[PATCH 0/3] firmare: arm_sdei: Extras for v5.8

[PATCH 0/3] firmare: arm_sdei: Extras for v5.8

[James Morse]

Hi Will, Catalin,

Some extra patches for SDEI if you're still willing to add to your tree.

Hanjun's patch to cleanup some ACPI table handling conflicts with
Sudeep's patch that you already have queued.

Based on arm64's for-next/sdei branch: v5.7-rc3-1-gcaf2cd610dbb

For the tag, I'd describe all four patches as:
---
Cleanup the driver probing, remove some unused module exports and document
the reason behind a set_fs() call.
---


Thanks,

James


Christoph Hellwig (1):
  firmware: arm_sdei: remove unused interfaces

Hanjun Guo (1):
  firmware: arm_sdei: Put the SDEI table after using it

James Morse (1):
  firmware: arm_sdei: Document the motivation behind these set_fs()
    calls

 drivers/firmware/arm_sdei.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

-- 
2.19.1


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[PATCH 1/3] firmware: arm_sdei: Put the SDEI table after using it

[James Morse]

From: Hanjun Guo <guohanjun@huawei.com>

The acpi_get_table() should be coupled with acpi_put_table() if
the mapped table is not used for runtime after the initialization
to release the table mapping, put the SDEI table after using it.

Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Link: https://lore.kernel.org/linux-arm-kernel/1589021566-46373-1-git-send-email-guohanjun@huawei.com/
Signed-off-by: James Morse <james.morse@arm.com>
---
 drivers/firmware/arm_sdei.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index 5afd7409e6fa..a33b701ab2b0 100644
--- a/drivers/firmware/arm_sdei.c
+++ b/drivers/firmware/arm_sdei.c
@@ -1096,6 +1096,8 @@ static bool __init sdei_present_acpi(void)
 	if (ACPI_FAILURE(status))
 		return false;
 
+	acpi_put_table(sdei_table_header);
+
 	return true;
 }
 
-- 
2.19.1


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[PATCH 2/3] firmware: arm_sdei: remove unused interfaces

[James Morse]

From: Christoph Hellwig <hch@lst.de>

The export symbols to register/unregister and enable/disable events
aren't used upstream, remove them.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/linux-arm-kernel/20200504164224.2842960-1-hch@lst.de/
[ dropped the parts of Christoph's patch that made the API static too ]
Signed-off-by: James Morse <james.morse@arm.com>
---
 drivers/firmware/arm_sdei.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index a33b701ab2b0..b12b99a19f66 100644
--- a/drivers/firmware/arm_sdei.c
+++ b/drivers/firmware/arm_sdei.c
@@ -429,7 +429,6 @@ int sdei_event_enable(u32 event_num)
 
 	return err;
 }
-EXPORT_SYMBOL(sdei_event_enable);
 
 static int sdei_api_event_disable(u32 event_num)
 {
@@ -471,7 +470,6 @@ int sdei_event_disable(u32 event_num)
 
 	return err;
 }
-EXPORT_SYMBOL(sdei_event_disable);
 
 static int sdei_api_event_unregister(u32 event_num)
 {
@@ -533,7 +531,6 @@ int sdei_event_unregister(u32 event_num)
 
 	return err;
 }
-EXPORT_SYMBOL(sdei_event_unregister);
 
 /*
  * unregister events, but don't destroy them as they are re-registered by
@@ -643,7 +640,6 @@ int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg)
 
 	return err;
 }
-EXPORT_SYMBOL(sdei_event_register);
 
 static int sdei_reregister_event_llocked(struct sdei_event *event)
 {
-- 
2.19.1


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[PATCH 3/3] firmware: arm_sdei: Document the motivation behind these set_fs() calls

[James Morse]

The SDEI handler save/restores the addr_limit using set_fs(). It isn't
very clear why. The reason is to mirror the arch code's entry assembly.
The arch code does this because perf may access user-space, and
inheriting the addr_limit may be a problem.

Add a comment explaining why this is here.

Link: https://bugs.chromium.org/p/project-zero/issues/detail?id=822
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Morse <james.morse@arm.com>
---
 drivers/firmware/arm_sdei.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index b12b99a19f66..e7e36aab2386 100644
--- a/drivers/firmware/arm_sdei.c
+++ b/drivers/firmware/arm_sdei.c
@@ -1128,6 +1128,14 @@ int sdei_event_handler(struct pt_regs *regs,
 	mm_segment_t orig_addr_limit;
 	u32 event_num = arg->event_num;
 
+	/*
+	 * Save restore 'fs'.
+	 * The architecture's entry code save/restores 'fs' when taking an
+	 * exception from the kernel. This ensures addr_limit isn't inherited
+	 * if you interrupted something that allowed the uaccess routines to
+	 * access kernel memory.
+	 * Do the same here because this doesn't come via the same entry code.
+	*/
 	orig_addr_limit = get_fs();
 	set_fs(USER_DS);
 
-- 
2.19.1


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Re: [PATCH 0/3] firmare: arm_sdei: Extras for v5.8

[Will Deacon]

On Tue, 19 May 2020 19:21:05 +0100, James Morse wrote:
> Some extra patches for SDEI if you're still willing to add to your tree.
> 
> Hanjun's patch to cleanup some ACPI table handling conflicts with
> Sudeep's patch that you already have queued.
> 
> Based on arm64's for-next/sdei branch: v5.7-rc3-1-gcaf2cd610dbb
> 
> [...]

Applied to arm64 (for-next/sdei), thanks!

[1/3] firmware: arm_sdei: Put the SDEI table after using it
      https://git.kernel.org/arm64/c/70e6352aefb1
[2/3] firmware: arm_sdei: remove unused interfaces
      https://git.kernel.org/arm64/c/82b2077afccd
[3/3] firmware: arm_sdei: Document the motivation behind these set_fs() calls
      https://git.kernel.org/arm64/c/472de63b0b83

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev

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