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From 0f1e01960c3e082feac098be5b754ad3e06c820a Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@google.com>
Date: Tue, 13 Feb 2018 16:45:20 +0100
Subject: [PATCH 01/12] kaiser: fix compile error without vsyscall
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Tobias noticed a compile error on 4.4.115, and it's the same on 4.9.80:
arch/x86/mm/kaiser.c: In function ‘kaiser_init’:
arch/x86/mm/kaiser.c:348:8: error: ‘vsyscall_pgprot’ undeclared
(first use in this function)
It seems like his combination of kernel options doesn't work for KAISER.
X86_VSYSCALL_EMULATION is not set on his system, while LEGACY_VSYSCALL
is set to NONE (LEGACY_VSYSCALL_NONE=y). He managed to get things
compiling again, by moving the 'extern unsigned long vsyscall_pgprot'
outside of the preprocessor statement. This works because the optimizer
removes that code (vsyscall_enabled() is always false) - and that's how
it was done in some older backports.
Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/vsyscall.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/vsyscall.h b/arch/x86/include/asm/vsyscall.h
index 9ee8506..62210da 100644
--- a/arch/x86/include/asm/vsyscall.h
+++ b/arch/x86/include/asm/vsyscall.h
@@ -13,7 +13,6 @@ extern void map_vsyscall(void);
*/
extern bool emulate_vsyscall(struct pt_regs *regs, unsigned long address);
extern bool vsyscall_enabled(void);
-extern unsigned long vsyscall_pgprot;
#else
static inline void map_vsyscall(void) {}
static inline bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
@@ -22,5 +21,6 @@ static inline bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
}
static inline bool vsyscall_enabled(void) { return false; }
#endif
+extern unsigned long vsyscall_pgprot;
#endif /* _ASM_X86_VSYSCALL_H */
--
2.7.4
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