Messages in this thread | | | Date | Tue, 01 Feb 2011 00:12:30 +0100 | From | matthieu castet <> | Subject | Re: [BUG] broken ebba638ae723d8a8fc2f7abce5ec18b688b791d7 |
| |
Kees Cook a écrit : > Hi, > > On Thu, Jan 27, 2011 at 06:24:14PM -0800, H. Peter Anvin wrote: >> On 01/27/2011 03:00 PM, Kees Cook wrote: >>> Yikes, good catch. >>> >>> arch/x86/kernel/trampoline_64.S uses: >>> movw $(trampoline_stack_end - r_base), %sp >>> >>> arch/x86/boot/compressed/head_64.S uses: >>> movl $boot_stack_end, %eax >>> addl %ebp, %eax >>> movl %eax, %esp >>> >>> what would be safe for arch/x86/kernel/head_32.S ? It uses "stack_start", >>> but later after paging set-up. Is the following sane to solve this? >>> >> To run it before paging is set up, you can't use stack, start; you >> have to use a pointer based on physical address. You have two >> problems with using stack_start: you're using a linear address to >> access stack_start, and stack_start itself contains a linear >> address. >> >> It's not entirely clear to me why we don't initialize %ss to >> __BOOT_DS with the other segment registers, but it would make most >> sense to me: >> >> diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S >> index fc293dc..c10f9ba 100644 >> --- a/arch/x86/kernel/head_32.S >> +++ b/arch/x86/kernel/head_32.S >> @@ -99,7 +99,12 @@ ENTRY(startup_32) >> movl %eax,%es >> movl %eax,%fs >> movl %eax,%gs >> + movl %eax,%ss >> 2: >> +/* >> + * Set up an initial stack >> + */ >> + movl $pa(init_thread_union+THREAD_SIZE), %esp >> >> /* >> * Clear BSS first so that there are no surprises... > > This doesn't appear to work for me. While I can boot fine, doing CPU > hotplugging hangs the system. :( > That's because of NX :)
The stack is marked NX, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |