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ARM: 8851/1: add TUSERCOND() macro for conditional postfix 

Unified assembly syntax requires conditionals to be postfixes.
TUSER() currently only takes a single argument which then gets
appended t (with translation) on every instruction.

This fixes a build error when using LLVM's integrated assembler:
  In file included from kernel/futex.c:72:
  ./arch/arm/include/asm/futex.h:116:3: error: invalid instruction, did you mean: strt?
          "2:     " TUSER(streq) "        %3, [%4]n"
           ^
  <inline asm>:5:4: note: instantiated into assembly here
  2:      streqt  r2, [r4]
          ^~~~~~

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 12:09:49 +01:00 committed by Russell King
parent 9e98c678c2
commit a6c9e96bf8
2 changed files with 6 additions and 3 deletions
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6
arch/arm/include/asm/domain.h
View File

@ -133,9 +133,11 @@ static inline void modify_domain(unsigned dom, unsigned type) { }
* instructions (inline assembly)
*/
#ifdef CONFIG_CPU_USE_DOMAINS
#define TUSER(instr) #instr "t"
#define TUSER(instr) TUSERCOND(instr, )
#define TUSERCOND(instr, cond) #instr "t" #cond
#else
#define TUSER(instr) #instr
#define TUSER(instr) TUSERCOND(instr, )
#define TUSERCOND(instr, cond) #instr #cond
#endif
#else /* __ASSEMBLY__ */

3
arch/arm/include/asm/futex.h
View File

@ -110,10 +110,11 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
preempt_disable();
__ua_flags = uaccess_save_and_enable();
__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
" .syntax unified\n"
"1: " TUSER(ldr) " %1, [%4]\n"
" teq %1, %2\n"
" it eq @ explicit IT needed for the 2b label\n"
"2: " TUSER(streq) " %3, [%4]\n"
"2: " TUSERCOND(str, eq) " %3, [%4]\n"
__futex_atomic_ex_table("%5")
: "+r" (ret), "=&r" (val)
: "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)