> On Oct 20, 2017, at 9:57 AM, Khalid Aziz <khalid.aziz@xxxxxxxxxx> wrote: > > Patch 9/10 > When a processor supports additional metadata on memory pages, that > additional metadata needs to be copied to new memory pages when those > pages are moved. This patch allows architecture specific code to > replace the default copy_highpage() routine with arch specific > version that copies the metadata as well besides the data on the page. > > Patch 10/10 > This patch adds support for a user space task to enable ADI and enable > tag checking for subsets of its address space. As part of enabling > this feature, this patch adds to support manipulation of precise > exception for memory corruption detection, adds code to save and > restore tags on page swap and migration, and adds code to handle ADI > tagged addresses for DMA. > > Changelog v9: > > - Patch 1/10: No changes > - Patch 2/10: No changes > - Patch 3/10: No changes > - Patch 4/10: No changes > - Patch 5/10: No changes > - Patch 6/10: No changes > - Patch 7/10: No changes > - Patch 8/10: No changes > - Patch 9/10: New patch > - Patch 10/10: Patch 9 from v8. Added code to copy ADI tags when > pages are migrated. Updated code to detect overflow and underflow > of addresses when allocating tag storage. Patch 09/10 wasn't delivered to me, but I reviewed the copy on lkml.org. The changes looks good, but there is one remaining functional issue which I've pointed out twice now in previous comments that still has not been addressed: The code paths through rtrap that overwrite PSTATE need to also set PSTATE.mcde=1 since additional kernel work done after PSTATE is overwritten could access ADI-enabled user memory and depend on version checking being enabled. For example, rtrap may call SCHEDULE_USER and resume execution in another thread. Without a fix, the resumed thread will run with PSTATE.mcde=0 until it completes a return to user mode or is rescheduled on a CPU where PSTATE.mcde is set. If the thread accesses ADI-enabled user memory with a versioned address (e.g. to complete some I/O) in that timeframe then the access will fail. Here is what you need to fix it: diff --git a/arch/sparc/kernel/rtrap_64.S b/arch/sparc/kernel/rtrap_64.S index dff86fa..07c82a7 100644 --- a/arch/sparc/kernel/rtrap_64.S +++ b/arch/sparc/kernel/rtrap_64.S @@ -24,13 +24,21 @@ .align 32 __handle_preemption: call SCHEDULE_USER - wrpr %g0, RTRAP_PSTATE, %pstate +661: wrpr %g0, RTRAP_PSTATE, %pstate + .section .sun_m7_1insn_patch, "ax" + .word 661b + wrpr %g0, RTRAP_PSTATE | PSTATE_MCDE, %pstate + .previous ba,pt %xcc, __handle_preemption_continue wrpr %g0, RTRAP_PSTATE_IRQOFF, %pstate __handle_user_windows: call fault_in_user_windows - wrpr %g0, RTRAP_PSTATE, %pstate +661: wrpr %g0, RTRAP_PSTATE, %pstate + .section .sun_m7_1insn_patch, "ax" + .word 661b + wrpr %g0, RTRAP_PSTATE | PSTATE_MCDE, %pstate + .previous ba,pt %xcc, __handle_preemption_continue wrpr %g0, RTRAP_PSTATE_IRQOFF, %pstate @@ -47,7 +55,11 @@ __handle_signal: add %sp, PTREGS_OFF, %o0 mov %l0, %o2 call do_notify_resume - wrpr %g0, RTRAP_PSTATE, %pstate +661: wrpr %g0, RTRAP_PSTATE, %pstate + .section .sun_m7_1insn_patch, "ax" + .word 661b + wrpr %g0, RTRAP_PSTATE | PSTATE_MCDE, %pstate + .previous wrpr %g0, RTRAP_PSTATE_IRQOFF, %pstate /* Signal delivery can modify pt_regs tstate, so we must diff --git a/arch/sparc/kernel/urtt_fill.S b/arch/sparc/kernel/urtt_fill.S index 364af32..3a7f2d8 100644 --- a/arch/sparc/kernel/urtt_fill.S +++ b/arch/sparc/kernel/urtt_fill.S @@ -49,7 +49,11 @@ user_rtt_fill_fixup_common: SET_GL(0) .previous - wrpr %g0, RTRAP_PSTATE, %pstate +661: wrpr %g0, RTRAP_PSTATE, %pstate + .section .sun_m7_1insn_patch, "ax" + .word 661b + wrpr %g0, RTRAP_PSTATE | PSTATE_MCDE, %pstate + .previous mov %l1, %g6 ldx [%g6 + TI_TASK], %g4
