linux-kernel - [PATCH] perf bench: Add support for 32-bit systems with 64-bit time

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Date:   Thu,  9 Sep 2021 14:25:43 +1000
From:   Alistair Francis <alistair.francis@...nsource.wdc.com>
To:     linux-riscv@...ts.infradead.org, linux-perf-users@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, alistair23@...il.com,
        namhyung@...nel.org, jolsa@...hat.com,
        alexander.shishkin@...ux.intel.com, mark.rutland@....com,
        acme@...nel.org, dave@...olabs.net, dvhart@...radead.org,
        peterz@...radead.org, mingo@...hat.com, tglx@...utronix.de,
        atish.patra@....com, arnd@...db.de,
        Alistair Francis <alistair.francis@....com>
Subject: [PATCH] perf bench: Add support for 32-bit systems with 64-bit time_t

From: Alistair Francis <alistair.francis@....com>

Some 32-bit architectures (such are 32-bit RISC-V) only have a 64-bit
time_t and as such don't have the SYS_futex syscall. This patch will
allow us to use the SYS_futex_time64 syscall on those platforms.

This patch does not attempt to gracefully allow 32-bit architectures
with both SYS_futex and SYS_futex_time64 to support a 64-bit time_t.
This patch only applies to 32-bit architectures with a 64-bit time_t.

Signed-off-by: Alistair Francis <alistair.francis@....com>
---
 tools/perf/bench/futex.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/perf/bench/futex.h b/tools/perf/bench/futex.h
index b3853aac3021..912342d7f594 100644
--- a/tools/perf/bench/futex.h
+++ b/tools/perf/bench/futex.h
@@ -27,6 +27,17 @@ struct bench_futex_parameters {
 	unsigned int nrequeue;
 };
 
+/**
+ * Some newer 32-bit architectures (such as RISC-V 32-bit) don't have
+ * the SYS_futex syscall and instead only have the SYS_futex_time64 call.
+ * Let's ensure that those still compile and run by just using the
+ * SYS_futex_time64 syscall. On these systems `struct timespec` will use a
+ * 64-bit time_t so the SYS_futex_time64 call will work.
+ */
+#if !defined(SYS_futex) && defined(SYS_futex_time64)
+ #define SYS_futex SYS_futex_time64
+#endif
+
 /**
  * futex() - SYS_futex syscall wrapper
  * @uaddr:	address of first futex
-- 
2.31.1