linux-kernel - [PATCH 4.19 72/74] gcc-9: properly declare the {pv,hv}clock

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Message-Id: <20190805124941.618238077@linuxfoundation.org>
Date:   Mon,  5 Aug 2019 15:03:25 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.19 72/74] gcc-9: properly declare the {pv,hv}clock_page storage

From: Linus Torvalds <torvalds@...ux-foundation.org>

commit 459e3a21535ae3c7a9a123650e54f5c882b8fcbf upstream.

The pvlock_page and hvclock_page variables are (as the name implies)
addresses to pages, created by the linker script.

But we declared them as just "extern u8" variables, which _works_, but
now that gcc does some more bounds checking, it causes warnings like

    warning: array subscript 1 is outside array bounds of ‘u8[1]’

when we then access more than one byte from those variables.

Fix this by simply making the declaration of the variables match
reality, which makes the compiler happy too.

Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/entry/vdso/vclock_gettime.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -29,12 +29,12 @@ extern int __vdso_gettimeofday(struct ti
 extern time_t __vdso_time(time_t *t);
 
 #ifdef CONFIG_PARAVIRT_CLOCK
-extern u8 pvclock_page
+extern u8 pvclock_page[PAGE_SIZE]
 	__attribute__((visibility("hidden")));
 #endif
 
 #ifdef CONFIG_HYPERV_TSCPAGE
-extern u8 hvclock_page
+extern u8 hvclock_page[PAGE_SIZE]
 	__attribute__((visibility("hidden")));
 #endif