linux-kernel - [PATCH 5.18 0071/1095] RISC-V: Update user page mapping only once during start

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Message-Id: <20220815180432.452222140@linuxfoundation.org>
Date:   Mon, 15 Aug 2022 19:51:10 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Anup Patel <anup@...infault.org>,
        Atish Patra <atishp@...osinc.com>, Guo Ren <guoren@...nel.org>,
        Palmer Dabbelt <palmer@...osinc.com>
Subject: [PATCH 5.18 0071/1095] RISC-V: Update user page mapping only once during start

From: Atish Patra <atishp@...osinc.com>

commit 133a6d1fe7d7ad8393af025c4dde379c0616661f upstream.

Currently, riscv_pmu_event_set_period updates the userpage mapping.
However, the caller of riscv_pmu_event_set_period should update
the userpage mapping because the counter can not be updated/started
from set_period function in counter overflow path.

Invoke the perf_event_update_userpage at the caller so that it
doesn't get invoked twice during counter start path.

Fixes: f5bfa23f576f ("RISC-V: Add a perf core library for pmu drivers")
Reviewed-by: Anup Patel <anup@...infault.org>
Signed-off-by: Atish Patra <atishp@...osinc.com>
Reviewed-by: Guo Ren <guoren@...nel.org>
Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/r/20220711174632.4186047-3-atishp@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/perf/riscv_pmu.c     |    1 -
 drivers/perf/riscv_pmu_sbi.c |    1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/perf/riscv_pmu.c
+++ b/drivers/perf/riscv_pmu.c
@@ -170,7 +170,6 @@ int riscv_pmu_event_set_period(struct pe
 		left = (max_period >> 1);
 
 	local64_set(&hwc->prev_count, (u64)-left);
-	perf_event_update_userpage(event);
 
 	return overflow;
 }
--- a/drivers/perf/riscv_pmu_sbi.c
+++ b/drivers/perf/riscv_pmu_sbi.c
@@ -542,6 +542,7 @@ static inline void pmu_sbi_start_overflo
 			sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, idx, 1,
 				  flag, init_val, 0, 0);
 #endif
+			perf_event_update_userpage(event);
 		}
 		ctr_ovf_mask = ctr_ovf_mask >> 1;
 		idx++;