == NULL)
 		return (0);
-	COPYOUT(md->md_data, &dyntab, sizeof(dyntab));
-
+	bcopy(md->md_data, &dyntab, sizeof(dyntab));
 	dyntab += offs;
 
 	/* Locate STRTAB and DYNTAB */
-	for (dyn = (Elf_Dyn *)dyntab; dyn->d_tag != DT_NULL; dyn++) {
-		if (dyn->d_tag == DT_STRTAB) {
-			strtab = (char *)(uintptr_t)(dyn->d_un.d_ptr + offs);
-			continue;
-		} else if (dyn->d_tag == DT_SYMTAB) {
-			symtab = (Elf_Sym *)(uintptr_t)
-			    (dyn->d_un.d_ptr + offs);
-			continue;
+	for (;;) {
+		COPYOUT(dyntab, &dyn, sizeof(dyn));
+		if (dyn.d_tag == DT_STRTAB) {
+			strtab = (vm_offset_t)(dyn.d_un.d_ptr) + offs;
+		} else if (dyn.d_tag == DT_SYMTAB) {
+			symtab = (vm_offset_t)(dyn.d_un.d_ptr) + offs;
+		} else if (dyn.d_tag == DT_NULL) {
+			break;
 		}
+		dyntab += sizeof(dyn);
 	}
 
-	if (symtab == NULL || strtab == NULL) {
+	if (symtab == 0 || strtab == 0) {
 		/*
 		 * No symtab? No strtab? That should not happen here,
 		 * and should have been verified during __elfN(loadimage).
@@ -153,7 +158,7 @@ fdt_find_static_dtb(void)
 		return (0);
 	}
 
-	sym_count = (int)((Elf_Sym *)esym - symtab) / sizeof(Elf_Sym);
+	sym_count = (int)(esym - symtab) / sizeof(Elf_Sym);
 
 	/*
 	 * The most efficent way to find a symbol would be to calculate a
@@ -165,26 +170,27 @@ fdt_find_static_dtb(void)
 	 * we are eliminating symbols type of which is not STT_NOTYPE, or(and)
 	 * those which binding attribute is not STB_GLOBAL.
 	 */
-	for (i = 0; i < sym_count; i++) {
-		COPYOUT(symtab + i, &sym, sizeof(sym));
+	fdt_start = 0;
+	while (sym_count > 0 && fdt_start == 0) {
+		COPYOUT(symtab, &sym, sizeof(sym));
+		symtab += sizeof(sym);
+		--sym_count;
 		if (ELF_ST_BIND(sym.st_info) != STB_GLOBAL ||
 		    ELF_ST_TYPE(sym.st_info) != STT_NOTYPE)
 			continue;
-
-		strp = strdupout((vm_offset_t)(strtab + sym.st_name));
-		if (strcmp(strp, FDT_STATIC_DTB_SYMBOL) == 0) {
-			/* Found a match ! */
-			free(strp);
-			return ((vm_offset_t)(sym.st_value + offs));
-		}
+		strp = strdupout(strtab + sym.st_name);
+		if (strcmp(strp, FDT_STATIC_DTB_SYMBOL) == 0)
+			fdt_start = (vm_offset_t)sym.st_value + offs;
 		free(strp);
 	}
-	return (0);
+	printf("fdt_start: 0x%08jX\n", (intmax_t)fdt_start);
+	return (fdt_start);
 }
 
 static int
 fdt_setup_fdtp()
 {
+	struct fdt_header header;
 	struct preloaded_file *bfp;
 	int err;
 
@@ -193,15 +199,26 @@ fdt_setup_fdtp()
 	 */
 	bfp = file_findfile(NULL, "dtb");
 	if (bfp == NULL) {
-		if ((fdtp = (struct fdt_header *)fdt_find_static_dtb()) == 0) {
+		if ((fdtp_va = fdt_find_static_dtb()) == 0) {
 			command_errmsg = "no device tree blob found!";
+			printf("%s\n", command_errmsg);
 			return (CMD_ERROR);
 		}
 	} else {
 		/* Dynamic blob has precedence over static. */
-		fdtp = (struct fdt_header *)bfp->f_addr;
+		fdtp_va = bfp->f_addr;
 	}
 
+	COPYOUT(fdtp_va, &header, sizeof(header));
+	fdtp_size = fdt_totalsize(&header);
+	fdtp = malloc(fdtp_size);
+	if (fdtp == NULL) {
+		command_errmsg = "can't allocate memory for device tree copy";
+			printf("%s\n", command_errmsg);
+		return (CMD_ERROR);
+	}
+	COPYOUT(fdtp_va, fdtp, fdtp_size);
+
 	/*
 	 * Validate the blob.
 	 */
@@ -547,7 +564,7 @@ fixup_stdout(const char *env)
 /*
  * Locate the blob, fix it up and return its location.
  */
-void *
+vm_offset_t
 fdt_fixup(void)
 {
 	const char *env;
@@ -563,7 +580,7 @@ fdt_fixup(void)
 	err = fdt_setup_fdtp();
 	if (err) {
 		sprintf(command_errbuf, "No valid device tree blob found!");
-		return (NULL);
+		return (0);
 	}
 
 	/* Create /chosen node (if not exists) */
@@ -618,7 +635,9 @@ fdt_fixup(void)
 	fdt_setprop(fdtp, chosen, "fixup-applied", NULL, 0);
 
 success:
-	return (fdtp);
+	/* Overwrite the FDT with the fixed version. */
+	COPYIN(fdtp, fdtp_va, fdtp_size);
+	return (fdtp_va);
 }
 
 int
@@ -636,7 +655,7 @@ command_fdt_internal(int argc, char *argv[])
 	/*
 	 * Check if uboot env vars were parsed already. If not, do it now.
 	 */
-	if (fdt_fixup() == NULL)
+	if (fdt_fixup() == 0)
 		return (CMD_ERROR);
 
 	/*
@@ -1153,6 +1172,8 @@ fdt_modprop(int nodeoff, char *propname, void *value, char mode)
 		else
 			sprintf(command_errbuf,
 			    "Could not add/modify property!\n");
+	} else {
+		COPYIN(fdtp, fdtp_va, fdtp_size);
 	}
 	return (rv);
 }
@@ -1373,6 +1394,8 @@ fdt_cmd_rm(int argc, char *argv[])
 	if (rv) {
 		sprintf(command_errbuf, "could not delete node");
 		return (CMD_ERROR);
+	} else {
+		COPYIN(fdtp, fdtp_va, fdtp_size);
 	}
 	return (CMD_OK);
 }
@@ -1403,6 +1426,8 @@ fdt_cmd_mknode(int argc, char *argv[])
 			sprintf(command_errbuf,
 			    "Could not add node!\n");
 		return (CMD_ERROR);
+	} else {
+		COPYIN(fdtp, fdtp_va, fdtp_size);
 	}
 	return (CMD_OK);
 }