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| author | Markos Chandras <markos.chandras@imgtec.com> | 2014-12-03 15:37:32 +0300 |
|---|---|---|
| committer | Markos Chandras <markos.chandras@imgtec.com> | 2015-02-17 18:37:37 +0300 |
| commit | 7c151d3d5d7a032e08dbe86ad6088622391bf13e (patch) | |
| tree | 362d5ffcf8fea7c26373750efb106ca1e41c275f /arch/mips/kernel/entry.S | |
| parent | b0a668fb2038d846a466c7a16a358d874002b697 (diff) | |
| download | linux-7c151d3d5d7a032e08dbe86ad6088622391bf13e.tar.xz | |
MIPS: Make use of the ERETNC instruction on MIPS R6
The ERETNC instruction, introduced in MIPS R5, is similar to the ERET
one, except it does not clear the LLB bit in the LLADDR register.
This feature is necessary to safely emulate R2 LL/SC instructions.
However, on context switches, we need to clear the LLAddr/LLB bit
in order to make sure that an SC instruction from the new thread
will never succeed if it happens to interrupt an LL operation on the
same address from the previous thread.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Diffstat (limited to 'arch/mips/kernel/entry.S')
| -rw-r--r-- | arch/mips/kernel/entry.S | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/mips/kernel/entry.S b/arch/mips/kernel/entry.S index d5ab21c3fd12..af41ba6db960 100644 --- a/arch/mips/kernel/entry.S +++ b/arch/mips/kernel/entry.S @@ -46,6 +46,11 @@ resume_userspace: local_irq_disable # make sure we dont miss an # interrupt setting need_resched # between sampling and return +#ifdef CONFIG_MIPSR2_TO_R6_EMULATOR + lw k0, TI_R2_EMUL_RET($28) + bnez k0, restore_all_from_r2_emul +#endif + LONG_L a2, TI_FLAGS($28) # current->work andi t0, a2, _TIF_WORK_MASK # (ignoring syscall_trace) bnez t0, work_pending @@ -114,6 +119,19 @@ restore_partial: # restore partial frame RESTORE_SP_AND_RET .set at +#ifdef CONFIG_MIPSR2_TO_R6_EMULATOR +restore_all_from_r2_emul: # restore full frame + .set noat + sw zero, TI_R2_EMUL_RET($28) # reset it + RESTORE_TEMP + RESTORE_AT + RESTORE_STATIC + RESTORE_SOME + LONG_L sp, PT_R29(sp) + eretnc + .set at +#endif + work_pending: andi t0, a2, _TIF_NEED_RESCHED # a2 is preloaded with TI_FLAGS beqz t0, work_notifysig |