From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pl0-x243.google.com ([2607:f8b0:400e:c01::243]) by bombadil.infradead.org with esmtps (Exim 4.89 #1 (Red Hat Linux)) id 1erdiQ-0003EH-Gu for kexec@lists.infradead.org; Fri, 02 Mar 2018 05:58:48 +0000 Received: by mail-pl0-x243.google.com with SMTP id 93-v6so5089673plc.9 for ; Thu, 01 Mar 2018 21:58:36 -0800 (PST) Date: Fri, 2 Mar 2018 14:58:48 +0900 From: AKASHI Takahiro Subject: Re: [PATCH 6/7] x86: kexec_file: clean up prepare_elf64_headers() Message-ID: <20180302055845.GR6019@linaro.org> References: <20180227044814.24808-1-takahiro.akashi@linaro.org> <20180227044814.24808-7-takahiro.akashi@linaro.org> <20180302053945.GD2952@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20180302053945.GD2952@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: linux-s390@vger.kernel.org, prudo@linux.vnet.ibm.com, bhe@redhat.com, mpe@ellerman.id.au, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, bauerman@linux.vnet.ibm.com, vgoyal@redhat.com On Fri, Mar 02, 2018 at 01:39:45PM +0800, Dave Young wrote: > On 02/27/18 at 01:48pm, AKASHI Takahiro wrote: > > removing bufp variable in prepare_elf64_headers() makes the code simpler > > and more understandable. > > > > Signed-off-by: AKASHI Takahiro > > Cc: Dave Young > > Cc: Vivek Goyal > > Cc: Baoquan He > > --- > > arch/x86/kernel/crash.c | 18 +++++++----------- > > 1 file changed, 7 insertions(+), 11 deletions(-) > > > > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > > index bfc37ad20d4a..a842fd847684 100644 > > --- a/arch/x86/kernel/crash.c > > +++ b/arch/x86/kernel/crash.c > > @@ -334,7 +334,7 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map, > > Elf64_Ehdr *ehdr; > > Elf64_Phdr *phdr; > > unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz; > > - unsigned char *buf, *bufp; > > + unsigned char *buf; > > unsigned int cpu, i; > > unsigned long long notes_addr; > > unsigned long mstart, mend; > > @@ -359,9 +359,8 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map, > > if (!buf) > > return -ENOMEM; > > > > - bufp = buf; > > - ehdr = (Elf64_Ehdr *)bufp; > > - bufp += sizeof(Elf64_Ehdr); > > + ehdr = (Elf64_Ehdr *)buf; > > + phdr = (Elf64_Phdr *)(ehdr + 1); > > phdr should start with ehdr + sizeof(Elf64_Ehdr); Well, it's a matter of rhetoric :) The values from both expressions are the same. Or do you mean my expression is confusing? -Takahiro AKASHI > > memcpy(ehdr->e_ident, ELFMAG, SELFMAG); > > ehdr->e_ident[EI_CLASS] = ELFCLASS64; > > ehdr->e_ident[EI_DATA] = ELFDATA2LSB; > > @@ -377,33 +376,30 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map, > > > > /* Prepare one phdr of type PT_NOTE for each present cpu */ > > for_each_present_cpu(cpu) { > > - phdr = (Elf64_Phdr *)bufp; > > - bufp += sizeof(Elf64_Phdr); > > phdr->p_type = PT_NOTE; > > notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu)); > > phdr->p_offset = phdr->p_paddr = notes_addr; > > phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t); > > (ehdr->e_phnum)++; > > + phdr++; > > } > > > > /* Prepare one PT_NOTE header for vmcoreinfo */ > > - phdr = (Elf64_Phdr *)bufp; > > - bufp += sizeof(Elf64_Phdr); > > phdr->p_type = PT_NOTE; > > phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note(); > > phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE; > > (ehdr->e_phnum)++; > > + phdr++; > > > > /* Prepare PT_LOAD type program header for kernel text region */ > > if (kernel_map) { > > - phdr = (Elf64_Phdr *)bufp; > > - bufp += sizeof(Elf64_Phdr); > > phdr->p_type = PT_LOAD; > > phdr->p_flags = PF_R|PF_W|PF_X; > > phdr->p_vaddr = (Elf64_Addr)_text; > > phdr->p_filesz = phdr->p_memsz = _end - _text; > > phdr->p_offset = phdr->p_paddr = __pa_symbol(_text); > > - (ehdr->e_phnum)++; > > + ehdr->e_phnum++; > > + phdr++; > > } > > > > /* Go through all the ranges in cmem->ranges[] and prepare phdr */ > > -- > > 2.16.2 > > > > Thanks > Dave _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec