Commit 97884ca8c2925d14c32188e865069f21378b4b4f upstream.
[this is a redesign rather than a backport]
We have a class of errata (grouped under the ARM64_WORKAROUND_1418040 banner) that force the trapping of counter access from 32bit EL0.
We would normally disable the whole vdso for such defect, except that it would disable it for 64bit userspace as well, which is a shame.
Instead, add a new vdso_clock_mode, which signals that the vdso isn't usable for compat tasks. This gets checked in the __arch_get_hw_counter() helper.
Signed-off-by: Marc Zyngier maz@kernel.org Acked-by: Mark Rutland mark.rutland@arm.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200706163802.1836732-2-maz@kernel.org Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Marc Zyngier maz@kernel.org --- arch/arm/include/asm/clocksource.h | 11 ++++++++++- arch/arm/kernel/vdso.c | 2 +- arch/arm64/include/asm/clocksource.h | 5 ++++- arch/arm64/include/asm/vdso/clocksource.h | 14 ++++++++++++++ arch/arm64/include/asm/vdso/compat_gettimeofday.h | 5 +++-- arch/arm64/include/asm/vdso/gettimeofday.h | 6 ++++-- arch/arm64/include/asm/vdso/vsyscall.h | 4 +--- drivers/clocksource/arm_arch_timer.c | 8 ++++---- 8 files changed, 41 insertions(+), 14 deletions(-) create mode 100644 arch/arm64/include/asm/vdso/clocksource.h
diff --git a/arch/arm/include/asm/clocksource.h b/arch/arm/include/asm/clocksource.h index 0b350a7e26f3..afb7a59828fe 100644 --- a/arch/arm/include/asm/clocksource.h +++ b/arch/arm/include/asm/clocksource.h @@ -1,8 +1,17 @@ #ifndef _ASM_CLOCKSOURCE_H #define _ASM_CLOCKSOURCE_H
+enum vdso_arch_clockmode { + /* vdso clocksource not usable */ + VDSO_CLOCKMODE_NONE, + /* vdso clocksource usable */ + VDSO_CLOCKMODE_ARCHTIMER, + VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT = VDSO_CLOCKMODE_ARCHTIMER, +}; + struct arch_clocksource_data { - bool vdso_direct; /* Usable for direct VDSO access? */ + /* Usable for direct VDSO access? */ + enum vdso_arch_clockmode clock_mode; };
#endif diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c index f00e45fa62c4..6c69a5548ba2 100644 --- a/arch/arm/kernel/vdso.c +++ b/arch/arm/kernel/vdso.c @@ -281,7 +281,7 @@ static bool tk_is_cntvct(const struct timekeeper *tk) if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER)) return false;
- if (!tk->tkr_mono.clock->archdata.vdso_direct) + if (tk->tkr_mono.clock->archdata.clock_mode != VDSO_CLOCKMODE_ARCHTIMER) return false;
return true; diff --git a/arch/arm64/include/asm/clocksource.h b/arch/arm64/include/asm/clocksource.h index 0ece64a26c8c..0c7910447235 100644 --- a/arch/arm64/include/asm/clocksource.h +++ b/arch/arm64/include/asm/clocksource.h @@ -2,8 +2,11 @@ #ifndef _ASM_CLOCKSOURCE_H #define _ASM_CLOCKSOURCE_H
+#include <asm/vdso/clocksource.h> + struct arch_clocksource_data { - bool vdso_direct; /* Usable for direct VDSO access? */ + /* Usable for direct VDSO access? */ + enum vdso_arch_clockmode clock_mode; };
#endif diff --git a/arch/arm64/include/asm/vdso/clocksource.h b/arch/arm64/include/asm/vdso/clocksource.h new file mode 100644 index 000000000000..8019f616e1f7 --- /dev/null +++ b/arch/arm64/include/asm/vdso/clocksource.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_VDSOCLOCKSOURCE_H +#define __ASM_VDSOCLOCKSOURCE_H + +enum vdso_arch_clockmode { + /* vdso clocksource not usable */ + VDSO_CLOCKMODE_NONE, + /* vdso clocksource for both 32 and 64bit tasks */ + VDSO_CLOCKMODE_ARCHTIMER, + /* vdso clocksource for 64bit tasks only */ + VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT, +}; + +#endif diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h index c50ee1b7d5cd..413d42e197c7 100644 --- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h +++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h @@ -10,6 +10,7 @@ #include <asm/unistd.h> #include <uapi/linux/time.h>
+#include <asm/vdso/clocksource.h> #include <asm/vdso/compat_barrier.h>
#define __VDSO_USE_SYSCALL ULLONG_MAX @@ -117,10 +118,10 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode) u64 res;
/* - * clock_mode == 0 implies that vDSO are enabled otherwise + * clock_mode == ARCHTIMER implies that vDSO are enabled otherwise * fallback on syscall. */ - if (clock_mode) + if (clock_mode != VDSO_CLOCKMODE_ARCHTIMER) return __VDSO_USE_SYSCALL;
/* diff --git a/arch/arm64/include/asm/vdso/gettimeofday.h b/arch/arm64/include/asm/vdso/gettimeofday.h index b08f476b72b4..ff83b8b574fc 100644 --- a/arch/arm64/include/asm/vdso/gettimeofday.h +++ b/arch/arm64/include/asm/vdso/gettimeofday.h @@ -10,6 +10,8 @@ #include <asm/unistd.h> #include <uapi/linux/time.h>
+#include <asm/vdso/clocksource.h> + #define __VDSO_USE_SYSCALL ULLONG_MAX
#define VDSO_HAS_CLOCK_GETRES 1 @@ -71,10 +73,10 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode) u64 res;
/* - * clock_mode == 0 implies that vDSO are enabled otherwise + * clock_mode != NONE implies that vDSO are enabled otherwise * fallback on syscall. */ - if (clock_mode) + if (clock_mode == VDSO_CLOCKMODE_NONE) return __VDSO_USE_SYSCALL;
/* diff --git a/arch/arm64/include/asm/vdso/vsyscall.h b/arch/arm64/include/asm/vdso/vsyscall.h index 0c20a7c1bee5..e50f26741946 100644 --- a/arch/arm64/include/asm/vdso/vsyscall.h +++ b/arch/arm64/include/asm/vdso/vsyscall.h @@ -24,9 +24,7 @@ struct vdso_data *__arm64_get_k_vdso_data(void) static __always_inline int __arm64_get_clock_mode(struct timekeeper *tk) { - u32 use_syscall = !tk->tkr_mono.clock->archdata.vdso_direct; - - return use_syscall; + return tk->tkr_mono.clock->archdata.clock_mode; } #define __arch_get_clock_mode __arm64_get_clock_mode
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 9a5464c625b4..909fe093249e 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -69,7 +69,7 @@ static enum arch_timer_ppi_nr arch_timer_uses_ppi = ARCH_TIMER_VIRT_PPI; static bool arch_timer_c3stop; static bool arch_timer_mem_use_virtual; static bool arch_counter_suspend_stop; -static bool vdso_default = true; +static enum vdso_arch_clockmode vdso_default = VDSO_CLOCKMODE_ARCHTIMER;
static cpumask_t evtstrm_available = CPU_MASK_NONE; static bool evtstrm_enable = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM); @@ -560,8 +560,8 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa * change both the default value and the vdso itself. */ if (wa->read_cntvct_el0) { - clocksource_counter.archdata.vdso_direct = false; - vdso_default = false; + clocksource_counter.archdata.clock_mode = VDSO_CLOCKMODE_NONE; + vdso_default = VDSO_CLOCKMODE_NONE; } }
@@ -979,7 +979,7 @@ static void __init arch_counter_register(unsigned type) }
arch_timer_read_counter = rd; - clocksource_counter.archdata.vdso_direct = vdso_default; + clocksource_counter.archdata.clock_mode = vdso_default; } else { arch_timer_read_counter = arch_counter_get_cntvct_mem; }