Re: [PATCH][RFA/RFC] Stack clash mitigation patch 05/08

2017-07-31 Thread Jeff Law
On 07/21/2017 02:25 PM, Segher Boessenkool wrote: > On Thu, Jul 20, 2017 at 08:20:52AM -0600, Jeff Law wrote: >>> Can only combine-stack-adjustments do this? It seems like something >>> many passes could do, and then your new note doesn't help. >> SO far it's only been observed with c-s-a, but fur

[PATCH][RFA/RFC] Stack clash mitigation patch 05/08 - V3

2017-07-30 Thread Jeff Law
This patch catches a couple places where the generic parts of the compiler would transform prologue probing sequences in unsafe ways. Changes since V2: Testing for aarch64 showed the scheduler would perform transformations similar to combine-stack-adjustments via its dependency breaking transfor

Re: [PATCH][RFA/RFC] Stack clash mitigation patch 05/08

2017-07-21 Thread Segher Boessenkool
On Thu, Jul 20, 2017 at 08:20:52AM -0600, Jeff Law wrote: > > Can only combine-stack-adjustments do this? It seems like something > > many passes could do, and then your new note doesn't help. > SO far it's only been observed with c-s-a, but further auditing is > certainly desirable here, particul

Re: [PATCH][RFA/RFC] Stack clash mitigation patch 05/08

2017-07-20 Thread Jeff Law
On 07/20/2017 07:09 AM, Segher Boessenkool wrote: > Hi Jeff, > > On Tue, Jul 18, 2017 at 11:17:48PM -0600, Jeff Law wrote: >> It turns out combine-stack-adjustments would take >> >> allocate PROBE_INTERVAL >> probe >> allocate PROBE_INTERVAL >> probe >> allocate PROBE_INTERVAL >> probe >> allocate

Re: [PATCH][RFA/RFC] Stack clash mitigation patch 05/08

2017-07-20 Thread Segher Boessenkool
Hi Jeff, On Tue, Jul 18, 2017 at 11:17:48PM -0600, Jeff Law wrote: > It turns out combine-stack-adjustments would take > > allocate PROBE_INTERVAL > probe > allocate PROBE_INTERVAL > probe > allocate PROBE_INTERVAL > probe > allocate RESIDUAL > > And turn that into > > allocate (3 * PROBE_INTER

[PATCH][RFA/RFC] Stack clash mitigation patch 05/08

2017-07-18 Thread Jeff Law
I don't think this has changed in any significant way since V1. -- The prior patch introduced -fstack-clash-protection prologues for the x86. And yet we still saw large allocations in our testing. It turns out combine-stack-adjustments would take allocate PROBE_INTERVAL probe allocate PROBE_I

[PATCH][RFA/RFC] Stack clash mitigation patch 05/08

2017-07-11 Thread Jeff Law
The prior patch introduced -fstack-check=clash prologues for the x86. And yet we still saw large allocations in our testing. It turns out combine-stack-adjustments would take allocate PROBE_INTERVAL probe allocate PROBE_INTERVAL probe allocate PROBE_INTERVAL probe allocate RESIDUAL And turn tha