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SubjectRe: [PATCH 7/8] x86/xen: Add unwind hint annotations
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On 08/31/2017, 10:23 PM, Josh Poimboeuf wrote:
> Add unwind hint annotations to the xen head code so the ORC unwinder can
> read head_64.o.

xen-head.S is included also in head_32.S, so we see:
arch/x86/kernel/../../x86/xen/xen-head.S:47: Error: no such instruction:
`unwind_hint_empty'
scripts/Makefile.build:413: recipe for target
'arch/x86/kernel/head_32.o' failed

To fix this, I use:

--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -25,6 +25,7 @@
#include <asm/bootparam.h>
#include <asm/export.h>
#include <asm/pgtable_32.h>
+#include "../entry/calling.h"

/* Physical address */
#define pa(X) ((X) - __PAGE_OFFSET)

> hypercall_page needs empty annotations at 32-byte intervals to match the
> 'xen_hypercall_*' ELF functions at those locations.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> ---
> arch/x86/xen/xen-head.S | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
> index 9753225289e8..8f9741cbb32f 100644
> --- a/arch/x86/xen/xen-head.S
> +++ b/arch/x86/xen/xen-head.S
> @@ -19,6 +19,7 @@
> #ifdef CONFIG_XEN_PV
> __INIT
> ENTRY(startup_xen)
> + UNWIND_HINT_EMPTY
> cld
>
> /* Clear .bss */
> @@ -40,7 +41,10 @@ END(startup_xen)
> .pushsection .text
> .balign PAGE_SIZE
> ENTRY(hypercall_page)
> - .skip PAGE_SIZE
> + .rept (PAGE_SIZE / 32)
> + UNWIND_HINT_EMPTY
> + .skip 32
> + .endr
>
> #define HYPERCALL(n) \
> .equ xen_hypercall_##n, hypercall_page + __HYPERVISOR_##n * 32; \
>


--
js
suse labs

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