[coreboot-gerrit] Change in coreboot[master]: libpayload: Make 8250 UART driver relocation safe

[Nico Huber (Code Review)]

Nico Huber has submitted this change. ( https://review.coreboot.org/c/coreboot/+/37513 )

Change subject: libpayload: Make 8250 UART driver relocation safe
......................................................................

libpayload: Make 8250 UART driver relocation safe

`lib_sysinfo->serial` is a virtual pointer into coreboot tables.
It's not valid across relocation. Accessing the wrong value during
relocation of FILO resulted in a hang with DEBUG_SEGMENT and UART
console enabled. Work around that by caching the whole table entry
locally.

An alternative would be to revise `sysinfo`, to contain no virtual
pointers to anything outside the payload.

Change-Id: I03adaf57b83a177316d7778f7e06df8eb6f9158e
Signed-off-by: Nico Huber 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37513
Tested-by: build bot (Jenkins) 
Reviewed-by: Reto Buerki 
Reviewed-by: Angel Pons 
---
M payloads/libpayload/drivers/serial/8250.c
1 file changed, 10 insertions(+), 11 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Reto Buerki: Looks good to me, but someone else must approve
  Angel Pons: Looks good to me, approved

diff --git a/payloads/libpayload/drivers/serial/8250.c b/payloads/libpayload/drivers/serial/8250.c
index 9502d4b..4a7cc01 100644
--- a/payloads/libpayload/drivers/serial/8250.c
+++ b/payloads/libpayload/drivers/serial/8250.c
@@ -31,7 +31,9 @@
 #include <libpayload-config.h>
 #include <libpayload.h>

-#define IOBASE lib_sysinfo.serial->baseaddr
+static struct cb_serial cb_serial;
+
+#define IOBASE cb_serial.baseaddr
 #define MEMBASE (phys_to_virt(IOBASE))

static int serial_hardware_is_present = 0;
@@ -39,14 +41,14 @@

static uint8_t serial_read_reg(int offset)
 {
-	offset *= lib_sysinfo.serial->regwidth;
+	offset *= cb_serial.regwidth;

#if CONFIG(LP_IO_ADDRESS_SPACE)
    if (!serial_is_mem_mapped)
    	return inb(IOBASE + offset);
    else
 #endif
-		if (lib_sysinfo.serial->regwidth == 4)
+		if (cb_serial.regwidth == 4)
    		return readl(MEMBASE + offset) & 0xff;
    	else
    		return readb(MEMBASE + offset);
@@ -54,14 +56,14 @@

static void serial_write_reg(uint8_t val, int offset)
 {
-	offset *= lib_sysinfo.serial->regwidth;
+	offset *= cb_serial.regwidth;

#if CONFIG(LP_IO_ADDRESS_SPACE)
    if (!serial_is_mem_mapped)
    	outb(val, IOBASE + offset);
    else
 #endif
-		if (lib_sysinfo.serial->regwidth == 4)
+		if (cb_serial.regwidth == 4)
    		writel(val & 0xff, MEMBASE + offset);
    	else
    		writeb(val, MEMBASE + offset);
@@ -108,11 +110,7 @@

void serial_init(void)
 {
-	if (!lib_sysinfo.serial)
-		return;
-
-	serial_is_mem_mapped =
-		(lib_sysinfo.serial->type == CB_SERIAL_TYPE_MEMORY_MAPPED);
+	serial_is_mem_mapped = (cb_serial.type == CB_SERIAL_TYPE_MEMORY_MAPPED);

if (!serial_is_mem_mapped) {
 #if CONFIG(LP_IO_ADDRESS_SPACE)
@@ -130,15 +128,16 @@
 #if CONFIG(LP_SERIAL_SET_SPEED)
    serial_hardware_init(CONFIG_LP_SERIAL_BAUD_RATE, 8, 0, 1);
 #endif
+	serial_hardware_is_present = 1;
 }

void serial_console_init(void)
 {
    if (!lib_sysinfo.serial)
    	return;
+	cb_serial = *lib_sysinfo.serial;

serial_init();
-	serial_hardware_is_present = 1;

console_add_input_driver(&consin);
    console_add_output_driver(&consout);