From: Dave Young <dyoung@redhat.com>
To: Baoquan He <bhe@redhat.com>
Cc: horms@verge.net.au, kexec@lists.infradead.org, piliu@redhat.com
Subject: Re: [PATCH] Only search page_offset_base when KASLR mm code is compiled in
Date: Tue, 28 Feb 2017 14:06:25 +0800 [thread overview]
Message-ID: <20170228060625.GA4872@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <1487932732-24539-1-git-send-email-bhe@redhat.com>
On 02/24/17 at 06:38pm, Baoquan He wrote:
> Otherwise it will print false positve message as below. So add
> a check when do the search.
>
> "Cannot get kernel page_offset_base symbol address"
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> kexec/arch/i386/crashdump-x86.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
> index 88aeee3..b2c1be5 100644
> --- a/kexec/arch/i386/crashdump-x86.c
> +++ b/kexec/arch/i386/crashdump-x86.c
> @@ -150,8 +150,6 @@ static int get_kernel_vaddr_and_size(struct kexec_info *UNUSED(info),
> off_t size;
> uint32_t elf_flags = 0;
> uint64_t stext_sym;
> - const unsigned long long pud_mask = ~((1 << 30) - 1);
> - unsigned long long vaddr, lowest_vaddr = 0;
>
> if (elf_info->machine != EM_X86_64)
> return 0;
> @@ -181,8 +179,11 @@ static int get_kernel_vaddr_and_size(struct kexec_info *UNUSED(info),
>
> end_phdr = &ehdr.e_phdr[ehdr.e_phnum];
>
> +#ifdef CONFIG_RANDOMIZE_MEMORY
It does not work in userspace code.
Maybe mute the error message or move it to kexec --debug is more
reasonable..
> /* Search for the real PAGE_OFFSET when KASLR memory randomization
> * is enabled */
> + const unsigned long long pud_mask = ~((1 << 30) - 1);
> + unsigned long long vaddr, lowest_vaddr = 0;
> if (get_kernel_sym("page_offset_base") != 0) {
> for(phdr = ehdr.e_phdr; phdr != end_phdr; phdr++) {
> if (phdr->p_type == PT_LOAD) {
> @@ -194,6 +195,7 @@ static int get_kernel_vaddr_and_size(struct kexec_info *UNUSED(info),
> if (lowest_vaddr != 0)
> elf_info->page_offset = lowest_vaddr;
> }
> +#endif
>
> /* Traverse through the Elf headers and find the region where
> * _stext symbol is located in. That's where kernel is mapped */
> --
> 2.5.5
>
>
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
Thanks
Dave
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next prev parent reply other threads:[~2017-02-28 6:07 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-24 10:38 [PATCH] Only search page_offset_base when KASLR mm code is compiled in Baoquan He
2017-02-28 6:06 ` Dave Young [this message]
2017-03-02 9:36 ` Baoquan He
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