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 --- samples/damon/prcl.c | 169 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 169 insertions(+) create mode 100644 samples/damon/prcl.c (limited to 'samples/damon/prcl.c') diff --git a/samples/damon/prcl.c b/samples/damon/prcl.c new file mode 100644 index 000000000..b7c50f265 --- /dev/null +++ b/samples/damon/prcl.c @@ -0,0 +1,169 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * proactive reclamation: monitor access pattern of a given process, find + * regions that seems not accessed, and proactively page out the regions. + */ + +#define pr_fmt(fmt) "damon_sample_prcl: " fmt + +#include +#include +#include +#include + +#ifdef MODULE_PARAM_PREFIX +#undef MODULE_PARAM_PREFIX +#endif +#define MODULE_PARAM_PREFIX "damon_sample_prcl." + +static int target_pid __read_mostly; +module_param(target_pid, int, 0600); + +static int damon_sample_prcl_enable_store( + const char *val, const struct kernel_param *kp); + +static const struct kernel_param_ops enabled_param_ops = { + .set = damon_sample_prcl_enable_store, + .get = param_get_bool, +}; + +static bool enabled __read_mostly; +module_param_cb(enabled, &enabled_param_ops, &enabled, 0600); +MODULE_PARM_DESC(enabled, "Enable or disable DAMON_SAMPLE_PRCL"); + +static struct damon_ctx *ctx; +static struct pid *target_pidp; + +static int damon_sample_prcl_repeat_call_fn(void *data) +{ + struct damon_ctx *c = data; + struct damon_target *t; + + damon_for_each_target(t, c) { + struct damon_region *r; + unsigned long wss = 0; + + damon_for_each_region(r, t) { + if (r->nr_accesses > 0) + wss += r->ar.end - r->ar.start; + } + pr_info("wss: %lu\n", wss); + } + return 0; +} + +static struct damon_call_control repeat_call_control = { + .fn = damon_sample_prcl_repeat_call_fn, + .repeat = true, +}; + +static int damon_sample_prcl_start(void) +{ + struct damon_target *target; + struct damos *scheme; + int err; + + pr_info("start\n"); + + ctx = damon_new_ctx(); + if (!ctx) + return -ENOMEM; + if (damon_select_ops(ctx, DAMON_OPS_VADDR)) { + damon_destroy_ctx(ctx); + return -EINVAL; + } + + target = damon_new_target(); + if (!target) { + damon_destroy_ctx(ctx); + return -ENOMEM; + } + damon_add_target(ctx, target); + target_pidp = find_get_pid(target_pid); + if (!target_pidp) { + damon_destroy_ctx(ctx); + return -EINVAL; + } + target->pid = target_pidp; + + scheme = damon_new_scheme( + &(struct damos_access_pattern) { + .min_sz_region = PAGE_SIZE, + .max_sz_region = ULONG_MAX, + .min_nr_accesses = 0, + .max_nr_accesses = 0, + .min_age_region = 50, + .max_age_region = UINT_MAX}, + DAMOS_PAGEOUT, + 0, + &(struct damos_quota){}, + &(struct damos_watermarks){}, + NUMA_NO_NODE); + if (!scheme) { + damon_destroy_ctx(ctx); + return -ENOMEM; + } + damon_set_schemes(ctx, &scheme, 1); + + err = damon_start(&ctx, 1, true); + if (err) + return err; + + repeat_call_control.data = ctx; + return damon_call(ctx, &repeat_call_control); +} + +static void damon_sample_prcl_stop(void) +{ + pr_info("stop\n"); + if (ctx) { + damon_stop(&ctx, 1); + damon_destroy_ctx(ctx); + } +} + +static int damon_sample_prcl_enable_store( + const char *val, const struct kernel_param *kp) +{ + bool is_enabled = enabled; + int err; + + err = kstrtobool(val, &enabled); + if (err) + return err; + + if (enabled == is_enabled) + return 0; + + if (!damon_initialized()) + return 0; + + if (enabled) { + err = damon_sample_prcl_start(); + if (err) + enabled = false; + return err; + } + damon_sample_prcl_stop(); + return 0; +} + +static int __init damon_sample_prcl_init(void) +{ + int err = 0; + + if (!damon_initialized()) { + if (enabled) + enabled = false; + return -ENOMEM; + } + + if (enabled) { + err = damon_sample_prcl_start(); + if (err) + enabled = false; + } + return 0; +} + +module_init(damon_sample_prcl_init); -- cgit v1.3.1