linux-kernel - [tip:efi/core] efi/runtime-wrappers: Add {__,}efi_call

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Message-ID: <tip-f51c35f291062df14a3e9cc5779e417fe662e50e@git.kernel.org>
Date:	Thu, 28 Apr 2016 03:42:33 -0700
From:	tip-bot for Mark Rutland <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	ard.biesheuvel@...aro.org, linux@....linux.org.uk,
	peterz@...radead.org, will.deacon@....com,
	matt@...eblueprint.co.uk, bp@...en8.de,
	linux-kernel@...r.kernel.org, mark.rutland@....com,
	mingo@...nel.org, leif.lindholm@...aro.org,
	catalin.marinas@....com, tglx@...utronix.de, hpa@...or.com
Subject: [tip:efi/core] efi/runtime-wrappers: Add {__,}efi_call_virt()
 templates

Commit-ID:  f51c35f291062df14a3e9cc5779e417fe662e50e
Gitweb:     http://git.kernel.org/tip/f51c35f291062df14a3e9cc5779e417fe662e50e
Author:     Mark Rutland <mark.rutland@....com>
AuthorDate: Mon, 25 Apr 2016 21:07:03 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 28 Apr 2016 11:34:06 +0200

efi/runtime-wrappers: Add {__,}efi_call_virt() templates

Currently each architecture must implement two macros, efi_call_virt() and
__efi_call_virt(), which only differ by the presence or absence of a
return type. Otherwise, the logic surrounding the call is identical.

As each architecture must define the entire body of each, we can't place
any generic manipulation (e.g. irq flag validation) in the middle.

This patch adds template implementations of these macros. With these,
arch code can implement three template macros, avoiding reptition for
the void/non-void return cases:

* arch_efi_call_virt_setup()

  Sets up the environment for the call (e.g. switching page tables,
  allowing kernel-mode use of floating point, if required).

* arch_efi_call_virt()

  Performs the call. The last expression in the macro must be the call
  itself, allowing the logic to be shared by the void and non-void
  cases.

* arch_efi_call_virt_teardown()

  Restores the usual kernel environment once the call has returned.

While the savings from repition are minimal, we additionally gain the
ability to add common code around the call with the call environment set
up. This can be used to detect common firmware issues (e.g. bad irq mask
management).

Signed-off-by: Mark Rutland <mark.rutland@....com>
Signed-off-by: Matt Fleming <matt@...eblueprint.co.uk>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Leif Lindholm <leif.lindholm@...aro.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Russell King <linux@....linux.org.uk>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Will Deacon <will.deacon@....com>
Cc: linux-efi@...r.kernel.org
Link: http://lkml.kernel.org/r/1461614832-17633-32-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 drivers/firmware/efi/runtime-wrappers.c | 40 +++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index de69530..0677577 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -21,6 +21,46 @@
 #include <asm/efi.h>
 
 /*
+ * Arch code can implement the following three template macros, avoiding
+ * reptition for the void/non-void return cases of {__,}efi_call_virt:
+ *
+ *  * arch_efi_call_virt_setup
+ *
+ *    Sets up the environment for the call (e.g. switching page tables,
+ *    allowing kernel-mode use of floating point, if required).
+ *
+ *  * arch_efi_call_virt
+ *
+ *    Performs the call. The last expression in the macro must be the call
+ *    itself, allowing the logic to be shared by the void and non-void
+ *    cases.
+ *
+ *  * arch_efi_call_virt_teardown
+ *
+ *    Restores the usual kernel environment once the call has returned.
+ */
+
+#ifndef efi_call_virt
+#define efi_call_virt(f, args...)					\
+({									\
+	efi_status_t __s;						\
+	arch_efi_call_virt_setup();					\
+	__s = arch_efi_call_virt(f, args);				\
+	arch_efi_call_virt_teardown();					\
+	__s;								\
+})
+#endif
+
+#ifndef __efi_call_virt
+#define __efi_call_virt(f, args...)					\
+({									\
+	arch_efi_call_virt_setup();					\
+	arch_efi_call_virt(f, args);					\
+	arch_efi_call_virt_teardown();					\
+})
+#endif
+
+/*
  * According to section 7.1 of the UEFI spec, Runtime Services are not fully
  * reentrant, and there are particular combinations of calls that need to be
  * serialized. (source: UEFI Specification v2.4A)