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/clps711x-timer.c | 110 +++++++++++++++++++++++++++++++++++ 1 file changed, 110 insertions(+) create mode 100644 drivers/clocksource/clps711x-timer.c (limited to 'drivers/clocksource/clps711x-timer.c') diff --git a/drivers/clocksource/clps711x-timer.c b/drivers/clocksource/clps711x-timer.c new file mode 100644 index 000000000..bb0a44ada --- /dev/null +++ b/drivers/clocksource/clps711x-timer.c @@ -0,0 +1,110 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Cirrus Logic CLPS711X clocksource driver + * + * Copyright (C) 2014 Alexander Shiyan + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +enum { + CLPS711X_CLKSRC_CLOCKSOURCE, + CLPS711X_CLKSRC_CLOCKEVENT, +}; + +static void __iomem *tcd; + +static u64 notrace clps711x_sched_clock_read(void) +{ + return ~readw(tcd); +} + +static void __init clps711x_clksrc_init(struct clk *clock, void __iomem *base) +{ + unsigned long rate = clk_get_rate(clock); + + tcd = base; + + clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16, + clocksource_mmio_readw_down); + + sched_clock_register(clps711x_sched_clock_read, 16, rate); +} + +static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base, + unsigned int irq) +{ + struct clock_event_device *clkevt; + unsigned long rate; + + clkevt = kzalloc_obj(*clkevt); + if (!clkevt) + return -ENOMEM; + + rate = clk_get_rate(clock); + + /* Set Timer prescaler */ + writew(DIV_ROUND_CLOSEST(rate, HZ), base); + + clkevt->name = "clps711x-clockevent"; + clkevt->rating = 300; + clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP; + clkevt->cpumask = cpumask_of(0); + clockevents_config_and_register(clkevt, HZ, 0, 0); + + return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER, + "clps711x-timer", clkevt); +} + +static int __init clps711x_timer_init(struct device_node *np) +{ + unsigned int irq = irq_of_parse_and_map(np, 0); + struct clk *clock = of_clk_get(np, 0); + void __iomem *base = of_iomap(np, 0); + int ret = 0; + + if (!base) + return -ENOMEM; + if (!irq) { + ret = -EINVAL; + goto unmap_io; + } + if (IS_ERR(clock)) { + ret = PTR_ERR(clock); + goto unmap_io; + } + + switch (of_alias_get_id(np, "timer")) { + case CLPS711X_CLKSRC_CLOCKSOURCE: + clps711x_clksrc_init(clock, base); + break; + case CLPS711X_CLKSRC_CLOCKEVENT: + ret = _clps711x_clkevt_init(clock, base, irq); + break; + default: + ret = -EINVAL; + break; + } + +unmap_io: + iounmap(base); + return ret; +} +TIMER_OF_DECLARE(clps711x, "cirrus,ep7209-timer", clps711x_timer_init); -- cgit v1.3.1