From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xenproject.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
"Jan Beulich" <JBeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>
Subject: [PATCH] xen/x86: Work around Clang code generation bug with asm parameters
Date: Wed, 11 Nov 2020 12:45:12 +0000 [thread overview]
Message-ID: <20201111124512.2268-1-andrew.cooper3@citrix.com> (raw)
Clang 9 and later don't handle the clobber of %r10 correctly in
_hypercall64_4(). See https://bugs.llvm.org/show_bug.cgi?id=48122
Rewrite the logic to use the "+r" form, rather than using separate input and
output specifiers, which works around the issue. For consistency, adjust all
operand handling.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Wei Liu <wl@xen.org>
---
xen/include/asm-x86/guest/xen-hcall.h | 35 ++++++++++++++++-------------------
1 file changed, 16 insertions(+), 19 deletions(-)
diff --git a/xen/include/asm-x86/guest/xen-hcall.h b/xen/include/asm-x86/guest/xen-hcall.h
index 03d5868a9e..3240d9807b 100644
--- a/xen/include/asm-x86/guest/xen-hcall.h
+++ b/xen/include/asm-x86/guest/xen-hcall.h
@@ -39,53 +39,50 @@
#define _hypercall64_1(type, hcall, a1) \
({ \
- long res, tmp__; \
+ long res, _a1 = (long)(a1); \
asm volatile ( \
"call hypercall_page + %c[offset]" \
- : "=a" (res), "=D" (tmp__) ASM_CALL_CONSTRAINT \
- : [offset] "i" (hcall * 32), \
- "1" ((long)(a1)) \
+ : "=a" (res), "+D" (_a1) ASM_CALL_CONSTRAINT \
+ : [offset] "i" (hcall * 32) \
: "memory" ); \
(type)res; \
})
#define _hypercall64_2(type, hcall, a1, a2) \
({ \
- long res, tmp__; \
+ long res, _a1 = (long)(a1), _a2 = (long)(a2); \
asm volatile ( \
"call hypercall_page + %c[offset]" \
- : "=a" (res), "=D" (tmp__), "=S" (tmp__) \
+ : "=a" (res), "+D" (_a1), "+S" (_a2) \
ASM_CALL_CONSTRAINT \
- : [offset] "i" (hcall * 32), \
- "1" ((long)(a1)), "2" ((long)(a2)) \
+ : [offset] "i" (hcall * 32) \
: "memory" ); \
(type)res; \
})
#define _hypercall64_3(type, hcall, a1, a2, a3) \
({ \
- long res, tmp__; \
+ long res, _a1 = (long)(a1), _a2 = (long)(a2), \
+ _a3 = (long)(a3); \
asm volatile ( \
"call hypercall_page + %c[offset]" \
- : "=a" (res), "=D" (tmp__), "=S" (tmp__), "=d" (tmp__) \
+ : "=a" (res), "+D" (_a1), "+S" (_a2), "+d" (_a3) \
ASM_CALL_CONSTRAINT \
- : [offset] "i" (hcall * 32), \
- "1" ((long)(a1)), "2" ((long)(a2)), "3" ((long)(a3)) \
+ : [offset] "i" (hcall * 32) \
: "memory" ); \
(type)res; \
})
#define _hypercall64_4(type, hcall, a1, a2, a3, a4) \
({ \
- long res, tmp__; \
- register long _a4 asm ("r10") = ((long)(a4)); \
+ long res, _a1 = (long)(a1), _a2 = (long)(a2), \
+ _a3 = (long)(a3); \
+ register long _a4 asm ("r10") = (long)(a4); \
asm volatile ( \
"call hypercall_page + %c[offset]" \
- : "=a" (res), "=D" (tmp__), "=S" (tmp__), "=d" (tmp__), \
- "=&r" (tmp__) ASM_CALL_CONSTRAINT \
- : [offset] "i" (hcall * 32), \
- "1" ((long)(a1)), "2" ((long)(a2)), "3" ((long)(a3)), \
- "4" (_a4) \
+ : "=a" (res), "+D" (_a1), "+S" (_a2), "+d" (_a3) \
+ "+r" (_a4) ASM_CALL_CONSTRAINT \
+ : [offset] "i" (hcall * 32) \
: "memory" ); \
(type)res; \
})
--
2.11.0
next reply other threads:[~2020-11-11 12:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-11 12:45 Andrew Cooper [this message]
2020-11-11 15:11 ` [PATCH] xen/x86: Work around Clang code generation bug with asm parameters Jan Beulich
2020-11-11 20:01 ` Andrew Cooper
2020-11-12 8:14 ` Jan Beulich
2020-11-27 10:22 ` Jan Beulich
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