Re: [PATCH] RISC-V: Break load reservations during switch_to

2019-06-07 Thread Palmer Dabbelt
On Thu, 06 Jun 2019 12:32:01 PDT (-0700), sch...@linux-m68k.org wrote: On Jun 06 2019, Christoph Hellwig wrote: On Wed, Jun 05, 2019 at 04:17:35PM -0700, Palmer Dabbelt wrote: REG_S ra, TASK_THREAD_RA_RA(a3) + /* +* The Linux ABI allows programs to depend on load reserv

Re: [PATCH] RISC-V: Break load reservations during switch_to

2019-06-06 Thread Andreas Schwab
On Jun 06 2019, Christoph Hellwig wrote: > On Wed, Jun 05, 2019 at 04:17:35PM -0700, Palmer Dabbelt wrote: >> REG_S ra, TASK_THREAD_RA_RA(a3) >> +/* >> + * The Linux ABI allows programs to depend on load reservations being >> + * broken on context switches, but the ISA doesn't r

Re: [PATCH] RISC-V: Break load reservations during switch_to

2019-06-06 Thread Palmer Dabbelt
On Thu, 06 Jun 2019 02:05:18 PDT (-0700), Christoph Hellwig wrote: On Wed, Jun 05, 2019 at 04:17:35PM -0700, Palmer Dabbelt wrote: REG_S ra, TASK_THREAD_RA_RA(a3) + /* +* The Linux ABI allows programs to depend on load reservations being +* broken on context switch

Re: [PATCH] RISC-V: Break load reservations during switch_to

2019-06-06 Thread Christoph Hellwig
On Wed, Jun 05, 2019 at 04:17:35PM -0700, Palmer Dabbelt wrote: > REG_S ra, TASK_THREAD_RA_RA(a3) > + /* > + * The Linux ABI allows programs to depend on load reservations being > + * broken on context switches, but the ISA doesn't require that the > + * hardware ever brea

Re: [PATCH] RISC-V: Break load reservations during switch_to

2019-06-06 Thread Marco Peereboom
Ah that’s sneaky!! > On Jun 6, 2019, at 12:17 AM, Palmer Dabbelt wrote: > > The comment describes why in detail. This was found because QEMU never > gives up load reservations, the issue is unlikely to manifest on real > hardware. > > Thanks to Carlos Eduardo for finding the bug! > > Signed-o