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Date: Thu, 28 Jul 2016 02:59:45 +0000 (UTC)
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Boqun Feng <boqun.feng@...il.com>
Cc: linux-kernel@...r.kernel.org,
linux-api <linux-api@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Russell King <linux@....linux.org.uk>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Paul Turner <pjt@...gle.com>,
Andrew Hunter <ahh@...gle.com>,
Peter Zijlstra <peterz@...radead.org>,
Andy Lutomirski <luto@...capital.net>,
Andi Kleen <andi@...stfloor.org>,
Dave Watson <davejwatson@...com>, Chris Lameter <cl@...ux.com>,
Ben Maurer <bmaurer@...com>, rostedt <rostedt@...dmis.org>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Josh Triplett <josh@...htriplett.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>
Subject: Re: [RFC 4/4] Restartable sequences: Add self-tests for PPC
----- On Jul 27, 2016, at 11:05 AM, Boqun Feng boqun.feng@...il.com wrote:
> As rseq syscall is enabled on PPC, implement the self-tests on PPC to
> verify the implementation of the syscall.
>
> Please note we only support 32bit userspace on BE kernel.
>
> Signed-off-by: Boqun Feng <boqun.feng@...il.com>
> ---
> tools/testing/selftests/rseq/param_test.c | 14 ++++
> tools/testing/selftests/rseq/rseq.h | 120 ++++++++++++++++++++++++++++++
> 2 files changed, 134 insertions(+)
>
> diff --git a/tools/testing/selftests/rseq/param_test.c
> b/tools/testing/selftests/rseq/param_test.c
> index db25e0a818e5..e2cb1b165f81 100644
> --- a/tools/testing/selftests/rseq/param_test.c
> +++ b/tools/testing/selftests/rseq/param_test.c
> @@ -75,6 +75,20 @@ static __thread unsigned int yield_mod_cnt, nr_retry;
> "bne 222b\n\t" \
> "333:\n\t"
>
> +#elif __PPC__
> +#define INJECT_ASM_REG "r18"
> +
> +#define RSEQ_INJECT_CLOBBER \
> + , INJECT_ASM_REG
> +
> +#define RSEQ_INJECT_ASM(n) \
> + "lwz %%" INJECT_ASM_REG ", %[loop_cnt_" #n "]\n\t" \
> + "cmpwi %%" INJECT_ASM_REG ", 0\n\t" \
> + "beq 333f\n\t" \
> + "222:\n\t" \
> + "subic. %%" INJECT_ASM_REG ", %%" INJECT_ASM_REG ", 1\n\t" \
> + "bne 222b\n\t" \
> + "333:\n\t"
> #else
> #error unsupported target
> #endif
> diff --git a/tools/testing/selftests/rseq/rseq.h
> b/tools/testing/selftests/rseq/rseq.h
> index 791e14cf42ae..dea0bea52566 100644
> --- a/tools/testing/selftests/rseq/rseq.h
> +++ b/tools/testing/selftests/rseq/rseq.h
> @@ -138,6 +138,35 @@ do { \
> #define has_fast_acquire_release() 0
> #define has_single_copy_load_64() 1
>
> +#elif __PPC__
> +#define smp_mb() __asm__ __volatile__ ("sync" : : : "memory")
> +#define smp_lwsync() __asm__ __volatile__ ("lwsync" : : : "memory")
> +#define smp_rmb() smp_lwsync()
> +#define smp_wmb() smp_lwsync()
> +
> +#define smp_load_acquire(p) \
> +__extension__ ({ \
> + __typeof(*p) ____p1 = READ_ONCE(*p); \
> + smp_lwsync(); \
> + ____p1; \
> +})
> +
> +#define smp_acquire__after_ctrl_dep() smp_lwsync()
> +
> +#define smp_store_release(p, v) \
> +do { \
> + smp_lwsync(); \
> + WRITE_ONCE(*p, v); \
> +} while (0)
> +
> +#define has_fast_acquire_release() 1
Can you check if defining has_fast_acquire_release() to 0 speeds up
performance significantly ? It turns the smp_lwsync() into a
compiler barrier() on the smp_load_acquire() side (fast-path), and
turn the smp_lwsync() into a membarrier system call instead of the
matching smp_store_release() (slow path).
Thanks,
Mathieu
> +
> +# if __PPC64__
> +# define has_single_copy_load_64() 1
> +# else
> +# define has_single_copy_load_64() 0
> +# endif
> +
> #else
> #error unsupported target
> #endif
> @@ -404,6 +433,97 @@ bool rseq_finish(struct rseq_lock *rlock,
> : succeed
> );
> }
> +#elif __PPC64__
> + {
> + /*
> + * The __rseq_table section can be used by debuggers to better
> + * handle single-stepping through the restartable critical
> + * sections.
> + */
> + __asm__ __volatile__ goto (
> + ".pushsection __rseq_table, \"aw\"\n\t"
> + ".balign 8\n\t"
> + "4:\n\t"
> + ".quad 1f, 2f, 3f\n\t"
> + ".popsection\n\t"
> + "1:\n\t"
> + RSEQ_INJECT_ASM(1)
> + "lis %%r17, (4b)@highest\n\t"
> + "ori %%r17, %%r17, (4b)@higher\n\t"
> + "rldicr %%r17, %%r17, 32, 31\n\t"
> + "oris %%r17, %%r17, (4b)@h\n\t"
> + "ori %%r17, %%r17, (4b)@l\n\t"
> + "std %%r17, 0(%[rseq_cs])\n\t"
> + RSEQ_INJECT_ASM(2)
> + "lwz %%r17, %[current_event_counter]\n\t"
> + "li %%r16, 0\n\t"
> + "cmpw cr7, %[start_event_counter], %%r17\n\t"
> + "bne cr7, 3f\n\t"
> + RSEQ_INJECT_ASM(3)
> + "std %[to_write], 0(%[target])\n\t"
> + "2:\n\t"
> + RSEQ_INJECT_ASM(4)
> + "std %%r16, 0(%[rseq_cs])\n\t"
> + "b %l[succeed]\n\t"
> + "3:\n\t"
> + "li %%r16, 0\n\t"
> + "std %%r16, 0(%[rseq_cs])\n\t"
> + : /* no outputs */
> + : [start_event_counter]"r"(start_value.event_counter),
> + [current_event_counter]"m"(start_value.rseqp->abi.u.e.event_counter),
> + [to_write]"r"(to_write),
> + [target]"b"(p),
> + [rseq_cs]"b"(&start_value.rseqp->abi.rseq_cs)
> + RSEQ_INJECT_INPUT
> + : "r16", "r17", "memory", "cc"
> + RSEQ_INJECT_CLOBBER
> + : succeed
> + );
> + }
> +#elif __PPC__
> + {
> + /*
> + * The __rseq_table section can be used by debuggers to better
> + * handle single-stepping through the restartable critical
> + * sections.
> + */
> + __asm__ __volatile__ goto (
> + ".pushsection __rseq_table, \"aw\"\n\t"
> + ".balign 8\n\t"
> + "4:\n\t"
> + ".long 0x0, 1f, 0x0, 2f, 0x0, 3f\n\t" /* 32 bit only supported on BE */
> + ".popsection\n\t"
> + "1:\n\t"
> + RSEQ_INJECT_ASM(1)
> + "lis %%r17, (4b)@ha\n\t"
> + "addi %%r17, %%r17, (4b)@l\n\t"
> + "stw %%r17, 0(%[rseq_cs])\n\t"
> + RSEQ_INJECT_ASM(2)
> + "lwz %%r17, %[current_event_counter]\n\t"
> + "li %%r16, 0\n\t"
> + "cmpw cr7, %[start_event_counter], %%r17\n\t"
> + "bne cr7, 3f\n\t"
> + RSEQ_INJECT_ASM(3)
> + "stw %[to_write], 0(%[target])\n\t"
> + "2:\n\t"
> + RSEQ_INJECT_ASM(4)
> + "stw %%r16, 0(%[rseq_cs])\n\t"
> + "b %l[succeed]\n\t"
> + "3:\n\t"
> + "li %%r16, 0\n\t"
> + "stw %%r16, 0(%[rseq_cs])\n\t"
> + : /* no outputs */
> + : [start_event_counter]"r"(start_value.event_counter),
> + [current_event_counter]"m"(start_value.rseqp->abi.u.e.event_counter),
> + [to_write]"r"(to_write),
> + [target]"b"(p),
> + [rseq_cs]"b"(&start_value.rseqp->abi.rseq_cs)
> + RSEQ_INJECT_INPUT
> + : "r16", "r17", "memory", "cc"
> + RSEQ_INJECT_CLOBBER
> + : succeed
> + );
> + }
> #else
> #error unsupported target
> #endif
> --
> 2.9.0
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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