From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-qt0-f180.google.com ([209.85.216.180]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1bz3Ou-0004Cr-Ja for kexec@lists.infradead.org; Tue, 25 Oct 2016 15:12:32 +0000 Received: by mail-qt0-f180.google.com with SMTP id g49so10861252qtc.6 for ; Tue, 25 Oct 2016 08:12:08 -0700 (PDT) Subject: Re: [PATCH Makedumpfile 2/4] x86_64: translate all VA to PA using page table values References: <0910DD04CBD6DE4193FCF86B9C00BE9701E7A30E@BPXM01GP.gisp.nec.co.jp> From: Pratyush Anand Message-ID: Date: Tue, 25 Oct 2016 20:42:02 +0530 MIME-Version: 1.0 In-Reply-To: <0910DD04CBD6DE4193FCF86B9C00BE9701E7A30E@BPXM01GP.gisp.nec.co.jp> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed"; DelSp="yes" Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Atsushi Kumagai , "bhe@redhat.com" Cc: "kexec@lists.infradead.org" , "dyoung@redhat.com" Hi Atsushi, Thanks for the review. On Tuesday 25 October 2016 02:50 PM, Atsushi Kumagai wrote: > Hello Pratysh, > >> Currently we translate some of the VA areas using linear mapping while some >> other(which can not be linearly mapped) using page table. >> >> However, we will have entry of a page in the page table irrespective of its >> virtual region. So, we can always look into page table for any VA to PA >> translation. This approach will solve lot of complexity in makedumpfile. It >> will in turn remove dependency over variables like VMALLOC_START, >> MODULES_VADDR etc whose definition keeps changing in newer kernel version. >> >> Moreover, I do not see any side effect of this approach in terms of >> execution timing. I tested with IBM x3950 X6 machine having 4136359 MB of >> memory. These are the results of makedumpfile execution time: >> >> Without this patch: >> =================== >> With -d 31: >> Trial 1: 237.59526248 S >> Trial 2: 235.236914962 S >> Trail 3: 237.678712045 S >> >> With -d 1: >> Trial 1: 2548.905296877 S >> Trial 2: 2549.759881756 S >> >> With this patch: >> =================== >> With -d 31: >> Trial 1: 232.713841516 S >> Trial 2: 228.45697177 S >> Trail 3: 232.942262441 S >> >> With -d 1: >> Trial 1: 2768.424565806 S >> Trial 2: 2749.622115455 S >> Trail 3: 2537.770359073 S > > Could you increase the number of trials ? OK, I can do that. Might take some time, as I will have to arrange that high memory machine again. > If the average time is close to the results of Trial 1 (2768s) and 2 (2749s), > the regression rate is 8% and it sounds neither large nor small. > If the average is a level of 2500s like Trial 3, it's ideal. > >> Signed-off-by: Pratyush Anand >> --- >> arch/x86_64.c | 42 ++++++++---------------------------------- >> makedumpfile.h | 4 ++-- >> 2 files changed, 10 insertions(+), 36 deletions(-) >> >> diff --git a/arch/x86_64.c b/arch/x86_64.c >> index a96fd8ae00a1..fe2764a8bec2 100644 >> --- a/arch/x86_64.c >> +++ b/arch/x86_64.c >> @@ -203,6 +203,12 @@ vtop4_x86_64(unsigned long vaddr) >> { >> unsigned long page_dir, pml4, pgd_paddr, pgd_pte, pmd_paddr, pmd_pte; >> unsigned long pte_paddr, pte; >> + unsigned long phys_base; >> + >> + if (SYMBOL(phys_base) != NOT_FOUND_SYMBOL) >> + phys_base = info->phys_base; >> + else >> + phys_base = 0; >> >> if (SYMBOL(init_level4_pgt) == NOT_FOUND_SYMBOL) { >> ERRMSG("Can't get the symbol of init_level4_pgt.\n"); >> @@ -212,9 +218,9 @@ vtop4_x86_64(unsigned long vaddr) >> /* >> * Get PGD. >> */ >> - page_dir = SYMBOL(init_level4_pgt); >> + page_dir = SYMBOL(init_level4_pgt) - __START_KERNEL_map + phys_base; > > I want to confirm that this VA to PA translation is always safe, > otherwise we should do the condition check which was done in > vaddr_to_paddr_x86_64(), isn't it ? > I think this should be safe, however x86 expert can comment better. Baoquan any comment here? ~Pratyush > > Thanks, > Atsushi Kumagai > >> page_dir += pml4_index(vaddr) * sizeof(unsigned long); >> - if (!readmem(VADDR, page_dir, &pml4, sizeof pml4)) { >> + if (!readmem(PADDR, page_dir, &pml4, sizeof pml4)) { >> ERRMSG("Can't get pml4 (page_dir:%lx).\n", page_dir); >> return NOT_PADDR; >> } >> @@ -285,38 +291,6 @@ vtop4_x86_64(unsigned long vaddr) >> return (pte & ENTRY_MASK) + PAGEOFFSET(vaddr); >> } >> >> -unsigned long long >> -vaddr_to_paddr_x86_64(unsigned long vaddr) >> -{ >> - unsigned long phys_base; >> - unsigned long long paddr; >> - >> - /* >> - * Check the relocatable kernel. >> - */ >> - if (SYMBOL(phys_base) != NOT_FOUND_SYMBOL) >> - phys_base = info->phys_base; >> - else >> - phys_base = 0; >> - >> - if (is_vmalloc_addr_x86_64(vaddr)) { >> - if ((paddr = vtop4_x86_64(vaddr)) == NOT_PADDR) { >> - ERRMSG("Can't convert a virtual address(%lx) to " \ >> - "physical address.\n", vaddr); >> - return NOT_PADDR; >> - } >> - } else if (vaddr >= __START_KERNEL_map) { >> - paddr = vaddr - __START_KERNEL_map + phys_base; >> - >> - } else { >> - if (is_xen_memory()) >> - paddr = vaddr - PAGE_OFFSET_XEN_DOM0; >> - else >> - paddr = vaddr - PAGE_OFFSET; >> - } >> - return paddr; >> -} >> - >> /* >> * for Xen extraction >> */ >> diff --git a/makedumpfile.h b/makedumpfile.h >> index a5955ff750e5..13559651feb6 100644 >> --- a/makedumpfile.h >> +++ b/makedumpfile.h >> @@ -863,12 +863,12 @@ int is_vmalloc_addr_x86_64(ulong vaddr); >> int get_phys_base_x86_64(void); >> int get_machdep_info_x86_64(void); >> int get_versiondep_info_x86_64(void); >> -unsigned long long vaddr_to_paddr_x86_64(unsigned long vaddr); >> +unsigned long long vtop4_x86_64(unsigned long vaddr); >> #define find_vmemmap() find_vmemmap_x86_64() >> #define get_phys_base() get_phys_base_x86_64() >> #define get_machdep_info() get_machdep_info_x86_64() >> #define get_versiondep_info() get_versiondep_info_x86_64() >> -#define vaddr_to_paddr(X) vaddr_to_paddr_x86_64(X) >> +#define vaddr_to_paddr(X) vtop4_x86_64(X) >> #define is_phys_addr(X) (!is_vmalloc_addr_x86_64(X)) >> #endif /* x86_64 */ >> >> -- >> 2.7.4 >> >> >> _______________________________________________ >> 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