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mips: vdso: Fix __arch_get_hw_counter() 

On some MIPS variants (e.g. MIPS r1), vDSO clock_mode is set to
VDSO_CLOCK_NONE.

When VDSO_CLOCK_NONE is set the expected kernel behavior is to fallback
on syscalls. To do that the generic vDSO library expects UULONG_MAX as
return value of __arch_get_hw_counter().

Fix __arch_get_hw_counter() on MIPS defining a __VDSO_USE_SYSCALL case
that addressed the described scenario.

Reported-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Tested-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: linux-mips@vger.kernel.org
This commit is contained in:
Vincenzo Frascino 2019-10-16 14:40:24 +01:00 committed by Paul Burton
parent 0ad8f7aa9f
commit 8a1bef4193
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GPG Key ID: 3EA79FACB57500DD
1 changed files with 3 additions and 1 deletions
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4
arch/mips/include/asm/vdso/gettimeofday.h
View File

@ -24,6 +24,8 @@
#define VDSO_HAS_CLOCK_GETRES 1
#define __VDSO_USE_SYSCALL ULLONG_MAX
#ifdef CONFIG_MIPS_CLOCK_VSYSCALL
static __always_inline long gettimeofday_fallback(
@ -205,7 +207,7 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
break;
#endif
default:
cycle_now = 0;
cycle_now = __VDSO_USE_SYSCALL;
break;
}