Xen i386 xen-head.S fix sections mixup xen-head.S does not come back to the data section, leaving the text section as current section. It causes problems with a slightly enhanced DEBUG_RODATA that supports CONFIG_HOTPLUG and bringing a CPU up after the text has been marked read-only: reference to early_gdt_descr causes a page fault. It applies on 2.6.22-rc2-mm2. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> CC: jeremy@xensource.com CC: chrisw@sous-sol.org CC: virtualization@lists.osdl.org CC: xen-devel@lists.xensource.com --- arch/i386/xen/xen-head.S | 2 ++ 1 file changed, 2 insertions(+) Index: linux-2.6-lttng/arch/i386/xen/xen-head.S ==================================================================--- linux-2.6-lttng.orig/arch/i386/xen/xen-head.S 2007-08-19 22:45:58.000000000 -0400 +++ linux-2.6-lttng/arch/i386/xen/xen-head.S 2007-08-19 22:46:19.000000000 -0400 @@ -13,6 +13,7 @@ ENTRY(startup_xen) cld movl $(init_thread_union+THREAD_SIZE),%esp jmp xen_start_kernel + .previous .pushsection ".bss.page_aligned" .align PAGE_SIZE_asm @@ -34,5 +35,6 @@ ENTRY(hypercall_page) ELFNOTE(Xen, XEN_ELFNOTE_PAE_MODE, .asciz "no") #endif ELFNOTE(Xen, XEN_ELFNOTE_LOADER, .asciz "generic") + .previous #endif /*CONFIG_XEN */ -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
Mathieu Desnoyers wrote:> Xen i386 xen-head.S fix sections mixup > > xen-head.S does not come back to the data section, leaving the text section > as current section. It causes problems with a slightly enhanced DEBUG_RODATA > that supports CONFIG_HOTPLUG and bringing a CPU up after the text has been > marked read-only: reference to early_gdt_descr causes a page fault. >Thanks. It should be using pushsection/popsection. J
Mathieu Desnoyers
2007-Aug-20 10:19 UTC
[PATCH] Xen i386 xen-head.S fix sections mixup (updated)
Xen i386 xen-head.S fix sections mixup xen-head.S does not come back to the data section, leaving the text section as current section. It causes problems with a slightly enhanced DEBUG_RODATA that supports CONFIG_HOTPLUG and bringing a CPU up after the text has been marked read-only: reference to early_gdt_descr causes a page fault. Update: It should be using pushsection/popsection. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> CC: jeremy@xensource.com CC: chrisw@sous-sol.org CC: virtualization@lists.osdl.org CC: xen-devel@lists.xensource.com --- arch/i386/xen/xen-head.S | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) Index: linux-2.6-lttng/arch/i386/xen/xen-head.S ==================================================================--- linux-2.6-lttng.orig/arch/i386/xen/xen-head.S 2007-08-20 00:22:16.000000000 -0400 +++ linux-2.6-lttng/arch/i386/xen/xen-head.S 2007-08-20 13:02:38.000000000 -0400 @@ -7,20 +7,21 @@ #include <asm/boot.h> #include <xen/interface/elfnote.h> - .section .init.text +.pushsection .init.text ENTRY(startup_xen) movl %esi,xen_start_info cld movl $(init_thread_union+THREAD_SIZE),%esp jmp xen_start_kernel +.popsection -.pushsection ".bss.page_aligned" +.pushsection .bss.page_aligned .align PAGE_SIZE_asm ENTRY(hypercall_page) .skip 0x1000 .popsection - .section .text +.pushsection .text ELFNOTE(Xen, XEN_ELFNOTE_GUEST_OS, .asciz "linux") ELFNOTE(Xen, XEN_ELFNOTE_GUEST_VERSION, .asciz "2.6") ELFNOTE(Xen, XEN_ELFNOTE_XEN_VERSION, .asciz "xen-3.0") @@ -34,5 +35,6 @@ ENTRY(hypercall_page) ELFNOTE(Xen, XEN_ELFNOTE_PAE_MODE, .asciz "no") #endif ELFNOTE(Xen, XEN_ELFNOTE_LOADER, .asciz "generic") +.popsection #endif /*CONFIG_XEN */ -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
Jeremy Fitzhardinge
2007-Aug-20 10:35 UTC
[PATCH] Xen i386 xen-head.S fix sections mixup (updated)
Mathieu Desnoyers wrote:> Xen i386 xen-head.S fix sections mixup > > xen-head.S does not come back to the data section, leaving the text section > as current section. It causes problems with a slightly enhanced DEBUG_RODATA > that supports CONFIG_HOTPLUG and bringing a CPU up after the text has been > marked read-only: reference to early_gdt_descr causes a page fault. > > Update: > > It should be using pushsection/popsection. >Looks good, with one caveat below. Acked-by: Jeremy Fitzhardinge <jeremy@xensource.com>> - .section .text > +.pushsection .text > ELFNOTE(Xen, XEN_ELFNOTE_GUEST_OS, .asciz "linux") > ELFNOTE(Xen, XEN_ELFNOTE_GUEST_VERSION, .asciz "2.6") > ELFNOTE(Xen, XEN_ELFNOTE_XEN_VERSION, .asciz "xen-3.0") > @@ -34,5 +35,6 @@ ENTRY(hypercall_page) > ELFNOTE(Xen, XEN_ELFNOTE_PAE_MODE, .asciz "no") > #endif > ELFNOTE(Xen, XEN_ELFNOTE_LOADER, .asciz "generic") > +.popsection >Actually, the push/popsections around the ELFNOTEs are redundant; ELFNOTE() does its own push/popsection to put things into the appropriate .note* section anyway. J
Mathieu Desnoyers
2007-Aug-20 12:05 UTC
[PATCH] Xen i386 xen-head.S fix sections mixup (update 2)
Xen i386 xen-head.S fix sections mixup xen-head.S does not come back to the data section, leaving the text section as current section. It causes problems with a slightly enhanced DEBUG_RODATA that supports CONFIG_HOTPLUG and bringing a CPU up after the text has been marked read-only: reference to early_gdt_descr causes a page fault. Updates: - It should be using pushsection/popsection. - Actually, the push/popsections around the ELFNOTEs are redundant; ELFNOTE() does its own push/popsection to put things into the appropriate .note* section anyway. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Acked-by: Jeremy Fitzhardinge <jeremy@xensource.com> CC: chrisw@sous-sol.org CC: virtualization@lists.osdl.org CC: xen-devel@lists.xensource.com --- arch/i386/xen/xen-head.S | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) Index: linux-2.6-lttng/arch/i386/xen/xen-head.S ==================================================================--- linux-2.6-lttng.orig/arch/i386/xen/xen-head.S 2007-08-20 00:22:16.000000000 -0400 +++ linux-2.6-lttng/arch/i386/xen/xen-head.S 2007-08-20 15:00:55.000000000 -0400 @@ -7,20 +7,20 @@ #include <asm/boot.h> #include <xen/interface/elfnote.h> - .section .init.text +.pushsection .init.text ENTRY(startup_xen) movl %esi,xen_start_info cld movl $(init_thread_union+THREAD_SIZE),%esp jmp xen_start_kernel +.popsection -.pushsection ".bss.page_aligned" +.pushsection .bss.page_aligned .align PAGE_SIZE_asm ENTRY(hypercall_page) .skip 0x1000 .popsection - .section .text ELFNOTE(Xen, XEN_ELFNOTE_GUEST_OS, .asciz "linux") ELFNOTE(Xen, XEN_ELFNOTE_GUEST_VERSION, .asciz "2.6") ELFNOTE(Xen, XEN_ELFNOTE_XEN_VERSION, .asciz "xen-3.0") -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68