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ARM: 8852/1: uaccess: use unified assembler language syntax 

Convert the conditional infix to a postfix to make sure this inline
assembly is unified syntax. Since gcc assumes non-unified syntax
when emitting ARM instructions, make sure to define the syntax as
unified.

This allows to use LLVM's integrated assembler.

Additionally, for GCC ".syntax unified" for inline assembly.
When compiling non-Thumb2 GCC always emits a ".syntax divided"
at the beginning of the inline assembly which makes the
assembler fail. Since GCC 5 there is the -masm-syntax-unified
GCC option which make GCC assume unified syntax asm and hence
emits ".syntax unified" even in ARM mode. However, the option
is broken since GCC version 6 (see GCC PR88648 [1]). Work
around by adding ".syntax unified" as part of the inline
assembly.

[0] https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html#index-masm-syntax-unified
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88648

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Stefan Agner 2019-03-23 12:10:44 +01:00 committed by Russell King
parent a6c9e96bf8
commit fe09d9c641
1 changed files with 2 additions and 1 deletions
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3
arch/arm/include/asm/uaccess.h
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@ -112,10 +112,11 @@ static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
unsigned long tmp;
asm volatile(
" .syntax unified\n"
" sub %1, %3, #1\n"
" subs %1, %1, %0\n"
" addhs %1, %1, #1\n"
" subhss %1, %1, %2\n"
" subshs %1, %1, %2\n"
" movlo %0, #0\n"
: "+r" (safe_ptr), "=&r" (tmp)
: "r" (size), "r" (current_thread_info()->addr_limit)