[XEN v4 04/11] xen/drivers: ns16550: Use paddr_t for io_base/io_size

[Ayan Kumar Halder <ayan.kumar.halder@amd.com>]

io_base and io_size represent physical addresses. So they should use
paddr_t (instead of u64).

However in future, paddr_t may be defined as u32. So when typecasting
values from u64 to paddr_t, one should always check for any possible
truncation. If any truncation is discovered, Xen needs to return an
appropriate an error message for this.

Also moved the definition of PARSE_ERR_RET before its first usage.

Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
---
Changes from -
v1 - NA

v2 - 1. Extracted the patch from "[XEN v2 05/11] xen/arm: Use paddr_t instead of u64 for address/size"
into a separate patch of its own.

v3 - 1. Reduced the scope of pci_uart_io_base and uart_io_base definitions.
2. Instead of crashing, invoke PARSE_ERR_RET().
3. Moved PARSE_ERR_RET() so that it is defined before its first use.

 xen/drivers/char/ns16550.c | 41 ++++++++++++++++++++++++++------------
 1 file changed, 28 insertions(+), 13 deletions(-)

diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
index 092f6b9c4b..2e8a9cfb24 100644
--- a/xen/drivers/char/ns16550.c
+++ b/xen/drivers/char/ns16550.c
@@ -42,8 +42,8 @@
 
 static struct ns16550 {
     int baud, clock_hz, data_bits, parity, stop_bits, fifo_size, irq;
-    u64 io_base;   /* I/O port or memory-mapped I/O address. */
-    u64 io_size;
+    paddr_t io_base;   /* I/O port or memory-mapped I/O address. */
+    paddr_t io_size;
     int reg_shift; /* Bits to shift register offset by */
     int reg_width; /* Size of access to use, the registers
                     * themselves are still bytes */
@@ -1163,10 +1163,16 @@ static const struct ns16550_config __initconst uart_config[] =
     },
 };
 
+#define PARSE_ERR_RET(_f, _a...)             \
+    do {                                     \
+        printk( "ERROR: " _f "\n" , ## _a ); \
+        return false;                        \
+    } while ( 0 )
+
 static int __init
 pci_uart_config(struct ns16550 *uart, bool_t skip_amt, unsigned int idx)
 {
-    u64 orig_base = uart->io_base;
+    paddr_t orig_base = uart->io_base;
     unsigned int b, d, f, nextf, i;
 
     /* NB. Start at bus 1 to avoid AMT: a plug-in card cannot be on bus 0. */
@@ -1235,6 +1241,8 @@ pci_uart_config(struct ns16550 *uart, bool_t skip_amt, unsigned int idx)
                 /* MMIO based */
                 if ( param->mmio && !(bar & PCI_BASE_ADDRESS_SPACE_IO) )
                 {
+                    uint64_t pci_uart_io_base;
+
                     pci_conf_write32(PCI_SBDF(0, b, d, f),
                                      PCI_BASE_ADDRESS_0 + bar_idx*4, ~0u);
                     len = pci_conf_read32(PCI_SBDF(0, b, d, f),
@@ -1259,8 +1267,14 @@ pci_uart_config(struct ns16550 *uart, bool_t skip_amt, unsigned int idx)
                     else
                         size = len & PCI_BASE_ADDRESS_MEM_MASK;
 
-                    uart->io_base = ((u64)bar_64 << 32) |
-                                    (bar & PCI_BASE_ADDRESS_MEM_MASK);
+                    pci_uart_io_base = ((u64)bar_64 << 32) |
+                                        (bar & PCI_BASE_ADDRESS_MEM_MASK);
+
+                    /* Truncation detected while converting to paddr_t */
+                    if ( (pci_uart_io_base >> (PADDR_BITS - 1)) > 1 )
+                        PARSE_ERR_RET("Truncation detected for io_base address");
+
+                    uart->io_base = pci_uart_io_base;
                 }
                 /* IO based */
                 else if ( !param->mmio && (bar & PCI_BASE_ADDRESS_SPACE_IO) )
@@ -1456,13 +1470,6 @@ static enum __init serial_param_type get_token(char *token, char **value)
         return;                              \
     } while ( 0 )
 
-#define PARSE_ERR_RET(_f, _a...)             \
-    do {                                     \
-        printk( "ERROR: " _f "\n" , ## _a ); \
-        return false;                        \
-    } while ( 0 )
-
-
 static bool __init parse_positional(struct ns16550 *uart, char **str)
 {
     int baud;
@@ -1532,7 +1539,15 @@ static bool __init parse_positional(struct ns16550 *uart, char **str)
         else
 #endif
         {
-            uart->io_base = simple_strtoull(conf, &conf, 0);
+            uint64_t uart_io_base;
+
+            uart_io_base = simple_strtoull(conf, &conf, 0);
+
+            /* Truncation detected while converting to paddr_t */
+            if ( (uart_io_base >> (PADDR_BITS - 1)) > 1 )
+                PARSE_ERR_RET("Truncation detected for uart_io_base address");
+
+            uart->io_base = uart_io_base;
         }
     }
 
-- 
2.17.1