Unverified Commit 8a1bef41 authored Oct 16, 2019 by Vincenzo Frascino Committed by Paul Burton Oct 18, 2019

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

parent 0ad8f7aa

arch/mips/include/asm/vdso/gettimeofday.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -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;
		}

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