[PATCH V2] arm64: Fix early pointer print plus improve comment

["Guilherme G. Piccoli" <gpiccoli@igalia.com>]

When facing a really early issue on DT parsing we have currently
a message that shows both the physical and virtual address of the
FDT. The printk pointer modifier there is not right for the virtual
address, due to the hashed address stuff, so hereby we fix that.

Also, we tried to improve a bit the commenting on that function, given
that if kernel fails there, it just hangs forever in a cpu_relax() loop.
The reason we cannot BUG/panic is that is too early to do so; thanks to
Mark Brown for pointing that on IRC.

Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
---

V2: Fixing the right pointer here - it's the virtual one, not the
physical! Thanks a bunch Robin Murphy for the review.

 arch/arm64/kernel/setup.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index be5f85b0a24d..172463ea6877 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -189,11 +189,15 @@ static void __init setup_machine_fdt(phys_addr_t dt_phys)
 
 	if (!dt_virt || !early_init_dt_scan(dt_virt)) {
 		pr_crit("\n"
-			"Error: invalid device tree blob at physical address %pa (virtual address 0x%p)\n"
+			"Error: invalid device tree blob at physical address %pa (virtual address 0x%px)\n"
 			"The dtb must be 8-byte aligned and must not exceed 2 MB in size\n"
 			"\nPlease check your bootloader.",
 			&dt_phys, dt_virt);
 
+		/* Note that in this _really_ early stage we cannot even BUG()
+		 * or oops, so the least terrible thing to do is cpu_relax(),
+		 * or else we could end-up printing non-initialized data, etc.
+		 */
 		while (true)
 			cpu_relax();
 	}
-- 
2.34.1


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