From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by merlin.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1cjNBA-0007gq-Kz for kexec@lists.infradead.org; Thu, 02 Mar 2017 09:37:45 +0000 Date: Thu, 2 Mar 2017 17:36:50 +0800 From: Baoquan He Subject: Re: [PATCH] Only search page_offset_base when KASLR mm code is compiled in Message-ID: <20170302093650.GD18391@x1> References: <1487932732-24539-1-git-send-email-bhe@redhat.com> <20170228060625.GA4872@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20170228060625.GA4872@dhcp-128-65.nay.redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Dave Young Cc: horms@verge.net.au, kexec@lists.infradead.org, piliu@redhat.com On 02/28/17 at 02:06pm, Dave Young wrote: > 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 > > --- > > 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. Could be it only works when make header and install. Otherwise it can't be seen by user space. I built a rhel kernel package and test passed. Anyway, since it doesn't work in all cases, I have made another way to fix it, just take out the error message and put it where get_kernel_sym is called. > > 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 > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec