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* [PATCH] arm64: kvm: fix gcc-10 shift warning
@ 2020-04-29 18:56 ` Arnd Bergmann
  0 siblings, 0 replies; 21+ messages in thread
From: Arnd Bergmann @ 2020-04-29 18:56 UTC (permalink / raw)
  To: Marc Zyngier, Mike Rapoport, Andrew Morton
  Cc: Arnd Bergmann, Benjamin Herrenschmidt, Brian Cain,
	Catalin Marinas, Christophe Leroy, Fenghua Yu,
	Geert Uytterhoeven, Guan Xuetao, James Morse, Jonas Bonn,
	Julien Thierry, Ley Foon Tan, Michael Ellerman, Paul Mackerras,
	Rich Felker, Russell King, Stafford Horne, Stefan Kristiansson,
	Suzuki K Poulose, Tony Luck, Will Deacon, Yoshinori Sato,
	Stephen Rothwell, Paolo Bonzini, linux-arm-kernel, kvmarm,
	linux-kernel

gcc-10 warns that the 32-bit zero cannot be shifted more than
32 bits to the right:

arch/arm64/kvm/../../../virt/kvm/arm/mmu.c: In function 'clear_hyp_p4d_entry':
arch/arm64/include/asm/pgtable.h:630:35: error: right shift count >= width of type [-Werror=shift-count-overflow]
  630 | #define pud_index(addr)  (((addr) >> PUD_SHIFT) & (PTRS_PER_PUD - 1))
      |                                   ^~
arch/arm64/include/asm/memory.h:271:45: note: in definition of macro '__phys_to_virt'
  271 | #define __phys_to_virt(x) ((unsigned long)((x) - physvirt_offset))
      |                                             ^
arch/arm64/include/asm/pgtable.h:633:42: note: in expansion of macro '__va'
  633 | #define pud_offset(dir, addr)  ((pud_t *)__va(pud_offset_phys((dir), (addr))))
      |                                          ^~~~
arch/arm64/include/asm/pgtable.h:632:73: note: in expansion of macro 'pud_index'
  632 | #define pud_offset_phys(dir, addr) (p4d_page_paddr(READ_ONCE(*(dir))) + pud_index(addr) * sizeof(pud_t))
      |                                                                         ^~~~~~~~~
arch/arm64/include/asm/pgtable.h:633:47: note: in expansion of macro 'pud_offset_phys'
  633 | #define pud_offset(dir, addr)  ((pud_t *)__va(pud_offset_phys((dir), (addr))))
      |                                               ^~~~~~~~~~~~~~~
arch/arm64/kvm/../../../virt/kvm/arm/mmu.c:510:36: note: in expansion of macro 'pud_offset'
  510 |  pud_t *pud_table __maybe_unused = pud_offset(p4d, 0);
      |                                    ^~~~~~~~~~

This is harmless, and the warning is a little bit silly for
a zero constant, but it's trivial to fix by making it an
unsigned long, so do that.

Fixes: 22998131ab33 ("arm64: add support for folded p4d page tables")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 virt/kvm/arm/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 48d4288c5f1b..534d9798c3cb 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -507,7 +507,7 @@ static void clear_hyp_pgd_entry(pgd_t *pgd)
 
 static void clear_hyp_p4d_entry(p4d_t *p4d)
 {
-	pud_t *pud_table __maybe_unused = pud_offset(p4d, 0);
+	pud_t *pud_table __maybe_unused = pud_offset(p4d, 0UL);
 	VM_BUG_ON(p4d_huge(*p4d));
 	p4d_clear(p4d);
 	pud_free(NULL, pud_table);
-- 
2.26.0


^ permalink raw reply related	[flat|nested] 21+ messages in thread

end of thread, other threads:[~2020-04-30  9:50 UTC | newest]

Thread overview: 21+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-04-29 18:56 [PATCH] arm64: kvm: fix gcc-10 shift warning Arnd Bergmann
2020-04-29 18:56 ` Arnd Bergmann
2020-04-29 18:56 ` Arnd Bergmann
2020-04-29 21:09 ` Will Deacon
2020-04-29 21:09   ` Will Deacon
2020-04-29 21:09   ` Will Deacon
2020-04-29 22:42 ` Stephen Rothwell
2020-04-29 22:42   ` Stephen Rothwell
2020-04-29 22:42   ` Stephen Rothwell
2020-04-30  8:02 ` Marc Zyngier
2020-04-30  8:02   ` Marc Zyngier
2020-04-30  8:02   ` Marc Zyngier
2020-04-30  8:29   ` Will Deacon
2020-04-30  8:29     ` Will Deacon
2020-04-30  8:29     ` Will Deacon
2020-04-30  9:39     ` Stephen Rothwell
2020-04-30  9:39       ` Stephen Rothwell
2020-04-30  9:39       ` Stephen Rothwell
2020-04-30  9:50       ` Will Deacon
2020-04-30  9:50         ` Will Deacon
2020-04-30  9:50         ` Will Deacon

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