Merge tag 'x86-urgent-2026-07-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:

 - Reject too long acpi_rsdp= boot parameter values (Thorsten Blum)

 - Validate console=uart8250 baud rate to fix early boot hang (Thorsten
   Blum)

 - Remove dead Makefile rule (Ethan Nelson-Moore)

* tag 'x86-urgent-2026-07-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/boot: Validate console=uart8250 baud rate to fix early boot hang
  x86/boot: Reject too long acpi_rsdp= values
  x86/cpu: Remove Makefile rule for removed UMC CPU support

Author: torvalds

arch/x86/boot/compressed/acpi.c

@@ -184,10 +184,15 @@ static unsigned long get_cmdline_acpi_rsdp(void)
 	char val[MAX_ADDR_LEN] = { };
 	int ret;
 
-	ret = cmdline_find_option("acpi_rsdp", val, MAX_ADDR_LEN);
+	ret = cmdline_find_option("acpi_rsdp", val, sizeof(val));
 	if (ret < 0)
 		return 0;
 
+	if (ret >= sizeof(val)) {
+		warn("acpi_rsdp= value too long; ignoring");
+		return 0;
+	}
+
 	if (boot_kstrtoul(val, 16, &addr))
 		return 0;
 #endif

arch/x86/boot/early_serial_console.c

@@ -117,7 +117,7 @@ static unsigned int probe_baud(int port)
 static void parse_console_uart8250(void)
 {
 	char optstr[64], *options;
-	int baud = DEFAULT_BAUD;
+	int baud;
 	int port = 0;
 
 	/*
@@ -136,10 +136,13 @@ static void parse_console_uart8250(void)
 	else
 		return;
 
-	if (options && (options[0] == ','))
-		baud = simple_strtoull(options + 1, &options, 0);
-	else
+	if (options && (options[0] == ',')) {
+		baud = simple_strtoull(options + 1, NULL, 0);
+		if (!baud)
+			baud = DEFAULT_BAUD;
+	} else {
 		baud = probe_baud(port);
+	}
 
 	if (port)
 		early_serial_init(port, baud);

arch/x86/kernel/cpu/Makefile

@@ -46,7 +46,6 @@ obj-$(CONFIG_CPU_SUP_HYGON)		+= hygon.o
 obj-$(CONFIG_CPU_SUP_CYRIX_32)		+= cyrix.o
 obj-$(CONFIG_CPU_SUP_CENTAUR)		+= centaur.o
 obj-$(CONFIG_CPU_SUP_TRANSMETA_32)	+= transmeta.o
-obj-$(CONFIG_CPU_SUP_UMC_32)		+= umc.o
 obj-$(CONFIG_CPU_SUP_ZHAOXIN)		+= zhaoxin.o
 obj-$(CONFIG_CPU_SUP_VORTEX_32)		+= vortex.o