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Commit | Line | Data |
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22b74881 GKH |
1 | From foo@baz Wed Nov 21 18:50:39 CET 2018 |
2 | From: Matthias Kaehlcke <mka@chromium.org> | |
3 | Date: Mon, 1 May 2017 15:47:41 -0700 | |
4 | Subject: x86/mm/kaslr: Use the _ASM_MUL macro for multiplication to work around Clang incompatibility | |
5 | ||
6 | From: Matthias Kaehlcke <mka@chromium.org> | |
7 | ||
8 | commit 121843eb02a6e2fa30aefab64bfe183c97230c75 upstream. | |
9 | ||
10 | The constraint "rm" allows the compiler to put mix_const into memory. | |
11 | When the input operand is a memory location then MUL needs an operand | |
12 | size suffix, since Clang can't infer the multiplication width from the | |
13 | operand. | |
14 | ||
15 | Add and use the _ASM_MUL macro which determines the operand size and | |
16 | resolves to the NUL instruction with the corresponding suffix. | |
17 | ||
18 | This fixes the following error when building with clang: | |
19 | ||
20 | CC arch/x86/lib/kaslr.o | |
21 | /tmp/kaslr-dfe1ad.s: Assembler messages: | |
22 | /tmp/kaslr-dfe1ad.s:182: Error: no instruction mnemonic suffix given and no register operands; can't size instruction | |
23 | ||
24 | Signed-off-by: Matthias Kaehlcke <mka@chromium.org> | |
25 | Cc: Grant Grundler <grundler@chromium.org> | |
26 | Cc: Greg Hackmann <ghackmann@google.com> | |
27 | Cc: Kees Cook <keescook@chromium.org> | |
28 | Cc: Linus Torvalds <torvalds@linux-foundation.org> | |
29 | Cc: Michael Davidson <md@google.com> | |
30 | Cc: Peter Zijlstra <peterz@infradead.org> | |
31 | Cc: Thomas Gleixner <tglx@linutronix.de> | |
32 | Link: http://lkml.kernel.org/r/20170501224741.133938-1-mka@chromium.org | |
33 | Signed-off-by: Ingo Molnar <mingo@kernel.org> | |
34 | [nc: Apply to aslr.c in get_random_long as the kaslr shift didn't happen | |
35 | until 4.8 in commit d899a7d146a2] | |
36 | Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> | |
37 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
38 | --- | |
39 | arch/x86/boot/compressed/aslr.c | 3 ++- | |
40 | arch/x86/include/asm/asm.h | 1 + | |
41 | 2 files changed, 3 insertions(+), 1 deletion(-) | |
42 | ||
43 | --- a/arch/x86/boot/compressed/aslr.c | |
44 | +++ b/arch/x86/boot/compressed/aslr.c | |
45 | @@ -1,5 +1,6 @@ | |
46 | #include "misc.h" | |
47 | ||
48 | +#include <asm/asm.h> | |
49 | #include <asm/msr.h> | |
50 | #include <asm/archrandom.h> | |
51 | #include <asm/e820.h> | |
52 | @@ -94,7 +95,7 @@ static unsigned long get_random_long(voi | |
53 | } | |
54 | ||
55 | /* Circular multiply for better bit diffusion */ | |
56 | - asm("mul %3" | |
57 | + asm(_ASM_MUL "%3" | |
58 | : "=a" (random), "=d" (raw) | |
59 | : "a" (random), "rm" (mix_const)); | |
60 | random += raw; | |
61 | --- a/arch/x86/include/asm/asm.h | |
62 | +++ b/arch/x86/include/asm/asm.h | |
63 | @@ -34,6 +34,7 @@ | |
64 | #define _ASM_ADD __ASM_SIZE(add) | |
65 | #define _ASM_SUB __ASM_SIZE(sub) | |
66 | #define _ASM_XADD __ASM_SIZE(xadd) | |
67 | +#define _ASM_MUL __ASM_SIZE(mul) | |
68 | ||
69 | #define _ASM_AX __ASM_REG(ax) | |
70 | #define _ASM_BX __ASM_REG(bx) |