On 10/31/2014 01:58 PM, Kees Cook wrote:
> 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 <[email protected]>
> ---
> Since this displays run_size, this patch depends on Junjie Mao's patch
> "x86, kaslr: Prevent .bss from overlaping initrd"
>
This reminds me: I have a patch to add an early-boot IDT that can report
#GP and #PF in this code if CONFIG_X86_VERBOSE_BOOTUP is set. I can
dust it off if anyone thinks it'll be useful, even though I won't end up
needed it for the thing I wrote it for.
--Andy
> ---
> 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
>
>
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