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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3 03/10] xen: add elfnote.h to avoid using numbers instead of constants
On Wed, Feb 17, 2016 at 06:19:30PM +0100, Juergen Gross wrote:
> Various features and parameters of a pv-kernel are specified via
> elf notes in the kernel image. Those notes are part of the interface
> between the Xen hypervisor and the kernel.
>
> Instead of using num,bers in the code when interpreting the elf notes
> make use of the header supplied by Xen for that purpose.
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Yummy! Just one nitpick.
Reviewed-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
> ---
> grub-core/loader/i386/xen_fileXX.c | 19 +--
> include/xen/elfnote.h | 281
> +++++++++++++++++++++++++++++++++++++
> 2 files changed, 291 insertions(+), 9 deletions(-)
> create mode 100644 include/xen/elfnote.h
>
> diff --git a/grub-core/loader/i386/xen_fileXX.c
> b/grub-core/loader/i386/xen_fileXX.c
> index 5475819..1f7f71d 100644
> --- a/grub-core/loader/i386/xen_fileXX.c
> +++ b/grub-core/loader/i386/xen_fileXX.c
> @@ -18,6 +18,7 @@
>
> #include <grub/xen_file.h>
> #include <grub/misc.h>
> +#include <xen/elfnote.h>
>
> static grub_err_t
> parse_xen_guest (grub_elf_t elf, struct grub_xen_file_info *xi,
> @@ -201,35 +202,35 @@ parse_note (grub_elf_t elf, struct grub_xen_file_info
> *xi,
> xi->has_note = 1;
> switch (nh->n_type)
> {
> - case 1:
> + case XEN_ELFNOTE_ENTRY:
> xi->entry_point = grub_le_to_cpu_addr (*(Elf_Addr *) desc);
> break;
> - case 2:
> + case XEN_ELFNOTE_HYPERCALL_PAGE:
> xi->hypercall_page = grub_le_to_cpu_addr (*(Elf_Addr *) desc);
> xi->has_hypercall_page = 1;
> break;
> - case 3:
> + case XEN_ELFNOTE_VIRT_BASE:
> xi->virt_base = grub_le_to_cpu_addr (*(Elf_Addr *) desc);
> break;
> - case 4:
> + case XEN_ELFNOTE_PADDR_OFFSET:
> xi->paddr_offset = grub_le_to_cpu_addr (*(Elf_Addr *) desc);
> break;
> - case 5:
> + case XEN_ELFNOTE_XEN_VERSION:
> grub_dprintf ("xen", "xenversion = `%s'\n", (char *) desc);
> break;
> - case 6:
> + case XEN_ELFNOTE_GUEST_OS:
> grub_dprintf ("xen", "name = `%s'\n", (char *) desc);
> break;
> - case 7:
> + case XEN_ELFNOTE_GUEST_VERSION:
> grub_dprintf ("xen", "version = `%s'\n", (char *) desc);
> break;
> - case 8:
> + case XEN_ELFNOTE_LOADER:
> if (descsz < 7
> || grub_memcmp (desc, "generic", descsz == 7 ? 7 : 8) != 0)
> return grub_error (GRUB_ERR_BAD_OS, "invalid loader");
> break;
> /* PAE */
> - case 9:
> + case XEN_ELFNOTE_PAE_MODE:
> grub_dprintf ("xen", "pae = `%s', %d, %d\n", (char *) desc,
> xi->arch, descsz);
> if (xi->arch != GRUB_XEN_FILE_I386
> diff --git a/include/xen/elfnote.h b/include/xen/elfnote.h
> new file mode 100644
> index 0000000..353985f
> --- /dev/null
> +++ b/include/xen/elfnote.h
> @@ -0,0 +1,281 @@
> +/******************************************************************************
> + * elfnote.h
> + *
> + * Definitions used for the Xen ELF notes.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> copy
> + * of this software and associated documentation files (the "Software"), to
> + * deal in the Software without restriction, including without limitation the
> + * rights to use, copy, modify, merge, publish, distribute, sublicense,
> and/or
> + * sell copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> + * DEALINGS IN THE SOFTWARE.
> + *
> + * Copyright (c) 2006, Ian Campbell, XenSource Ltd.
> + */
> +
> +#ifndef __XEN_PUBLIC_ELFNOTE_H__
> +#define __XEN_PUBLIC_ELFNOTE_H__
> +
> +/*
> + * `incontents 200 elfnotes ELF notes
> + *
> + * The notes should live in a PT_NOTE segment and have "Xen" in the
> + * name field.
> + *
> + * Numeric types are either 4 or 8 bytes depending on the content of
> + * the desc field.
> + *
> + * LEGACY indicated the fields in the legacy __xen_guest string which
> + * this a note type replaces.
> + *
> + * String values (for non-legacy) are NULL terminated ASCII, also known
> + * as ASCIZ type.
> + */
> +
> +/*
> + * NAME=VALUE pair (string).
> + */
> +#define XEN_ELFNOTE_INFO 0
> +
> +/*
> + * The virtual address of the entry point (numeric).
> + *
> + * LEGACY: VIRT_ENTRY
> + */
> +#define XEN_ELFNOTE_ENTRY 1
> +
> +/* The virtual address of the hypercall transfer page (numeric).
> + *
> + * LEGACY: HYPERCALL_PAGE. (n.b. legacy value is a physical page
> + * number not a virtual address)
> + */
> +#define XEN_ELFNOTE_HYPERCALL_PAGE 2
> +
> +/* The virtual address where the kernel image should be mapped (numeric).
> + *
> + * Defaults to 0.
> + *
> + * LEGACY: VIRT_BASE
> + */
> +#define XEN_ELFNOTE_VIRT_BASE 3
> +
> +/*
> + * The offset of the ELF paddr field from the actual required
> + * pseudo-physical address (numeric).
> + *
> + * This is used to maintain backwards compatibility with older kernels
> + * which wrote __PAGE_OFFSET into that field. This field defaults to 0
> + * if not present.
> + *
> + * LEGACY: ELF_PADDR_OFFSET. (n.b. legacy default is VIRT_BASE)
> + */
> +#define XEN_ELFNOTE_PADDR_OFFSET 4
> +
> +/*
> + * The version of Xen that we work with (string).
> + *
> + * LEGACY: XEN_VER
> + */
> +#define XEN_ELFNOTE_XEN_VERSION 5
> +
> +/*
> + * The name of the guest operating system (string).
> + *
> + * LEGACY: GUEST_OS
> + */
> +#define XEN_ELFNOTE_GUEST_OS 6
> +
> +/*
> + * The version of the guest operating system (string).
> + *
> + * LEGACY: GUEST_VER
> + */
> +#define XEN_ELFNOTE_GUEST_VERSION 7
> +
> +/*
> + * The loader type (string).
> + *
> + * LEGACY: LOADER
> + */
> +#define XEN_ELFNOTE_LOADER 8
> +
> +/*
> + * The kernel supports PAE (x86/32 only, string = "yes", "no" or
> + * "bimodal").
> + *
> + * For compatibility with Xen 3.0.3 and earlier the "bimodal" setting
> + * may be given as "yes,bimodal" which will cause older Xen to treat
> + * this kernel as PAE.
> + *
> + * LEGACY: PAE (n.b. The legacy interface included a provision to
> + * indicate 'extended-cr3' support allowing L3 page tables to be
> + * placed above 4G. It is assumed that any kernel new enough to use
> + * these ELF notes will include this and therefore "yes" here is
> + * equivalent to "yes[entended-cr3]" in the __xen_guest interface.
> + */
> +#define XEN_ELFNOTE_PAE_MODE 9
> +
> +/*
> + * The features supported/required by this kernel (string).
> + *
> + * The string must consist of a list of feature names (as given in
> + * features.h, without the "XENFEAT_" prefix) separated by '|'
> + * characters. If a feature is required for the kernel to function
> + * then the feature name must be preceded by a '!' character.
> + *
> + * LEGACY: FEATURES
> + */
> +#define XEN_ELFNOTE_FEATURES 10
> +
> +/*
> + * The kernel requires the symbol table to be loaded (string = "yes" or "no")
> + * LEGACY: BSD_SYMTAB (n.b. The legacy treated the presence or absence
> + * of this string as a boolean flag rather than requiring "yes" or
> + * "no".
> + */
> +#define XEN_ELFNOTE_BSD_SYMTAB 11
> +
> +/*
> + * The lowest address the hypervisor hole can begin at (numeric).
> + *
> + * This must not be set higher than HYPERVISOR_VIRT_START. Its presence
> + * also indicates to the hypervisor that the kernel can deal with the
> + * hole starting at a higher address.
> + */
> +#define XEN_ELFNOTE_HV_START_LOW 12
> +
> +/*
> + * List of maddr_t-sized mask/value pairs describing how to recognize
> + * (non-present) L1 page table entries carrying valid MFNs (numeric).
> + */
> +#define XEN_ELFNOTE_L1_MFN_VALID 13
> +
> +/*
> + * Whether or not the guest supports cooperative suspend cancellation.
> + * This is a numeric value.
> + *
> + * Default is 0
> + */
> +#define XEN_ELFNOTE_SUSPEND_CANCEL 14
> +
> +/*
> + * The (non-default) location the initial phys-to-machine map should be
> + * placed at by the hypervisor (Dom0) or the tools (DomU).
> + * The kernel must be prepared for this mapping to be established using
> + * large pages, despite such otherwise not being available to guests.
> + * The kernel must also be able to handle the page table pages used for
> + * this mapping not being accessible through the initial mapping.
> + * (Only x86-64 supports this at present.)
> + */
> +#define XEN_ELFNOTE_INIT_P2M 15
> +
> +/*
> + * Whether or not the guest can deal with being passed an initrd not
> + * mapped through its initial page tables.
> + */
> +#define XEN_ELFNOTE_MOD_START_PFN 16
> +
> +/*
> + * The features supported by this kernel (numeric).
> + *
> + * Other than XEN_ELFNOTE_FEATURES on pre-4.2 Xen, this note allows a
> + * kernel to specify support for features that older hypervisors don't
> + * know about. The set of features 4.2 and newer hypervisors will
> + * consider supported by the kernel is the combination of the sets
> + * specified through this and the string note.
> + *
> + * LEGACY: FEATURES
> + */
> +#define XEN_ELFNOTE_SUPPORTED_FEATURES 17
> +
> +/*
> + * Physical entry point into the kernel.
> + *
> + * 32bit entry point into the kernel. When requested to launch the
> + * guest kernel in a HVM container, Xen will use this entry point to
> + * launch the guest in 32bit protected mode with paging disabled.
> + * Ignored otherwise.
> + */
> +#define XEN_ELFNOTE_PHYS32_ENTRY 18
> +
> +/*
> + * The number of the highest elfnote defined.
> + */
> +#define XEN_ELFNOTE_MAX XEN_ELFNOTE_PHYS32_ENTRY
> +
> +/*
> + * System information exported through crash notes.
> + *
> + * The kexec / kdump code will create one XEN_ELFNOTE_CRASH_INFO
> + * note in case of a system crash. This note will contain various
> + * information about the system, see xen/include/xen/elfcore.h.
> + */
> +#define XEN_ELFNOTE_CRASH_INFO 0x1000001
> +
> +/*
> + * System registers exported through crash notes.
> + *
> + * The kexec / kdump code will create one XEN_ELFNOTE_CRASH_REGS
> + * note per cpu in case of a system crash. This note is architecture
> + * specific and will contain registers not saved in the "CORE" note.
> + * See xen/include/xen/elfcore.h for more information.
> + */
> +#define XEN_ELFNOTE_CRASH_REGS 0x1000002
> +
> +
> +/*
> + * xen dump-core none note.
> + * xm dump-core code will create one XEN_ELFNOTE_DUMPCORE_NONE
> + * in its dump file to indicate that the file is xen dump-core
> + * file. This note doesn't have any other information.
> + * See tools/libxc/xc_core.h for more information.
> + */
> +#define XEN_ELFNOTE_DUMPCORE_NONE 0x2000000
> +
> +/*
> + * xen dump-core header note.
> + * xm dump-core code will create one XEN_ELFNOTE_DUMPCORE_HEADER
> + * in its dump file.
> + * See tools/libxc/xc_core.h for more information.
> + */
> +#define XEN_ELFNOTE_DUMPCORE_HEADER 0x2000001
> +
> +/*
> + * xen dump-core xen version note.
> + * xm dump-core code will create one XEN_ELFNOTE_DUMPCORE_XEN_VERSION
> + * in its dump file. It contains the xen version obtained via the
> + * XENVER hypercall.
> + * See tools/libxc/xc_core.h for more information.
> + */
> +#define XEN_ELFNOTE_DUMPCORE_XEN_VERSION 0x2000002
> +
> +/*
> + * xen dump-core format version note.
> + * xm dump-core code will create one XEN_ELFNOTE_DUMPCORE_FORMAT_VERSION
> + * in its dump file. It contains a format version identifier.
> + * See tools/libxc/xc_core.h for more information.
> + */
> +#define XEN_ELFNOTE_DUMPCORE_FORMAT_VERSION 0x2000003
> +
> +#endif /* __XEN_PUBLIC_ELFNOTE_H__ */
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * tab-width: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
I am not sure that Emacs footer should be copied to GRUB2 source.
Daniel
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