On Tue, 3 Jul 2018 08:08:14 +1000 Nicholas Piggin <npig...@gmail.com> wrote:
> On Mon, 02 Jul 2018 11:17:06 +0530 > Mahesh J Salgaonkar <mah...@linux.vnet.ibm.com> wrote: > > > From: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com> > > > > On pseries, as of today system crashes if we get a machine check > > exceptions due to SLB errors. These are soft errors and can be > > fixed by flushing the SLBs so the kernel can continue to function > > instead of system crash. We do this in real mode before turning on > > MMU. Otherwise we would run into nested machine checks. This patch > > now fetches the rtas error log in real mode and flushes the SLBs on > > SLB errors. > > > > Signed-off-by: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com> > > --- > > arch/powerpc/include/asm/book3s/64/mmu-hash.h | 1 > > arch/powerpc/include/asm/machdep.h | 1 > > arch/powerpc/kernel/exceptions-64s.S | 42 > > +++++++++++++++++++++ arch/powerpc/kernel/mce.c > > | 16 +++++++- arch/powerpc/mm/slb.c | > > 6 +++ arch/powerpc/platforms/powernv/opal.c | 1 > > arch/powerpc/platforms/pseries/pseries.h | 1 > > arch/powerpc/platforms/pseries/ras.c | 51 > > +++++++++++++++++++++++++ > > arch/powerpc/platforms/pseries/setup.c | 1 9 files > > changed, 116 insertions(+), 4 deletions(-) > > > > +TRAMP_REAL_BEGIN(machine_check_pSeries_early) > > +BEGIN_FTR_SECTION > > + EXCEPTION_PROLOG_1(PACA_EXMC, NOTEST, 0x200) > > + mr r10,r1 /* Save r1 */ > > + ld r1,PACAMCEMERGSP(r13) /* Use MC emergency > > stack */ > > + subi r1,r1,INT_FRAME_SIZE /* alloc stack > > frame */ > > + mfspr r11,SPRN_SRR0 /* Save SRR0 */ > > + mfspr r12,SPRN_SRR1 /* Save SRR1 */ > > + EXCEPTION_PROLOG_COMMON_1() > > + EXCEPTION_PROLOG_COMMON_2(PACA_EXMC) > > + EXCEPTION_PROLOG_COMMON_3(0x200) > > + addi r3,r1,STACK_FRAME_OVERHEAD > > + BRANCH_LINK_TO_FAR(machine_check_early) /* Function call > > ABI */ > > Is there any reason you can't use the existing > machine_check_powernv_early code to do all this? Code sharing is nice but if we envision this going to stable kernels butchering the existing handler is going to be a nightmare. The code is quite a bit different between kernel versions. This code as is requires the bit that introduces EXCEPTION_PROLOG_COMMON_1 and then should work on Linux 3.14+ Thanks Michal
