RISC-V Updates for the 4.21 Merge Window, Part 1

We don't have many patches for this merge window, probably because
 everything has been a bit busy with the holidays and conferences.  The
 only big user-visible change is to move over to an SBI-based earlycon
 instead of our arch-specific early printk support.
 
 The only outstanding patch set I know of is the audit patch set, which
 I've managed to make a mess of and will attempt to clean up.
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Merge tag 'riscv-for-linus-4.21-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux

Pull RISC-V updates from Palmer Dabbelt:
 "We don't have many patches for this merge window, probably because
  everything has been a bit busy with the holidays and conferences. The
  only big user-visible change is to move over to an SBI-based earlycon
  instead of our arch-specific early printk support.

  The only outstanding patch set I know of is the audit patch set, which
  I've managed to make a mess of and will attempt to clean up"

* tag 'riscv-for-linus-4.21-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux:
  RISC-V: Select GENERIC_SCHED_CLOCK for clocksource drivers
  RISC-V: lib: minor asm cleanup
  RISC-V: Update Kconfig to better handle CMDLINE
  riscv: remove unused variable in ftrace
  RISC-V: add of_node_put()
  RISC-V: Fix of_node_* refcount
  riscv, atomic: Add #define's for the atomic_{cmp,}xchg_*() variants
  RISC-V: Remove EARLY_PRINTK support
  RISC-V: defconfig: Enable RISC-V SBI earlycon support

arch/riscv/Kconfig

@@ -24,6 +24,7 @@ config RISCV
 	select GENERIC_CPU_DEVICES
 	select GENERIC_IRQ_SHOW
 	select GENERIC_PCI_IOMAP
+	select GENERIC_SCHED_CLOCK
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
 	select GENERIC_SMP_IDLE_THREAD
@@ -227,39 +228,48 @@ endmenu
 
 menu "Boot options"
 
-config CMDLINE_BOOL
-	bool "Built-in kernel command line"
-	help
-	  For most platforms, it is firmware or second stage bootloader
-	  that by default specifies the kernel command line options.
-	  However, it might be necessary or advantageous to either override
-	  the default kernel command line or add a few extra options to it.
-	  For such cases, this option allows hardcoding command line options
-	  directly into the kernel.
-
-	  For that, choose 'Y' here and fill in the extra boot parameters
-	  in CONFIG_CMDLINE.
-
-	  The built-in options will be concatenated to the default command
-	  line if CMDLINE_FORCE is set to 'N'. Otherwise, the default
-	  command line will be ignored and replaced by the built-in string.
-
 config CMDLINE
-	string "Built-in kernel command string"
-	depends on CMDLINE_BOOL
-	default ""
+	string "Built-in kernel command line"
 	help
-	  Supply command-line options at build time by entering them here.
+	  For most platforms, the arguments for the kernel's command line
+	  are provided at run-time, during boot. However, there are cases
+	  where either no arguments are being provided or the provided
+	  arguments are insufficient or even invalid.
+
+	  When that occurs, it is possible to define a built-in command
+	  line here and choose how the kernel should use it later on.
+
+choice
+	prompt "Built-in command line usage" if CMDLINE != ""
+	default CMDLINE_FALLBACK
+	help
+	  Choose how the kernel will handle the provided built-in command
+	  line.
+
+config CMDLINE_FALLBACK
+	bool "Use bootloader kernel arguments if available"
+	help
+	  Use the built-in command line as fallback in case we get nothing
+	  during boot. This is the default behaviour.
+
+config CMDLINE_EXTEND
+	bool "Extend bootloader kernel arguments"
+	help
+	  The command-line arguments provided during boot will be
+	  appended to the built-in command line. This is useful in
+	  cases where the provided arguments are insufficient and
+	  you don't want to or cannot modify them.
+
 
 config CMDLINE_FORCE
-	bool "Built-in command line overrides bootloader arguments"
-	depends on CMDLINE_BOOL
+	bool "Always use the default kernel command string"
 	help
-	  Set this option to 'Y' to have the kernel ignore the bootloader
-	  or firmware command line.  Instead, the built-in command line
-	  will be used exclusively.
+	  Always use the built-in command line, even if we get one during
+	  boot. This is useful in case you need to override the provided
+	  command line on systems where you don't have or want control
+	  over it.
 
-	  If you don't know what to do here, say N.
+endchoice
 
 endmenu
 

arch/riscv/Kconfig.debug

@@ -1,2 +0,0 @@
-config EARLY_PRINTK
-	def_bool y

arch/riscv/configs/defconfig

@@ -46,6 +46,7 @@ CONFIG_INPUT_MOUSEDEV=y
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_OF_PLATFORM=y
+CONFIG_SERIAL_EARLYCON_RISCV_SBI=y
 CONFIG_HVC_RISCV_SBI=y
 # CONFIG_PTP_1588_CLOCK is not set
 CONFIG_DRM=y

arch/riscv/include/asm/atomic.h

@@ -303,6 +303,15 @@ c_t atomic##prefix##_cmpxchg(atomic##prefix##_t *v, c_t o, c_t n)	\
 
 ATOMIC_OPS()
 
+#define atomic_xchg_relaxed atomic_xchg_relaxed
+#define atomic_xchg_acquire atomic_xchg_acquire
+#define atomic_xchg_release atomic_xchg_release
+#define atomic_xchg atomic_xchg
+#define atomic_cmpxchg_relaxed atomic_cmpxchg_relaxed
+#define atomic_cmpxchg_acquire atomic_cmpxchg_acquire
+#define atomic_cmpxchg_release atomic_cmpxchg_release
+#define atomic_cmpxchg atomic_cmpxchg
+
 #undef ATOMIC_OPS
 #undef ATOMIC_OP
 

arch/riscv/kernel/cacheinfo.c

@@ -28,6 +28,7 @@ static int __init_cache_level(unsigned int cpu)
 {
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
 	struct device_node *np = of_cpu_device_node_get(cpu);
+	struct device_node *prev = NULL;
 	int levels = 0, leaves = 0, level;
 
 	if (of_property_read_bool(np, "cache-size"))
@@ -39,7 +40,10 @@ static int __init_cache_level(unsigned int cpu)
 	if (leaves > 0)
 		levels = 1;
 
+	prev = np;
 	while ((np = of_find_next_cache_node(np))) {
+		of_node_put(prev);
+		prev = np;
 		if (!of_device_is_compatible(np, "cache"))
 			break;
 		if (of_property_read_u32(np, "cache-level", &level))
@@ -55,8 +59,10 @@ static int __init_cache_level(unsigned int cpu)
 		levels = level;
 	}
 
+	of_node_put(np);
 	this_cpu_ci->num_levels = levels;
 	this_cpu_ci->num_leaves = leaves;
+
 	return 0;
 }
 
@@ -65,6 +71,7 @@ static int __populate_cache_leaves(unsigned int cpu)
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
 	struct cacheinfo *this_leaf = this_cpu_ci->info_list;
 	struct device_node *np = of_cpu_device_node_get(cpu);
+	struct device_node *prev = NULL;
 	int levels = 1, level = 1;
 
 	if (of_property_read_bool(np, "cache-size"))
@@ -74,7 +81,10 @@ static int __populate_cache_leaves(unsigned int cpu)
 	if (of_property_read_bool(np, "d-cache-size"))
 		ci_leaf_init(this_leaf++, np, CACHE_TYPE_DATA, level);
 
+	prev = np;
 	while ((np = of_find_next_cache_node(np))) {
+		of_node_put(prev);
+		prev = np;
 		if (!of_device_is_compatible(np, "cache"))
 			break;
 		if (of_property_read_u32(np, "cache-level", &level))
@@ -89,6 +99,7 @@ static int __populate_cache_leaves(unsigned int cpu)
 			ci_leaf_init(this_leaf++, np, CACHE_TYPE_DATA, level);
 		levels = level;
 	}
+	of_node_put(np);
 
 	return 0;
 }

arch/riscv/kernel/cpu.c

@@ -158,6 +158,7 @@ static int c_show(struct seq_file *m, void *v)
 	    && strcmp(compat, "riscv"))
 		seq_printf(m, "uarch\t\t: %s\n", compat);
 	seq_puts(m, "\n");
+	of_node_put(node);
 
 	return 0;
 }

arch/riscv/kernel/cpufeature.c

@@ -56,8 +56,10 @@ void riscv_fill_hwcap(void)
 
 	if (of_property_read_string(node, "riscv,isa", &isa)) {
 		pr_warning("Unable to find \"riscv,isa\" devicetree entry");
+		of_node_put(node);
 		return;
 	}
+	of_node_put(node);
 
 	for (i = 0; i < strlen(isa); ++i)
 		elf_hwcap |= isa2hwcap[(unsigned char)(isa[i])];

arch/riscv/kernel/ftrace.c

@@ -132,7 +132,6 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 {
 	unsigned long return_hooker = (unsigned long)&return_to_handler;
 	unsigned long old;
-	int err;
 
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		return;

arch/riscv/kernel/perf_event.c

@@ -476,6 +476,7 @@ int __init init_hw_perf_events(void)
 
 		if (of_id)
 			riscv_pmu = of_id->data;
+		of_node_put(node);
 	}
 
 	perf_pmu_register(riscv_pmu->pmu, "cpu", PERF_TYPE_RAW);

arch/riscv/kernel/setup.c

@@ -35,31 +35,9 @@
 #include <asm/sections.h>
 #include <asm/pgtable.h>
 #include <asm/smp.h>
-#include <asm/sbi.h>
 #include <asm/tlbflush.h>
 #include <asm/thread_info.h>
 
-#ifdef CONFIG_EARLY_PRINTK
-static void sbi_console_write(struct console *co, const char *buf,
-			      unsigned int n)
-{
-	int i;
-
-	for (i = 0; i < n; ++i) {
-		if (buf[i] == '\n')
-			sbi_console_putchar('\r');
-		sbi_console_putchar(buf[i]);
-	}
-}
-
-struct console riscv_sbi_early_console_dev __initdata = {
-	.name	= "early",
-	.write	= sbi_console_write,
-	.flags	= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
-	.index	= -1
-};
-#endif
-
 #ifdef CONFIG_DUMMY_CONSOLE
 struct screen_info screen_info = {
 	.orig_video_lines	= 30,
@@ -219,12 +197,6 @@ static void __init setup_bootmem(void)
 
 void __init setup_arch(char **cmdline_p)
 {
-#if defined(CONFIG_EARLY_PRINTK)
-       if (likely(early_console == NULL)) {
-               early_console = &riscv_sbi_early_console_dev;
-               register_console(early_console);
-       }
-#endif
 	*cmdline_p = boot_command_line;
 
 	parse_early_param();

arch/riscv/kernel/smpboot.c

@@ -57,12 +57,15 @@ void __init setup_smp(void)
 
 	while ((dn = of_find_node_by_type(dn, "cpu"))) {
 		hart = riscv_of_processor_hartid(dn);
-		if (hart < 0)
+		if (hart < 0) {
+			of_node_put(dn);
 			continue;
+		}
 
 		if (hart == cpuid_to_hartid_map(0)) {
 			BUG_ON(found_boot_cpu);
 			found_boot_cpu = 1;
+			of_node_put(dn);
 			continue;
 		}
 
@@ -70,6 +73,7 @@ void __init setup_smp(void)
 		set_cpu_possible(cpuid, true);
 		set_cpu_present(cpuid, true);
 		cpuid++;
+		of_node_put(dn);
 	}
 
 	BUG_ON(!found_boot_cpu);

arch/riscv/kernel/time.c

@@ -26,6 +26,7 @@ void __init time_init(void)
 	cpu = of_find_node_by_path("/cpus");
 	if (!cpu || of_property_read_u32(cpu, "timebase-frequency", &prop))
 		panic(KERN_WARNING "RISC-V system with no 'timebase-frequency' in DTS\n");
+	of_node_put(cpu);
 	riscv_timebase = prop;
 
 	lpj_fine = riscv_timebase / HZ;

arch/riscv/lib/tishift.S

@@ -10,33 +10,36 @@
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *   GNU General Public License for more details.
  */
-  .globl __lshrti3
-__lshrti3:
-  beqz  a2, .L1
-  li    a5,64
-  sub   a5,a5,a2
-  addi  sp,sp,-16
-  sext.w a4,a5
-  blez  a5, .L2
-  sext.w a2,a2
-  sll   a4,a1,a4
-  srl   a0,a0,a2
-  srl   a1,a1,a2
-  or    a0,a0,a4
-  sd    a1,8(sp)
-  sd    a0,0(sp)
-  ld    a0,0(sp)
-  ld    a1,8(sp)
-  addi  sp,sp,16
-  ret
+
+#include <linux/linkage.h>
+
+ENTRY(__lshrti3)
+	beqz	a2, .L1
+	li	a5,64
+	sub	a5,a5,a2
+	addi	sp,sp,-16
+	sext.w	a4,a5
+	blez	a5, .L2
+	sext.w	a2,a2
+	sll	a4,a1,a4
+	srl	a0,a0,a2
+	srl	a1,a1,a2
+	or	a0,a0,a4
+	sd	a1,8(sp)
+	sd	a0,0(sp)
+	ld	a0,0(sp)
+	ld	a1,8(sp)
+	addi	sp,sp,16
+	ret
 .L1:
-  ret
+	ret
 .L2:
-  negw  a4,a4
-  srl   a1,a1,a4
-  sd    a1,0(sp)
-  sd    zero,8(sp)
-  ld    a0,0(sp)
-  ld    a1,8(sp)
-  addi  sp,sp,16
-  ret
+	negw	a4,a4
+	srl	a1,a1,a4
+	sd	a1,0(sp)
+	sd	zero,8(sp)
+	ld	a0,0(sp)
+	ld	a1,8(sp)
+	addi	sp,sp,16
+	ret
+ENDPROC(__lshrti3)

arch/riscv/lib/udivdi3.S

@@ -11,28 +11,30 @@
  *   GNU General Public License for more details.
  */
 
-  .globl __udivdi3
-__udivdi3:
-  mv    a2, a1
-  mv    a1, a0
-  li    a0, -1
-  beqz  a2, .L5
-  li    a3, 1
-  bgeu  a2, a1, .L2
+#include <linux/linkage.h>
+
+ENTRY(__udivdi3)
+	mv	a2, a1
+	mv	a1, a0
+	li	a0, -1
+	beqz	a2, .L5
+	li	a3, 1
+	bgeu	a2, a1, .L2
 .L1:
-  blez  a2, .L2
-  slli  a2, a2, 1
-  slli  a3, a3, 1
-  bgtu  a1, a2, .L1
+	blez	a2, .L2
+	slli	a2, a2, 1
+	slli	a3, a3, 1
+	bgtu	a1, a2, .L1
 .L2:
-  li    a0, 0
+	li	a0, 0
 .L3:
-  bltu  a1, a2, .L4
-  sub   a1, a1, a2
-  or    a0, a0, a3
+	bltu	a1, a2, .L4
+	sub	a1, a1, a2
+	or	a0, a0, a3
 .L4:
-  srli  a3, a3, 1
-  srli  a2, a2, 1
-  bnez  a3, .L3
+	srli	a3, a3, 1
+	srli	a2, a2, 1
+	bnez	a3, .L3
 .L5:
-  ret
+	ret
+ENDPROC(__udivdi3)