In the previous TM code, trecheckpoint was being executed in the middle of an exception, thus, DSCR was being restored to default kernel DSCR value after trecheckpoint was done.
With this current patchset, trecheckpoint is executed just before getting to userspace, at ret_from_except_lite, for example. Thus, we do not need to set default kernel DSCR value anymore, as we are leaving kernel space. It is OK to keep the checkpointed DSCR value into the live SPR, mainly because the transaction is doomed and it will fail soon (after RFID), so, continuing with the pre-checkpointed DSCR value is what seems correct. That said, we must set the DSCR value that will be used in userspace now. Current trecheckpoint() function sets it to the pre-checkpointed value prior to lines being changed in this patch, so, removing these lines would keep the pre-checkpointed values. Important to say that we do not need to do the same thing with tm_reclaim, since it already set the DSCR to the default value, after TRECLAIM is called, in the following lines: /* Load CPU's default DSCR */ ld r0, PACA_DSCR_DEFAULT(r13) mtspr SPRN_DSCR, r0 Signed-off-by: Breno Leitao <lei...@debian.org> --- arch/powerpc/kernel/tm.S | 4 ---- 1 file changed, 4 deletions(-) diff --git a/arch/powerpc/kernel/tm.S b/arch/powerpc/kernel/tm.S index 6bffbc5affe7..5427eda69846 100644 --- a/arch/powerpc/kernel/tm.S +++ b/arch/powerpc/kernel/tm.S @@ -493,10 +493,6 @@ restore_gprs: mtlr r0 ld r2, STK_GOT(r1) - /* Load CPU's default DSCR */ - ld r0, PACA_DSCR_DEFAULT(r13) - mtspr SPRN_DSCR, r0 - blr /* ****************************************************************** */ -- 2.19.0