From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- drivers/clocksource/timer-goldfish.c | 153 +++++++++++++++++++++++++++++++++++ 1 file changed, 153 insertions(+) create mode 100644 drivers/clocksource/timer-goldfish.c (limited to 'drivers/clocksource/timer-goldfish.c') diff --git a/drivers/clocksource/timer-goldfish.c b/drivers/clocksource/timer-goldfish.c new file mode 100644 index 000000000..3fe12c7ee --- /dev/null +++ b/drivers/clocksource/timer-goldfish.c @@ -0,0 +1,153 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include +#include +#include +#include + +struct goldfish_timer { + struct clocksource cs; + struct clock_event_device ced; + struct resource res; + void __iomem *base; +}; + +static struct goldfish_timer *ced_to_gf(struct clock_event_device *ced) +{ + return container_of(ced, struct goldfish_timer, ced); +} + +static struct goldfish_timer *cs_to_gf(struct clocksource *cs) +{ + return container_of(cs, struct goldfish_timer, cs); +} + +static u64 goldfish_timer_read(struct clocksource *cs) +{ + struct goldfish_timer *timerdrv = cs_to_gf(cs); + void __iomem *base = timerdrv->base; + u32 time_low, time_high; + u64 ticks; + + /* + * time_low: get low bits of current time and update time_high + * time_high: get high bits of time at last time_low read + */ + time_low = gf_ioread32(base + TIMER_TIME_LOW); + time_high = gf_ioread32(base + TIMER_TIME_HIGH); + + ticks = ((u64)time_high << 32) | time_low; + + return ticks; +} + +static int goldfish_timer_set_oneshot(struct clock_event_device *evt) +{ + struct goldfish_timer *timerdrv = ced_to_gf(evt); + void __iomem *base = timerdrv->base; + + gf_iowrite32(0, base + TIMER_ALARM_HIGH); + gf_iowrite32(0, base + TIMER_ALARM_LOW); + gf_iowrite32(1, base + TIMER_IRQ_ENABLED); + + return 0; +} + +static int goldfish_timer_shutdown(struct clock_event_device *evt) +{ + struct goldfish_timer *timerdrv = ced_to_gf(evt); + void __iomem *base = timerdrv->base; + + gf_iowrite32(0, base + TIMER_IRQ_ENABLED); + + return 0; +} + +static int goldfish_timer_next_event(unsigned long delta, + struct clock_event_device *evt) +{ + struct goldfish_timer *timerdrv = ced_to_gf(evt); + void __iomem *base = timerdrv->base; + u64 now; + + now = goldfish_timer_read(&timerdrv->cs); + + now += delta; + + gf_iowrite32(upper_32_bits(now), base + TIMER_ALARM_HIGH); + gf_iowrite32(lower_32_bits(now), base + TIMER_ALARM_LOW); + + return 0; +} + +static irqreturn_t goldfish_timer_irq(int irq, void *dev_id) +{ + struct goldfish_timer *timerdrv = dev_id; + struct clock_event_device *evt = &timerdrv->ced; + void __iomem *base = timerdrv->base; + + gf_iowrite32(1, base + TIMER_CLEAR_INTERRUPT); + + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +int __init goldfish_timer_init(int irq, void __iomem *base) +{ + struct goldfish_timer *timerdrv; + int ret; + + timerdrv = kzalloc_obj(*timerdrv); + if (!timerdrv) + return -ENOMEM; + + timerdrv->base = base; + + timerdrv->ced = (struct clock_event_device){ + .name = "goldfish_timer", + .features = CLOCK_EVT_FEAT_ONESHOT, + .set_state_shutdown = goldfish_timer_shutdown, + .set_state_oneshot = goldfish_timer_set_oneshot, + .set_next_event = goldfish_timer_next_event, + }; + + timerdrv->res = (struct resource){ + .name = "goldfish_timer", + .start = (unsigned long)base, + .end = (unsigned long)base + 0xfff, + }; + + ret = request_resource(&iomem_resource, &timerdrv->res); + if (ret) { + pr_err("Cannot allocate '%s' resource\n", timerdrv->res.name); + return ret; + } + + timerdrv->cs = (struct clocksource){ + .name = "goldfish_timer", + .rating = 400, + .read = goldfish_timer_read, + .mask = CLOCKSOURCE_MASK(64), + .flags = 0, + .max_idle_ns = LONG_MAX, + }; + + clocksource_register_hz(&timerdrv->cs, NSEC_PER_SEC); + + ret = request_irq(irq, goldfish_timer_irq, IRQF_TIMER, + "goldfish_timer", timerdrv); + if (ret) { + pr_err("Couldn't register goldfish-timer interrupt\n"); + return ret; + } + + clockevents_config_and_register(&timerdrv->ced, NSEC_PER_SEC, + 1, 0xffffffff); + + return 0; +} -- cgit v1.3.1