In difference to gas clang doesn't seem to infer the size from the
operands. Add and use the _ASM_MUL macro which determines the operand
size and resolves to the 'mul' instruction with the corresponding
suffix.
This fixes the following error when building with clang:
CC arch/x86/lib/kaslr.o
/tmp/kaslr-dfe1ad.s: Assembler messages:
/tmp/kaslr-dfe1ad.s:182: Error: no instruction mnemonic suffix given and
no register operands; can't size instruction
Signed-off-by: Matthias Kaehlcke <m...@chromium.org>
---
Changes in v2:
- use _ASM_MUL instead of #ifdef
- updated commit message
arch/x86/include/asm/asm.h | 1 +
arch/x86/lib/kaslr.c | 3 ++-
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 7acb51c49fec..7a9df3beb89b 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -32,6 +32,7 @@
#define _ASM_ADD __ASM_SIZE(add)
#define _ASM_SUB __ASM_SIZE(sub)
#define _ASM_XADD __ASM_SIZE(xadd)
+#define _ASM_MUL __ASM_SIZE(mul)
#define _ASM_AX __ASM_REG(ax)
#define _ASM_BX __ASM_REG(bx)
diff --git a/arch/x86/lib/kaslr.c b/arch/x86/lib/kaslr.c
index 121f59c6ee54..0c7fe444dcdd 100644
--- a/arch/x86/lib/kaslr.c
+++ b/arch/x86/lib/kaslr.c
@@ -5,6 +5,7 @@
* kernel starts. This file is included in the compressed kernel and
* normally linked in the regular.
*/
+#include <asm/asm.h>
#include <asm/kaslr.h>
#include <asm/msr.h>
#include <asm/archrandom.h>
@@ -79,7 +80,7 @@ unsigned long kaslr_get_random_long(const char *purpose)
}
/* Circular multiply for better bit diffusion */
- asm("mul %3"
+ asm(_ASM_MUL "%3"
: "=a" (random), "=d" (raw)
: "a" (random), "rm" (mix_const));
random += raw;
--
2.13.0.rc0.306.g87b477812d-goog
