linux-kernel - [PATCH 05/20] efi/x86: avoid redundant cast of EFI firmware service pointer

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Date:   Fri,  3 Jan 2020 12:39:38 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Matthew Garrett <mjg59@...gle.com>
Subject: [PATCH 05/20] efi/x86: avoid redundant cast of EFI firmware service pointer

All EFI firmware call prototypes have been annotated as __efiapi,
permitting us to attach attributes regarding the calling convention
by overriding __efiapi to an architecture specific value.

On 32-bit x86, EFI firmware calls use the plain calling convention
where all arguments are passed via the stack, and cleaned up by the
caller. Let's add this to the __efiapi definition so we no longer
need to cast the function pointers before invoking them.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/x86/include/asm/efi.h | 8 +-------
 include/linux/efi.h        | 4 +++-
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index b35b5d423e9d..09c3fc468793 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -51,13 +51,7 @@ extern asmlinkage unsigned long efi_call_phys(void *, ...);
 })
 
 
-/*
- * Wrap all the virtual calls in a way that forces the parameters on the stack.
- */
-#define arch_efi_call_virt(p, f, args...)				\
-({									\
-	((efi_##f##_t __attribute__((regparm(0)))*) p->f)(args);	\
-})
+#define arch_efi_call_virt(p, f, args...)	p->f(args)
 
 #define efi_ioremap(addr, size, type, attr)	ioremap_cache(addr, size)
 
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 726673e98990..952c1659dfd9 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -48,8 +48,10 @@ typedef u16 efi_char16_t;		/* UNICODE character */
 typedef u64 efi_physical_addr_t;
 typedef void *efi_handle_t;
 
-#ifdef CONFIG_X86_64
+#if defined(CONFIG_X86_64)
 #define __efiapi __attribute__((ms_abi))
+#elif defined(CONFIG_X86_32)
+#define __efiapi __attribute__((regparm(0)))
 #else
 #define __efiapi
 #endif
-- 
2.20.1