[tip:x86/boot] x86/boot: Add hex output for debugging

[tip-bot for Kees Cook]

Commit-ID:  79063a7c0239419d5f6bee63228f66256fdc0fc4
Gitweb:     http://git.kernel.org/tip/79063a7c0239419d5f6bee63228f66256fdc0fc4
Author:     Kees Cook <keescook@xxxxxxxxxxxx>
AuthorDate: Mon, 6 Jul 2015 16:06:20 -0700
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 7 Jul 2015 08:59:05 +0200

x86/boot: Add hex output for debugging

This is useful for reporting various addresses or other values
while debugging early boot, for example, the recent kernel image
size vs kernel run size. For example, when
CONFIG_X86_VERBOSE_BOOTUP is set, this is now visible at boot
time:

	early console in setup code
	early console in decompress_kernel
	input_data: 0x0000000001e1526e
	input_len: 0x0000000000732236
	output: 0x0000000001000000
	output_len: 0x0000000001535640
	run_size: 0x00000000021fb000
	KASLR using RDTSC...

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Jan Beulich <JBeulich@xxxxxxxx>
Cc: Jiri Kosina <jkosina@xxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Junjie Mao <eternal.n08@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20150706230620.GA17501@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/boot/compressed/misc.c | 24 ++++++++++++++++++++++++
 arch/x86/boot/compressed/misc.h | 11 +++++++++++
 2 files changed, 35 insertions(+)

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index a107b93..f637979 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -220,6 +220,23 @@ void __putstr(const char *s)
 	outb(0xff & (pos >> 1), vidport+1);
 }
 
+void __puthex(unsigned long value)
+{
+	char alpha[2] = "0";
+	int bits;
+
+	for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
+		unsigned long digit = (value >> bits) & 0xf;
+
+		if (digit < 0xA)
+			alpha[0] = '0' + digit;
+		else
+			alpha[0] = 'a' + (digit - 0xA);
+
+		__putstr(alpha);
+	}
+}
+
 static void error(char *x)
 {
 	error_putstr("\n\n");
@@ -399,6 +416,13 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
 	free_mem_ptr     = heap;	/* Heap */
 	free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
 
+	/* Report initial kernel position details. */
+	debug_putaddr(input_data);
+	debug_putaddr(input_len);
+	debug_putaddr(output);
+	debug_putaddr(output_len);
+	debug_putaddr(run_size);
+
 	/*
 	 * The memory hole needed for the kernel is the larger of either
 	 * the entire decompressed kernel plus relocation table, or the
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 805d25c..3783dc3 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -34,16 +34,27 @@ extern memptr free_mem_ptr;
 extern memptr free_mem_end_ptr;
 extern struct boot_params *real_mode;		/* Pointer to real-mode data */
 void __putstr(const char *s);
+void __puthex(unsigned long value);
 #define error_putstr(__x)  __putstr(__x)
+#define error_puthex(__x)  __puthex(__x)
 
 #ifdef CONFIG_X86_VERBOSE_BOOTUP
 
 #define debug_putstr(__x)  __putstr(__x)
+#define debug_puthex(__x)  __puthex(__x)
+#define debug_putaddr(__x) { \
+		debug_putstr(#__x ": 0x"); \
+		debug_puthex((unsigned long)(__x)); \
+		debug_putstr("\n"); \
+	}
 
 #else
 
 static inline void debug_putstr(const char *s)
 { }
+static inline void debug_puthex(const char *s)
+{ }
+#define debug_putaddr(x) /* */
 
 #endif
 
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