[tip: timers/core] clocksource/drivers/arm_arch_timer: Fix MMIO base address vs callback ordering issue

tip-bot2 for Marc Zyngier
2021-10-24T15:40:33Z

The following commit has been merged into the timers/core branch of tip:

Commit-ID: 72f47a3f0ea4cda4ca5d90c0d6043f697b9b0647
Gitweb: https://git.kernel.org/tip/72f47a3f0ea4cda4ca5d90c0d6043f697b9b0647
Author: Marc Zyngier <maz@kernel.org>
AuthorDate: Sun, 17 Oct 2021 13:42:14 +01:00
Committer: Daniel Lezcano <daniel.lezcano@linaro.org>
CommitterDate: Sun, 17 Oct 2021 21:47:15 +02:00

clocksource/drivers/arm_arch_timer: Fix MMIO base address vs callback ordering issue

The MMIO timer base address gets published after we have registered
the callbacks and the interrupt handler, which is... a bit dangerous.

Fix this by moving the base address publication to the point where
we register the timer, and expose a pointer to the timer structure
itself rather than a naked value.

Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-7-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
drivers/clocksource/arm_arch_timer.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 8afe8c8..bede10f 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -54,13 +54,13 @@

static unsigned arch_timers_present __initdata;

-static void __iomem *arch_counter_base __ro_after_init;
-
struct arch_timer {
void __iomem *base;
struct clock_event_device evt;
};

+static struct arch_timer *arch_timer_mem __ro_after_init;
+
#define to_arch_timer(e) container_of(e, struct arch_timer, evt)

static u32 arch_timer_rate __ro_after_init;
@@ -973,9 +973,9 @@ static u64 arch_counter_get_cntvct_mem(void)
u32 vct_lo, vct_hi, tmp_hi;

do {
- vct_hi = readl_relaxed(arch_counter_base + CNTVCT_HI);
- vct_lo = readl_relaxed(arch_counter_base + CNTVCT_LO);
- tmp_hi = readl_relaxed(arch_counter_base + CNTVCT_HI);
+ vct_hi = readl_relaxed(arch_timer_mem->base + CNTVCT_HI);
+ vct_lo = readl_relaxed(arch_timer_mem->base + CNTVCT_LO);
+ tmp_hi = readl_relaxed(arch_timer_mem->base + CNTVCT_HI);
} while (vct_hi != tmp_hi);

return ((u64) vct_hi << 32) | vct_lo;
@@ -1166,25 +1166,25 @@ static int __init arch_timer_mem_register(void __iomem *base, unsigned int irq)
{
int ret;
irq_handler_t func;
- struct arch_timer *t;

- t = kzalloc(sizeof(*t), GFP_KERNEL);
- if (!t)
+ arch_timer_mem = kzalloc(sizeof(*arch_timer_mem), GFP_KERNEL);
+ if (!arch_timer_mem)
return -ENOMEM;

- t->base = base;
- t->evt.irq = irq;
- __arch_timer_setup(ARCH_TIMER_TYPE_MEM, &t->evt);
+ arch_timer_mem->base = base;
+ arch_timer_mem->evt.irq = irq;
+ __arch_timer_setup(ARCH_TIMER_TYPE_MEM, &arch_timer_mem->evt);

if (arch_timer_mem_use_virtual)
func = arch_timer_handler_virt_mem;
else
func = arch_timer_handler_phys_mem;

- ret = request_irq(irq, func, IRQF_TIMER, "arch_mem_timer", &t->evt);
+ ret = request_irq(irq, func, IRQF_TIMER, "arch_mem_timer", &arch_timer_mem->evt);
if (ret) {
pr_err("Failed to request mem timer irq\n");
- kfree(t);
+ kfree(arch_timer_mem);
+ arch_timer_mem = NULL;
}

return ret;
@@ -1442,7 +1442,6 @@ arch_timer_mem_frame_register(struct arch_timer_mem_frame *frame)
return ret;
}

- arch_counter_base = base;
arch_timers_present |= ARCH_TIMER_TYPE_MEM;

return 0;