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Message-ID: <20141031205819.GA13262@www.outflux.net>
Date: Fri, 31 Oct 2014 13:58:19 -0700
From: Kees Cook <keescook@...omium.org>
To: linux-kernel@...r.kernel.org
Cc: "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
Vivek Goyal <vgoyal@...hat.com>,
Josh Triplett <josh@...htriplett.org>,
Junjie Mao <eternal.n08@...il.com>,
Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH v2] x86, boot: add hex output for debugging
This is useful for reporting various addresses or other values while
debugging early boot. 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@...omium.org>
---
Since this displays run_size, this patch depends on Junjie Mao's patch
"x86, kaslr: Prevent .bss from overlaping initrd"
---
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 30dd59a9f0b4..2aefc8a63655 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");
@@ -382,6 +399,13 @@ 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 24e3e569a13c..70472ae98a73 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
--
1.9.1
--
Kees Cook
Chrome OS Security
--
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