ARC: [cmdline] uboot cmdline handling rework

* Moved cmdline copy from asm to "C" - allows for more robust checking
  of pointer validity etc.

* Remove the Kconfig option to do so, base it on a runtime value passed
  by u-boot

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 9063ae6..c1f76f7 100644 (file)
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -409,17 +409,6 @@ config ARC_DBG_TLB_MISS_COUNT
          Counts number of I and D TLB Misses and exports them via Debugfs
          The counters can be cleared via Debugfs as well
 
-config CMDLINE_UBOOT
-       bool "Support U-boot kernel command line passing"
-       default n
-       help
-         If you are using U-boot (www.denx.de) and wish to pass the kernel
-         command line from the U-boot environment to the Linux kernel then
-         switch this option on.
-         ARC U-boot will setup the cmdline in RAM/flash and set r2 to point
-         to it. kernel startup code will append this to DeviceTree
-         /bootargs provided cmdline args.
-
 config ARC_BUILTIN_DTB_NAME
        string "Built in DTB"
        help

diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S
index 2c878e9..9919972 100644 (file)
--- a/arch/arc/kernel/head.S
+++ b/arch/arc/kernel/head.S
@@ -49,25 +49,13 @@ stext:
        st.ab   0, [r5,4]
        brlt    r5, r6, 1b
 
-#ifdef CONFIG_CMDLINE_UBOOT
-       ; support for bootloader provided cmdline
-       ;    If cmdline passed by u-boot, then
-       ;    r0 = 1  (because ATAGS parsing, now retired, used to use 0)
-       ;    r1 = magic number (board identity)
-       ;    r2 = addr of cmdline string (somewhere in memory/flash)
-
-       brne    r0, 1, .Lother_bootup_chores    ; u-boot didn't pass cmdline
-       breq    r2, 0, .Lother_bootup_chores    ; or cmdline is NULL
-
-       mov     r5, @command_line
-1:
-       ldb.ab  r6, [r2, 1]
-       breq    r6, 0, .Lother_bootup_chores
-       b.d     1b
-       stb.ab  r6, [r5, 1]
-#endif
-
-.Lother_bootup_chores:
+       ; Uboot - kernel ABI
+       ;    r0 = [0] No uboot interaction, [1] cmdline in r2, [2] DTB in r2
+       ;    r1 = magic number (board identity, unused as of now
+       ;    r2 = pointer to uboot provided cmdline or external DTB in mem
+       ; These are handled later in setup_arch()
+       st      r0, [@uboot_tag]
+       st      r2, [@uboot_arg]
 
        ; Identify if running on ISS vs Silicon
        ;       IDENTITY Reg [ 3  2  1  0 ]

diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 643eae4..ffb60b4 100644 (file)
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -29,7 +29,10 @@
 
 int running_on_hw = 1; /* vs. on ISS */
 
-char __initdata command_line[COMMAND_LINE_SIZE];
+/* Part of U-boot ABI: see head.S */
+int __initdata uboot_tag;
+char __initdata *uboot_arg;
+
 const struct machine_desc *machine_desc;
 
 struct task_struct *_current_task[NR_CPUS];    /* For stack switching */
@@ -311,19 +314,31 @@ void setup_processor(void)
        arc_chk_fpu();
 }
 
+static inline int is_kernel(unsigned long addr)
+{
+       if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
+               return 1;
+       return 0;
+}
+
 void __init setup_arch(char **cmdline_p)
 {
-       /* This also populates @boot_command_line from /bootargs */
-       machine_desc = setup_machine_fdt(__dtb_start);
-       if (!machine_desc)
-               panic("Embedded DT invalid\n");
-
-       /* Append any u-boot provided cmdline */
-#ifdef CONFIG_CMDLINE_UBOOT
-       /* Add a whitespace seperator between the 2 cmdlines */
-       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
-       strlcat(boot_command_line, command_line, COMMAND_LINE_SIZE);
-#endif
+               machine_desc = setup_machine_fdt(__dtb_start);
+               if (!machine_desc)
+                       panic("Embedded DT invalid\n");
+
+               /*
+                * Append uboot cmdline to embedded DT cmdline.
+                * setup_machine_fdt() would have populated @boot_command_line
+                */
+               if (uboot_tag == 1) {
+                       BUG_ON(is_kernel(unsigned long)uboot_arg);
+
+                       /* Ensure a whitespace between the 2 cmdlines */
+                       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
+                       strlcat(boot_command_line, uboot_arg,
+                               COMMAND_LINE_SIZE);
+               }
 
        /* Save unparsed command line copy for /proc/cmdline */
        *cmdline_p = boot_command_line;