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MIPS: Avoid using .set mips0 to restore ISA

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We currently have 2 commonly used methods for switching ISA within
assembly code, then restoring the original ISA.

  1) Using a pair of .set push & .set pop directives. For example:

     .set	push
     .set	mips32r2
     <some_insn>
     .set	pop

  2) Using .set mips0 to restore the ISA originally specified on the
     command line. For example:

     .set	mips32r2
     <some_insn>
     .set	mips0

Unfortunately method 2 does not work with nanoMIPS toolchains, where the
assembler rejects the .set mips0 directive like so:

     Error: cannot change ISA from nanoMIPS to mips0

In preparation for supporting nanoMIPS builds, switch all instances of
method 2 in generic non-platform-specific code to use push & pop as in
method 1 instead. The .set push & .set pop is arguably cleaner anyway,
and if nothing else it's good to consistently use one method.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21037/
Cc: linux-mips@linux-mips.org
This commit is contained in:
Paul Burton
2018-11-08 20:14:38 +00:00
parent 183b40f992
commit 378ed6f0e3
16 changed files with 121 additions and 68 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
arch/mips/include/asm/cmpxchg.h
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@@ -47,9 +47,10 @@ extern unsigned long __xchg_called_with_bad_pointer(void)
__asm__ __volatile__( \
" .set push \n" \
" .set noat \n" \
" .set push \n" \
" .set " MIPS_ISA_ARCH_LEVEL " \n" \
"1: " ld " %0, %2 # __xchg_asm \n" \
" .set mips0 \n" \
" .set pop \n" \
" move $1, %z3 \n" \
" .set " MIPS_ISA_ARCH_LEVEL " \n" \
" " st " $1, %1 \n" \
@@ -117,10 +118,11 @@ static inline unsigned long __xchg(volatile void *ptr, unsigned long x,
__asm__ __volatile__( \
" .set push \n" \
" .set noat \n" \
" .set push \n" \
" .set "MIPS_ISA_ARCH_LEVEL" \n" \
"1: " ld " %0, %2 # __cmpxchg_asm \n" \
" bne %0, %z3, 2f \n" \
" .set mips0 \n" \
" .set pop \n" \
" move $1, %z4 \n" \
" .set "MIPS_ISA_ARCH_LEVEL" \n" \
" " st " $1, %1 \n" \