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-integrator-ap.c | 225 ++++++++++++++++++++++++++++++ 1 file changed, 225 insertions(+) create mode 100644 drivers/clocksource/timer-integrator-ap.c (limited to 'drivers/clocksource/timer-integrator-ap.c') diff --git a/drivers/clocksource/timer-integrator-ap.c b/drivers/clocksource/timer-integrator-ap.c new file mode 100644 index 000000000..a4c700b11 --- /dev/null +++ b/drivers/clocksource/timer-integrator-ap.c @@ -0,0 +1,225 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Integrator/AP timer driver + * Copyright (C) 2000-2003 Deep Blue Solutions Ltd + * Copyright (c) 2014, Linaro Limited + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include "timer-sp.h" + +static void __iomem * sched_clk_base; + +static u64 notrace integrator_read_sched_clock(void) +{ + return -readl(sched_clk_base + TIMER_VALUE); +} + +static int __init integrator_clocksource_init(unsigned long inrate, + void __iomem *base) +{ + u32 ctrl = TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC; + unsigned long rate = inrate; + int ret; + + if (rate >= 1500000) { + rate /= 16; + ctrl |= TIMER_CTRL_DIV16; + } + + writel(0xffff, base + TIMER_LOAD); + writel(ctrl, base + TIMER_CTRL); + + ret = clocksource_mmio_init(base + TIMER_VALUE, "timer2", + rate, 200, 16, clocksource_mmio_readl_down); + if (ret) + return ret; + + sched_clk_base = base; + sched_clock_register(integrator_read_sched_clock, 16, rate); + + return 0; +} + +static unsigned long timer_reload; +static void __iomem * clkevt_base; + +/* + * IRQ handler for the timer + */ +static irqreturn_t integrator_timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + + /* clear the interrupt */ + writel(1, clkevt_base + TIMER_INTCLR); + + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static int clkevt_shutdown(struct clock_event_device *evt) +{ + u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE; + + /* Disable timer */ + writel(ctrl, clkevt_base + TIMER_CTRL); + return 0; +} + +static int clkevt_set_oneshot(struct clock_event_device *evt) +{ + u32 ctrl = readl(clkevt_base + TIMER_CTRL) & + ~(TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC); + + /* Leave the timer disabled, .set_next_event will enable it */ + writel(ctrl, clkevt_base + TIMER_CTRL); + return 0; +} + +static int clkevt_set_periodic(struct clock_event_device *evt) +{ + u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE; + + /* Disable timer */ + writel(ctrl, clkevt_base + TIMER_CTRL); + + /* Enable the timer and start the periodic tick */ + writel(timer_reload, clkevt_base + TIMER_LOAD); + ctrl |= TIMER_CTRL_PERIODIC | TIMER_CTRL_ENABLE; + writel(ctrl, clkevt_base + TIMER_CTRL); + return 0; +} + +static int clkevt_set_next_event(unsigned long next, struct clock_event_device *evt) +{ + unsigned long ctrl = readl(clkevt_base + TIMER_CTRL); + + writel(ctrl & ~TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL); + writel(next, clkevt_base + TIMER_LOAD); + writel(ctrl | TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL); + + return 0; +} + +static struct clock_event_device integrator_clockevent = { + .name = "timer1", + .features = CLOCK_EVT_FEAT_PERIODIC | + CLOCK_EVT_FEAT_ONESHOT, + .set_state_shutdown = clkevt_shutdown, + .set_state_periodic = clkevt_set_periodic, + .set_state_oneshot = clkevt_set_oneshot, + .tick_resume = clkevt_shutdown, + .set_next_event = clkevt_set_next_event, + .rating = 300, +}; + +static int integrator_clockevent_init(unsigned long inrate, + void __iomem *base, int irq) +{ + unsigned long rate = inrate; + unsigned int ctrl = 0; + int ret; + + clkevt_base = base; + /* Calculate and program a divisor */ + if (rate > 0x100000 * HZ) { + rate /= 256; + ctrl |= TIMER_CTRL_DIV256; + } else if (rate > 0x10000 * HZ) { + rate /= 16; + ctrl |= TIMER_CTRL_DIV16; + } + timer_reload = rate / HZ; + writel(ctrl, clkevt_base + TIMER_CTRL); + + ret = request_irq(irq, integrator_timer_interrupt, + IRQF_TIMER | IRQF_IRQPOLL, "timer", + &integrator_clockevent); + if (ret) + return ret; + + clockevents_config_and_register(&integrator_clockevent, + rate, + 1, + 0xffffU); + return 0; +} + +static int __init integrator_ap_timer_init_of(struct device_node *node) +{ + const char *path; + void __iomem *base; + int err; + int irq; + struct clk *clk; + unsigned long rate; + struct device_node *alias_node; + + base = of_io_request_and_map(node, 0, "integrator-timer"); + if (IS_ERR(base)) + return PTR_ERR(base); + + clk = of_clk_get(node, 0); + if (IS_ERR(clk)) { + pr_err("No clock for %pOFn\n", node); + return PTR_ERR(clk); + } + clk_prepare_enable(clk); + rate = clk_get_rate(clk); + writel(0, base + TIMER_CTRL); + + err = of_property_read_string(of_aliases, + "arm,timer-primary", &path); + if (err) { + pr_warn("Failed to read property\n"); + return err; + } + + alias_node = of_find_node_by_path(path); + + /* + * The pointer is used as an identifier not as a pointer, we + * can drop the refcount on the of__node immediately after + * getting it. + */ + of_node_put(alias_node); + + if (node == alias_node) + /* The primary timer lacks IRQ, use as clocksource */ + return integrator_clocksource_init(rate, base); + + err = of_property_read_string(of_aliases, + "arm,timer-secondary", &path); + if (err) { + pr_warn("Failed to read property\n"); + return err; + } + + alias_node = of_find_node_by_path(path); + + of_node_put(alias_node); + + if (node == alias_node) { + /* The secondary timer will drive the clock event */ + irq = irq_of_parse_and_map(node, 0); + return integrator_clockevent_init(rate, base, irq); + } + + pr_info("Timer @%p unused\n", base); + clk_disable_unprepare(clk); + + return 0; +} + +TIMER_OF_DECLARE(integrator_ap_timer, "arm,integrator-timer", + integrator_ap_timer_init_of); -- cgit v1.3.1