Messages in this thread | | | Date | Tue, 20 Dec 2011 17:33:49 -0800 | From | Maxim Uvarov <> | Subject | Re: [PATCH] hpwd watchdog mark page executable |
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On 12/20/2011 04:50 PM, Andrew Morton wrote: > On Mon, 5 Dec 2011 16:25:39 -0800 > Maxim Uvarov<maxim.uvarov@oracle.com> wrote: > >> Mark hpwdt watchdog pages executable to prevent failing: >> BUG: unable to handle kernel paging request at c00f0000 >> IP: [<c00f0000>] 0xc00effff >> *pdpt = 0000000000b7c001 *pde = 0000000000cf5067 *pte = 80000000000f0163 >> Oops: 0011 [#1] SMP >> >> ... >> >> --- a/drivers/watchdog/hpwdt.c >> +++ b/drivers/watchdog/hpwdt.c >> @@ -335,6 +335,8 @@ static int __devinit detect_cru_service(void) >> if (p == NULL) >> return -ENOMEM; >> >> + set_memory_x((unsigned long)p& PAGE_MASK, ROM_SIZE>> PAGE_SHIFT); >> + >> for (q = p; q< p + ROM_SIZE; q += 16) { >> rc = bios32_present(q); >> if (!rc) > > Odd. Either nobody else is using this driver, or there's something > special about your setup. Are you able to explain this? >
Code drivers/watchdog/hpwdt.c is ifdefed on 2 branches for 32 and 64 bit accordingly. For 64 bit address for watchdog handler is used from smbios, for 32 bit - from ioremap(0x000F0000, ). Accordingly 64 kernel unsets _PAGE_NX flag to pages. I.e. calls set_memory_x(). But 32 bit did not do so. It worked on 2.6.32 and since 3.0 looks like additional page protection code was added. I can't find the right commit which changed it right now.
> Also, do you believe that this fix should be backported into earlier > stable kernels and if so, why? > Andrew, I found this problem in 3.0 than checked that it exist in linux-next when it was 3.1+. Because it's panic on module loading, yes this is critical bug and it's needs to be back-ported. (Actually this driver was not changed so simple cherry-pick one line patch will work.).
Maxim. > Thanks.
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