linux-kernel - [PATCH 2/2] arm_sdei: remove the set_fs calls in sdei_event

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Date:   Tue, 14 Apr 2020 16:23:02 +0200
From:   Christoph Hellwig <hch@....de>
To:     James Morse <james.morse@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] arm_sdei: remove the set_fs calls in sdei_event_handler

There are only two callbacks that can be called, which both
eventually end up calling __ghes_sdei_callback.

__ghes_sdei_callback calls irq_work_queue which is a normal
kernel helper called from all kinds of contexts and
ghes_in_nmi_queue_one_entry.  ghes_in_nmi_queue_one_entry is
also called from other code without messing with the address
limit, so it better work without it.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 drivers/firmware/arm_sdei.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index bdd6461647d7..1c51b378dfca 100644
--- a/drivers/firmware/arm_sdei.c
+++ b/drivers/firmware/arm_sdei.c
@@ -1137,19 +1137,12 @@ int sdei_event_handler(struct pt_regs *regs,
 		       struct sdei_registered_event *arg)
 {
 	int err;
-	mm_segment_t orig_addr_limit;
 	u32 event_num = arg->event_num;
 
-	orig_addr_limit = get_fs();
-	set_fs(USER_DS);
-
 	err = arg->callback(event_num, regs, arg->callback_arg);
 	if (err)
 		pr_err_ratelimited("event %u on CPU %u failed with error: %d\n",
 				   event_num, smp_processor_id(), err);
-
-	set_fs(orig_addr_limit);
-
 	return err;
 }
 NOKPROBE_SYMBOL(sdei_event_handler);
-- 
2.25.1