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-vt8500.c | 150 +++++++++++++++++++++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 drivers/clocksource/timer-vt8500.c (limited to 'drivers/clocksource/timer-vt8500.c') diff --git a/drivers/clocksource/timer-vt8500.c b/drivers/clocksource/timer-vt8500.c new file mode 100644 index 000000000..a469b1b5f --- /dev/null +++ b/drivers/clocksource/timer-vt8500.c @@ -0,0 +1,150 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * arch/arm/mach-vt8500/timer.c + * + * Copyright (C) 2012 Tony Prisk + * Copyright (C) 2010 Alexey Charkov + */ + +/* + * This file is copied and modified from the original timer.c provided by + * Alexey Charkov. Minor changes have been made for Device Tree Support. + */ + +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +#define VT8500_TIMER_OFFSET 0x0100 +#define VT8500_TIMER_HZ 3000000 +#define TIMER_MATCH_VAL 0x0000 +#define TIMER_COUNT_VAL 0x0010 +#define TIMER_STATUS_VAL 0x0014 +#define TIMER_IER_VAL 0x001c /* interrupt enable */ +#define TIMER_CTRL_VAL 0x0020 +#define TIMER_AS_VAL 0x0024 /* access status */ +#define TIMER_COUNT_R_ACTIVE (1 << 5) /* not ready for read */ +#define TIMER_COUNT_W_ACTIVE (1 << 4) /* not ready for write */ +#define TIMER_MATCH_W_ACTIVE (1 << 0) /* not ready for write */ + +#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) + +#define MIN_OSCR_DELTA 16 + +static void __iomem *regbase; + +static u64 vt8500_timer_read(struct clocksource *cs) +{ + int loops = msecs_to_loops(10); + writel(3, regbase + TIMER_CTRL_VAL); + while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE) + && --loops) + cpu_relax(); + return readl(regbase + TIMER_COUNT_VAL); +} + +static struct clocksource clocksource = { + .name = "vt8500_timer", + .rating = 200, + .read = vt8500_timer_read, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static int vt8500_timer_set_next_event(unsigned long cycles, + struct clock_event_device *evt) +{ + int loops = msecs_to_loops(10); + u64 alarm = clocksource.read(&clocksource) + cycles; + while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE) + && --loops) + cpu_relax(); + writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL); + + if ((signed)(alarm - clocksource.read(&clocksource)) <= MIN_OSCR_DELTA) + return -ETIME; + + writel(1, regbase + TIMER_IER_VAL); + + return 0; +} + +static int vt8500_shutdown(struct clock_event_device *evt) +{ + writel(readl(regbase + TIMER_CTRL_VAL) | 1, regbase + TIMER_CTRL_VAL); + writel(0, regbase + TIMER_IER_VAL); + return 0; +} + +static struct clock_event_device clockevent = { + .name = "vt8500_timer", + .features = CLOCK_EVT_FEAT_ONESHOT, + .rating = 200, + .set_next_event = vt8500_timer_set_next_event, + .set_state_shutdown = vt8500_shutdown, + .set_state_oneshot = vt8500_shutdown, +}; + +static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + writel(0xf, regbase + TIMER_STATUS_VAL); + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static int __init vt8500_timer_init(struct device_node *np) +{ + int timer_irq, ret; + + regbase = of_iomap(np, 0); + if (!regbase) { + pr_err("%s: Missing iobase description in Device Tree\n", + __func__); + return -ENXIO; + } + + timer_irq = irq_of_parse_and_map(np, 0); + if (!timer_irq) { + pr_err("%s: Missing irq description in Device Tree\n", + __func__); + return -EINVAL; + } + + writel(1, regbase + TIMER_CTRL_VAL); + writel(0xf, regbase + TIMER_STATUS_VAL); + writel(~0, regbase + TIMER_MATCH_VAL); + + ret = clocksource_register_hz(&clocksource, VT8500_TIMER_HZ); + if (ret) { + pr_err("%s: clocksource_register failed for %s\n", + __func__, clocksource.name); + return ret; + } + + clockevent.cpumask = cpumask_of(0); + + ret = request_irq(timer_irq, vt8500_timer_interrupt, + IRQF_TIMER | IRQF_IRQPOLL, "vt8500_timer", + &clockevent); + if (ret) { + pr_err("%s: setup_irq failed for %s\n", __func__, + clockevent.name); + return ret; + } + + clockevents_config_and_register(&clockevent, VT8500_TIMER_HZ, + MIN_OSCR_DELTA * 2, 0xf0000000); + + return 0; +} + +TIMER_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init); -- cgit v1.3.1