From: Anthony PERARD <anthony.perard@citrix.com> To: xen-devel@lists.xenproject.org Cc: Anthony PERARD <anthony.perard@citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, Wei Liu <wei.liu2@citrix.com> Subject: [PATCH v2] libxc: elf_kernel loader: Remove check for shstrtab Date: Fri, 17 May 2019 12:38:43 +0100 [thread overview] Message-ID: <20190517113843.4598-1-anthony.perard@citrix.com> (raw) In-Reply-To: <20190515114015.25492-1-anthony.perard@citrix.com> This was probably useful as a sanity check when the "__xen_guest" section were not legacy. But now ELF notes are prefered and "should live in a PT_NOTE segment" (elfnote.h). This check is unnecessary as elf_xen_parse() from xen/common/libelf will do the right thing and look for ELFNOTEs in the different places in order of preference. elf_xen_parse() will still be able to also look for the legacy "__xen_guest" section without the check in libxc. This patch would allow to write a simpler ELF header for an OVMF blob (which isn't an ELF) and allow it to be loaded as a PVH kernel. The header only needs to declare two program segments: - one to tell an ELF loader where to put the blob, - one for a Xen ELFNOTE. The ELFNOTE is to comply to the pvh design which wants the XEN_ELFNOTE_PHYS32_ENTRY to declare a blob as compaptible with the PVH boot ABI. Note that without the ELFNOTE, libxc will load an ELF but with the plain ELF loader, which doesn't check for shstrtab. Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> --- Notes: v2: Rework commit message, explain why the check is unnecessary. tools/libxc/xc_dom_elfloader.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/tools/libxc/xc_dom_elfloader.c b/tools/libxc/xc_dom_elfloader.c index 82b5f2ee79..b327db219d 100644 --- a/tools/libxc/xc_dom_elfloader.c +++ b/tools/libxc/xc_dom_elfloader.c @@ -165,15 +165,6 @@ static elf_negerrnoval xc_dom_parse_elf_kernel(struct xc_dom_image *dom) return rc; } - /* Find the section-header strings table. */ - if ( ELF_PTRVAL_INVALID(elf->sec_strtab) ) - { - xc_dom_panic(dom->xch, XC_INVALID_KERNEL, "%s: ELF image" - " has no shstrtab", __FUNCTION__); - rc = -EINVAL; - goto out; - } - /* parse binary and get xen meta info */ elf_parse_binary(elf); if ( elf_xen_parse(elf, &dom->parms) != 0 ) -- Anthony PERARD _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
WARNING: multiple messages have this Message-ID (diff)
From: Anthony PERARD <anthony.perard@citrix.com> To: <xen-devel@lists.xenproject.org> Cc: Anthony PERARD <anthony.perard@citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, Wei Liu <wei.liu2@citrix.com> Subject: [Xen-devel] [PATCH v2] libxc: elf_kernel loader: Remove check for shstrtab Date: Fri, 17 May 2019 12:38:43 +0100 [thread overview] Message-ID: <20190517113843.4598-1-anthony.perard@citrix.com> (raw) Message-ID: <20190517113843.7J2LQEscaEGcWv0R2dPfBoiWkbfn4GBIeNHcqgHSwPQ@z> (raw) In-Reply-To: <20190515114015.25492-1-anthony.perard@citrix.com> This was probably useful as a sanity check when the "__xen_guest" section were not legacy. But now ELF notes are prefered and "should live in a PT_NOTE segment" (elfnote.h). This check is unnecessary as elf_xen_parse() from xen/common/libelf will do the right thing and look for ELFNOTEs in the different places in order of preference. elf_xen_parse() will still be able to also look for the legacy "__xen_guest" section without the check in libxc. This patch would allow to write a simpler ELF header for an OVMF blob (which isn't an ELF) and allow it to be loaded as a PVH kernel. The header only needs to declare two program segments: - one to tell an ELF loader where to put the blob, - one for a Xen ELFNOTE. The ELFNOTE is to comply to the pvh design which wants the XEN_ELFNOTE_PHYS32_ENTRY to declare a blob as compaptible with the PVH boot ABI. Note that without the ELFNOTE, libxc will load an ELF but with the plain ELF loader, which doesn't check for shstrtab. Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> --- Notes: v2: Rework commit message, explain why the check is unnecessary. tools/libxc/xc_dom_elfloader.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/tools/libxc/xc_dom_elfloader.c b/tools/libxc/xc_dom_elfloader.c index 82b5f2ee79..b327db219d 100644 --- a/tools/libxc/xc_dom_elfloader.c +++ b/tools/libxc/xc_dom_elfloader.c @@ -165,15 +165,6 @@ static elf_negerrnoval xc_dom_parse_elf_kernel(struct xc_dom_image *dom) return rc; } - /* Find the section-header strings table. */ - if ( ELF_PTRVAL_INVALID(elf->sec_strtab) ) - { - xc_dom_panic(dom->xch, XC_INVALID_KERNEL, "%s: ELF image" - " has no shstrtab", __FUNCTION__); - rc = -EINVAL; - goto out; - } - /* parse binary and get xen meta info */ elf_parse_binary(elf); if ( elf_xen_parse(elf, &dom->parms) != 0 ) -- Anthony PERARD _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2019-05-17 11:38 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-05-15 11:40 [PATCH] libxc: elf_kernel loader: Remove check for shstrtab Anthony PERARD 2019-05-15 11:40 ` [Xen-devel] " Anthony PERARD 2019-05-15 12:02 ` Wei Liu 2019-05-15 12:02 ` [Xen-devel] " Wei Liu 2019-05-15 12:07 ` Andrew Cooper 2019-05-15 12:07 ` [Xen-devel] " Andrew Cooper 2019-05-15 12:09 ` Wei Liu 2019-05-15 12:09 ` [Xen-devel] " Wei Liu 2019-05-15 12:55 ` Anthony PERARD 2019-05-15 12:55 ` [Xen-devel] " Anthony PERARD 2019-05-16 13:23 ` Wei Liu 2019-05-16 13:23 ` [Xen-devel] " Wei Liu 2019-05-16 13:38 ` Andrew Cooper 2019-05-16 13:38 ` [Xen-devel] " Andrew Cooper 2019-05-17 11:38 ` Anthony PERARD [this message] 2019-05-17 11:38 ` [Xen-devel] [PATCH v2] " Anthony PERARD
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