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 --- tools/perf/util/block-range.c | 332 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 332 insertions(+) create mode 100644 tools/perf/util/block-range.c (limited to 'tools/perf/util/block-range.c') diff --git a/tools/perf/util/block-range.c b/tools/perf/util/block-range.c new file mode 100644 index 000000000..7c559fcfd --- /dev/null +++ b/tools/perf/util/block-range.c @@ -0,0 +1,332 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "block-range.h" +#include "annotate.h" +#include +#include + +static struct { + struct rb_root root; + u64 blocks; +} block_ranges; + +static void block_range__debug(void) +{ +#ifndef NDEBUG + struct rb_node *rb; + u64 old = 0; /* NULL isn't executable */ + + for (rb = rb_first(&block_ranges.root); rb; rb = rb_next(rb)) { + struct block_range *entry = rb_entry(rb, struct block_range, node); + + assert(old < entry->start); + assert(entry->start <= entry->end); /* single instruction block; jump to a jump */ + + old = entry->end; + } +#endif +} + +struct block_range *block_range__find(u64 addr) +{ + struct rb_node **p = &block_ranges.root.rb_node; + struct rb_node *parent = NULL; + struct block_range *entry; + + while (*p != NULL) { + parent = *p; + entry = rb_entry(parent, struct block_range, node); + + if (addr < entry->start) + p = &parent->rb_left; + else if (addr > entry->end) + p = &parent->rb_right; + else + return entry; + } + + return NULL; +} + +static inline void rb_link_left_of_node(struct rb_node *left, struct rb_node *node) +{ + struct rb_node **p = &node->rb_left; + while (*p) { + node = *p; + p = &node->rb_right; + } + rb_link_node(left, node, p); +} + +static inline void rb_link_right_of_node(struct rb_node *right, struct rb_node *node) +{ + struct rb_node **p = &node->rb_right; + while (*p) { + node = *p; + p = &node->rb_left; + } + rb_link_node(right, node, p); +} + +/** + * block_range__create + * @start: branch target starting this basic block + * @end: branch ending this basic block + * + * Create all the required block ranges to precisely span the given range. + */ +struct block_range_iter block_range__create(u64 start, u64 end) +{ + struct rb_node **p = &block_ranges.root.rb_node; + struct rb_node *n, *parent = NULL; + struct block_range *next, *entry = NULL; + struct block_range_iter iter = { NULL, NULL }; + + while (*p != NULL) { + parent = *p; + entry = rb_entry(parent, struct block_range, node); + + if (start < entry->start) + p = &parent->rb_left; + else if (start > entry->end) + p = &parent->rb_right; + else + break; + } + + /* + * Didn't find anything.. there's a hole at @start, however @end might + * be inside/behind the next range. + */ + if (!*p) { + if (!entry) /* tree empty */ + goto do_whole; + + /* + * If the last node is before, advance one to find the next. + */ + n = parent; + if (entry->end < start) { + n = rb_next(n); + if (!n) + goto do_whole; + } + next = rb_entry(n, struct block_range, node); + + if (next->start <= end) { /* add head: [start...][n->start...] */ + struct block_range *head = malloc(sizeof(struct block_range)); + if (!head) + return iter; + + *head = (struct block_range){ + .start = start, + .end = next->start - 1, + .is_target = 1, + .is_branch = 0, + }; + + rb_link_left_of_node(&head->node, &next->node); + rb_insert_color(&head->node, &block_ranges.root); + block_range__debug(); + + iter.start = head; + goto do_tail; + } + +do_whole: + /* + * The whole [start..end] range is non-overlapping. + */ + entry = malloc(sizeof(struct block_range)); + if (!entry) + return iter; + + *entry = (struct block_range){ + .start = start, + .end = end, + .is_target = 1, + .is_branch = 1, + }; + + rb_link_node(&entry->node, parent, p); + rb_insert_color(&entry->node, &block_ranges.root); + block_range__debug(); + + iter.start = entry; + iter.end = entry; + goto done; + } + + /* + * We found a range that overlapped with ours, split if needed. + */ + if (entry->start < start) { /* split: [e->start...][start...] */ + struct block_range *head = malloc(sizeof(struct block_range)); + if (!head) + return iter; + + *head = (struct block_range){ + .start = entry->start, + .end = start - 1, + .is_target = entry->is_target, + .is_branch = 0, + + .coverage = entry->coverage, + .entry = entry->entry, + }; + + entry->start = start; + entry->is_target = 1; + entry->entry = 0; + + rb_link_left_of_node(&head->node, &entry->node); + rb_insert_color(&head->node, &block_ranges.root); + block_range__debug(); + + } else if (entry->start == start) + entry->is_target = 1; + + iter.start = entry; + +do_tail: + /* + * At this point we've got: @iter.start = [@start...] but @end can still be + * inside or beyond it. + */ + entry = iter.start; + for (;;) { + /* + * If @end is inside @entry, split. + */ + if (end < entry->end) { /* split: [...end][...e->end] */ + struct block_range *tail = malloc(sizeof(struct block_range)); + if (!tail) + return iter; + + *tail = (struct block_range){ + .start = end + 1, + .end = entry->end, + .is_target = 0, + .is_branch = entry->is_branch, + + .coverage = entry->coverage, + .taken = entry->taken, + .pred = entry->pred, + }; + + entry->end = end; + entry->is_branch = 1; + entry->taken = 0; + entry->pred = 0; + + rb_link_right_of_node(&tail->node, &entry->node); + rb_insert_color(&tail->node, &block_ranges.root); + block_range__debug(); + + iter.end = entry; + goto done; + } + + /* + * If @end matches @entry, done + */ + if (end == entry->end) { + entry->is_branch = 1; + iter.end = entry; + goto done; + } + + next = block_range__next(entry); + if (!next) + goto add_tail; + + /* + * If @end is in beyond @entry but not inside @next, add tail. + */ + if (end < next->start) { /* add tail: [...e->end][...end] */ + struct block_range *tail; +add_tail: + tail = malloc(sizeof(struct block_range)); + if (!tail) + return iter; + + *tail = (struct block_range){ + .start = entry->end + 1, + .end = end, + .is_target = 0, + .is_branch = 1, + }; + + rb_link_right_of_node(&tail->node, &entry->node); + rb_insert_color(&tail->node, &block_ranges.root); + block_range__debug(); + + iter.end = tail; + goto done; + } + + /* + * If there is a hole between @entry and @next, fill it. + */ + if (entry->end + 1 != next->start) { + struct block_range *hole = malloc(sizeof(struct block_range)); + if (!hole) + return iter; + + *hole = (struct block_range){ + .start = entry->end + 1, + .end = next->start - 1, + .is_target = 0, + .is_branch = 0, + }; + + rb_link_left_of_node(&hole->node, &next->node); + rb_insert_color(&hole->node, &block_ranges.root); + block_range__debug(); + } + + entry = next; + } + +done: + assert(iter.start->start == start && iter.start->is_target); + assert(iter.end->end == end && iter.end->is_branch); + + block_ranges.blocks++; + + return iter; +} + + +/* + * Compute coverage as: + * + * br->coverage / br->sym->max_coverage + * + * This ensures each symbol has a 100% spot, to reflect that each symbol has a + * most covered section. + * + * Returns [0-1] for coverage and -1 if we had no data what so ever or the + * symbol does not exist. + */ +double block_range__coverage(struct block_range *br) +{ + struct symbol *sym; + struct annotated_branch *branch; + + if (!br) { + if (block_ranges.blocks) + return 0; + + return -1; + } + + sym = br->sym; + if (!sym) + return -1; + + branch = symbol__annotation(sym)->branch; + if (!branch) + return -1; + + return (double)br->coverage / branch->max_coverage; +} -- cgit v1.3.1