[PATCH] x86: fix GET_STACK_END

[PATCH] x86: fix GET_STACK_END

[Wei Liu]

AIUI the purpose of having the .if directive is to make GET_STACK_END
work with any general purpose registers. The code as-is would produce
the wrong result for r8. Fix it.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
---
 xen/include/asm-x86/asm_defns.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/include/asm-x86/asm_defns.h b/xen/include/asm-x86/asm_defns.h
index d2d91ca1fa..6a2b833db6 100644
--- a/xen/include/asm-x86/asm_defns.h
+++ b/xen/include/asm-x86/asm_defns.h
@@ -120,7 +120,7 @@ void ret_from_intr(void);
 
 #define STACK_CPUINFO_FIELD(field) (1 - CPUINFO_sizeof + CPUINFO_##field)
 #define GET_STACK_END(reg)                        \
-        .if .Lr##reg > 8;                         \
+        .if .Lr##reg >= 8;                        \
         movq $STACK_SIZE-1, %r##reg;              \
         .else;                                    \
         movl $STACK_SIZE-1, %e##reg;              \
-- 
2.11.0


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Re: [PATCH] x86: fix GET_STACK_END

[Andrew Cooper]

________________________________________
From: Wei Liu [wei.liu2@citrix.com]
Sent: 24 January 2018 20:26
To: Xen-devel
Cc: Wei Liu; Jan Beulich; Andrew Cooper
Subject: [PATCH] x86: fix GET_STACK_END

AIUI the purpose of having the .if directive is to make GET_STACK_END
work with any general purpose registers. The code as-is would produce
the wrong result for r8. Fix it.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>

Oops.  Acked-by: Andrew Cooper ≤andrew.cooper3@citrix.com≥

---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
---
 xen/include/asm-x86/asm_defns.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/include/asm-x86/asm_defns.h b/xen/include/asm-x86/asm_defns.h
index d2d91ca1fa..6a2b833db6 100644
--- a/xen/include/asm-x86/asm_defns.h
+++ b/xen/include/asm-x86/asm_defns.h
@@ -120,7 +120,7 @@ void ret_from_intr(void);

 #define STACK_CPUINFO_FIELD(field) (1 - CPUINFO_sizeof + CPUINFO_##field)
 #define GET_STACK_END(reg)                        \
-        .if .Lr##reg > 8;                         \
+        .if .Lr##reg >= 8;                        \
         movq $STACK_SIZE-1, %r##reg;              \
         .else;                                    \
         movl $STACK_SIZE-1, %e##reg;              \
--
2.11.0


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Re: [PATCH] x86: fix GET_STACK_END

[Jan Beulich]

>>> On 24.01.18 at 21:48, <Andrew.Cooper3@citrix.com> wrote:
> From: Wei Liu [wei.liu2@citrix.com]
> Sent: 24 January 2018 20:26
> 
> AIUI the purpose of having the .if directive is to make GET_STACK_END
> work with any general purpose registers. The code as-is would produce
> the wrong result for r8. Fix it.
> 
> Signed-off-by: Wei Liu <wei.liu2@citrix.com>
> 
> Oops.  Acked-by: Andrew Cooper ≤andrew.cooper3@citrix.com≥

Oops indeed - luckily the build would have failed in such a case,
rather than producing a broken binary.

Jan

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