libpayload: Cache physical location of strings

In the presence of self-relocating payloads, it's safer to keep
physical addresses in `libsysinfo`. This updates the remaining
pointers that are not consumed by libpayload code, all of them
strings.

Also update the comment that `libsysinfo` only containts physical
addresses.

Change-Id: I9d095c826b00d621201c34b329fb9b5beb1ec794
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43581
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>

2 files changed, 21 insertions, 17 deletions

diff --git a/payloads/libpayload/include/sysinfo.h b/payloads/libpayload/include/sysinfo.h
index a1b0545074..fe3d3304c4 100644
--- a/payloads/libpayload/include/sysinfo.h
+++ b/payloads/libpayload/include/sysinfo.h
@@ -42,10 +42,11 @@
 #include <coreboot_tables.h>
 
 /*
- * All pointers in here shall be virtual.
+ * This is a collection of information and pointers gathered
+ * mostly from the coreboot table.
  *
- * If a relocation happens after the last call to lib_get_sysinfo(),
- * it is up to the user to call lib_get_sysinfo() again.
+ * We do not store virtual pointers in here to avoid problems
+ * with self-relocating payloads.
  */
 struct sysinfo_t {
 	unsigned int cpu_khz;
@@ -68,18 +69,18 @@ struct sysinfo_t {
 	u32 vbnv_start;
 	u32 vbnv_size;
 
-	char *version;
-	char *extra_version;
-	char *build;
-	char *compile_time;
-	char *compile_by;
-	char *compile_host;
-	char *compile_domain;
-	char *compiler;
-	char *linker;
-	char *assembler;
+	uintptr_t version;
+	uintptr_t extra_version;
+	uintptr_t build;
+	uintptr_t compile_time;
+	uintptr_t compile_by;
+	uintptr_t compile_host;
+	uintptr_t compile_domain;
+	uintptr_t compiler;
+	uintptr_t linker;
+	uintptr_t assembler;
 
-	char *cb_version;
+	uintptr_t cb_version;
 
 	struct cb_framebuffer framebuffer;
 
@@ -87,7 +88,7 @@ struct sysinfo_t {
 	struct cb_gpio gpios[SYSINFO_MAX_GPIOS];
 	int num_macs;
 	struct mac_address macs[SYSINFO_MAX_MACS];
-	char *serialno;
+	uintptr_t serialno;
 
 	unsigned long *mbtable; /** Pointer to the multiboot table */
 
diff --git a/payloads/libpayload/libc/coreboot.c b/payloads/libpayload/libc/coreboot.c
index b34f2c582f..c48b6cffd8 100644
--- a/payloads/libpayload/libc/coreboot.c
+++ b/payloads/libpayload/libc/coreboot.c
@@ -184,9 +184,12 @@ static void cb_parse_framebuffer(void *ptr, struct sysinfo_t *info)
 }
 #endif
 
-static void cb_parse_string(unsigned char *ptr, char **info)
+static void cb_parse_string(const void *const ptr, uintptr_t *const info)
 {
-	*info = (char *)((struct cb_string *)ptr)->string;
+	/* ptr is already virtual (str->string just an offset to that),
+	   but we want to keep physical addresses */
+	const struct cb_string *const str = ptr;
+	*info = virt_to_phys(str->string);
 }
 
 static void cb_parse_wifi_calibration(void *ptr, struct sysinfo_t *info)