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 --- lib/test_ida.c | 288 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 288 insertions(+) create mode 100644 lib/test_ida.c (limited to 'lib/test_ida.c') diff --git a/lib/test_ida.c b/lib/test_ida.c new file mode 100644 index 000000000..63078f8dc --- /dev/null +++ b/lib/test_ida.c @@ -0,0 +1,288 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * test_ida.c: Test the IDA API + * Copyright (c) 2016-2018 Microsoft Corporation + * Copyright (c) 2018 Oracle Corporation + * Author: Matthew Wilcox + */ + +#include +#include + +static unsigned int tests_run; +static unsigned int tests_passed; + +#ifdef __KERNEL__ +static void ida_dump(struct ida *ida) { } +#endif +#define IDA_BUG_ON(ida, x) do { \ + tests_run++; \ + if (x) { \ + ida_dump(ida); \ + dump_stack(); \ + } else { \ + tests_passed++; \ + } \ +} while (0) + +/* + * Straightforward checks that allocating and freeing IDs work. + */ +static void ida_check_alloc(struct ida *ida) +{ + int i, id; + + for (i = 0; i < 10000; i++) + IDA_BUG_ON(ida, ida_alloc(ida, GFP_KERNEL) != i); + + ida_free(ida, 20); + ida_free(ida, 21); + for (i = 0; i < 3; i++) { + id = ida_alloc(ida, GFP_KERNEL); + IDA_BUG_ON(ida, id < 0); + if (i == 2) + IDA_BUG_ON(ida, id != 10000); + } + + for (i = 0; i < 5000; i++) + ida_free(ida, i); + + IDA_BUG_ON(ida, ida_alloc_min(ida, 5000, GFP_KERNEL) != 10001); + ida_destroy(ida); + + IDA_BUG_ON(ida, !ida_is_empty(ida)); +} + +/* Destroy an IDA with a single entry at @base */ +static void ida_check_destroy_1(struct ida *ida, unsigned int base) +{ + IDA_BUG_ON(ida, ida_alloc_min(ida, base, GFP_KERNEL) != base); + IDA_BUG_ON(ida, ida_is_empty(ida)); + ida_destroy(ida); + IDA_BUG_ON(ida, !ida_is_empty(ida)); +} + +/* Check that ida_destroy and ida_is_empty work */ +static void ida_check_destroy(struct ida *ida) +{ + /* Destroy an already-empty IDA */ + IDA_BUG_ON(ida, !ida_is_empty(ida)); + ida_destroy(ida); + IDA_BUG_ON(ida, !ida_is_empty(ida)); + + ida_check_destroy_1(ida, 0); + ida_check_destroy_1(ida, 1); + ida_check_destroy_1(ida, 1023); + ida_check_destroy_1(ida, 1024); + ida_check_destroy_1(ida, 12345678); +} + +/* + * Check what happens when we fill a leaf and then delete it. This may + * discover mishandling of IDR_FREE. + */ +static void ida_check_leaf(struct ida *ida, unsigned int base) +{ + unsigned long i; + + for (i = 0; i < IDA_BITMAP_BITS; i++) { + IDA_BUG_ON(ida, ida_alloc_min(ida, base, GFP_KERNEL) != + base + i); + } + + ida_destroy(ida); + IDA_BUG_ON(ida, !ida_is_empty(ida)); + + IDA_BUG_ON(ida, ida_alloc(ida, GFP_KERNEL) != 0); + IDA_BUG_ON(ida, ida_is_empty(ida)); + ida_free(ida, 0); + IDA_BUG_ON(ida, !ida_is_empty(ida)); +} + +/* + * Check allocations up to and slightly above the maximum allowed (2^31-1) ID. + * Allocating up to 2^31-1 should succeed, and then allocating the next one + * should fail. + */ +static void ida_check_max(struct ida *ida) +{ + unsigned long i, j; + + for (j = 1; j < 65537; j *= 2) { + unsigned long base = (1UL << 31) - j; + for (i = 0; i < j; i++) { + IDA_BUG_ON(ida, ida_alloc_min(ida, base, GFP_KERNEL) != + base + i); + } + IDA_BUG_ON(ida, ida_alloc_min(ida, base, GFP_KERNEL) != + -ENOSPC); + ida_destroy(ida); + IDA_BUG_ON(ida, !ida_is_empty(ida)); + } +} + +/* + * Check handling of conversions between exceptional entries and full bitmaps. + */ +static void ida_check_conv(struct ida *ida) +{ + unsigned long i; + + for (i = 0; i < IDA_BITMAP_BITS * 2; i += IDA_BITMAP_BITS) { + IDA_BUG_ON(ida, ida_alloc_min(ida, i + 1, GFP_KERNEL) != i + 1); + IDA_BUG_ON(ida, ida_alloc_min(ida, i + BITS_PER_LONG, + GFP_KERNEL) != i + BITS_PER_LONG); + ida_free(ida, i + 1); + ida_free(ida, i + BITS_PER_LONG); + IDA_BUG_ON(ida, !ida_is_empty(ida)); + } + + for (i = 0; i < IDA_BITMAP_BITS * 2; i++) + IDA_BUG_ON(ida, ida_alloc(ida, GFP_KERNEL) != i); + for (i = IDA_BITMAP_BITS * 2; i > 0; i--) + ida_free(ida, i - 1); + IDA_BUG_ON(ida, !ida_is_empty(ida)); + + for (i = 0; i < IDA_BITMAP_BITS + BITS_PER_LONG - 4; i++) + IDA_BUG_ON(ida, ida_alloc(ida, GFP_KERNEL) != i); + for (i = IDA_BITMAP_BITS + BITS_PER_LONG - 4; i > 0; i--) + ida_free(ida, i - 1); + IDA_BUG_ON(ida, !ida_is_empty(ida)); +} + +/* + * Check various situations where we attempt to free an ID we don't own. + */ +static void ida_check_bad_free(struct ida *ida) +{ + unsigned long i; + + printk("vvv Ignore \"not allocated\" warnings\n"); + /* IDA is empty; all of these will fail */ + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + + /* IDA contains a single value entry */ + IDA_BUG_ON(ida, ida_alloc_min(ida, 3, GFP_KERNEL) != 3); + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + + /* IDA contains a single bitmap */ + IDA_BUG_ON(ida, ida_alloc_min(ida, 1023, GFP_KERNEL) != 1023); + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + + /* IDA contains a tree */ + IDA_BUG_ON(ida, ida_alloc_min(ida, (1 << 20) - 1, GFP_KERNEL) != (1 << 20) - 1); + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + printk("^^^ \"not allocated\" warnings over\n"); + + ida_free(ida, 3); + ida_free(ida, 1023); + ida_free(ida, (1 << 20) - 1); + + IDA_BUG_ON(ida, !ida_is_empty(ida)); +} + +/* + * Check ida_find_first_range() and varriants. + */ +static void ida_check_find_first(struct ida *ida) +{ + /* IDA is empty; all of the below should be not exist */ + IDA_BUG_ON(ida, ida_exists(ida, 0)); + IDA_BUG_ON(ida, ida_exists(ida, 3)); + IDA_BUG_ON(ida, ida_exists(ida, 63)); + IDA_BUG_ON(ida, ida_exists(ida, 1023)); + IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1)); + + /* IDA contains a single value entry */ + IDA_BUG_ON(ida, ida_alloc_min(ida, 3, GFP_KERNEL) != 3); + IDA_BUG_ON(ida, ida_exists(ida, 0)); + IDA_BUG_ON(ida, !ida_exists(ida, 3)); + IDA_BUG_ON(ida, ida_exists(ida, 63)); + IDA_BUG_ON(ida, ida_exists(ida, 1023)); + IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1)); + + IDA_BUG_ON(ida, ida_alloc_min(ida, 63, GFP_KERNEL) != 63); + IDA_BUG_ON(ida, ida_exists(ida, 0)); + IDA_BUG_ON(ida, !ida_exists(ida, 3)); + IDA_BUG_ON(ida, !ida_exists(ida, 63)); + IDA_BUG_ON(ida, ida_exists(ida, 1023)); + IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1)); + + /* IDA contains a single bitmap */ + IDA_BUG_ON(ida, ida_alloc_min(ida, 1023, GFP_KERNEL) != 1023); + IDA_BUG_ON(ida, ida_exists(ida, 0)); + IDA_BUG_ON(ida, !ida_exists(ida, 3)); + IDA_BUG_ON(ida, !ida_exists(ida, 63)); + IDA_BUG_ON(ida, !ida_exists(ida, 1023)); + IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1)); + + /* IDA contains a tree */ + IDA_BUG_ON(ida, ida_alloc_min(ida, (1 << 20) - 1, GFP_KERNEL) != (1 << 20) - 1); + IDA_BUG_ON(ida, ida_exists(ida, 0)); + IDA_BUG_ON(ida, !ida_exists(ida, 3)); + IDA_BUG_ON(ida, !ida_exists(ida, 63)); + IDA_BUG_ON(ida, !ida_exists(ida, 1023)); + IDA_BUG_ON(ida, !ida_exists(ida, (1 << 20) - 1)); + + /* Now try to find first */ + IDA_BUG_ON(ida, ida_find_first(ida) != 3); + IDA_BUG_ON(ida, ida_find_first_range(ida, -1, 2) != -EINVAL); + IDA_BUG_ON(ida, ida_find_first_range(ida, 0, 2) != -ENOENT); // no used ID + IDA_BUG_ON(ida, ida_find_first_range(ida, 0, 3) != 3); + IDA_BUG_ON(ida, ida_find_first_range(ida, 1, 3) != 3); + IDA_BUG_ON(ida, ida_find_first_range(ida, 3, 3) != 3); + IDA_BUG_ON(ida, ida_find_first_range(ida, 2, 4) != 3); + IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 3) != -ENOENT); // min > max, fail + IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 60) != -ENOENT); // no used ID + IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 64) != 63); + IDA_BUG_ON(ida, ida_find_first_range(ida, 63, 63) != 63); + IDA_BUG_ON(ida, ida_find_first_range(ida, 64, 1026) != 1023); + IDA_BUG_ON(ida, ida_find_first_range(ida, 1023, 1023) != 1023); + IDA_BUG_ON(ida, ida_find_first_range(ida, 1023, (1 << 20) - 1) != 1023); + IDA_BUG_ON(ida, ida_find_first_range(ida, 1024, (1 << 20) - 1) != (1 << 20) - 1); + IDA_BUG_ON(ida, ida_find_first_range(ida, (1 << 20), INT_MAX) != -ENOENT); + + ida_free(ida, 3); + ida_free(ida, 63); + ida_free(ida, 1023); + ida_free(ida, (1 << 20) - 1); + + IDA_BUG_ON(ida, !ida_is_empty(ida)); +} + +static DEFINE_IDA(ida); + +static int ida_checks(void) +{ + IDA_BUG_ON(&ida, !ida_is_empty(&ida)); + ida_check_alloc(&ida); + ida_check_destroy(&ida); + ida_check_leaf(&ida, 0); + ida_check_leaf(&ida, 1024); + ida_check_leaf(&ida, 1024 * 64); + ida_check_max(&ida); + ida_check_conv(&ida); + ida_check_bad_free(&ida); + ida_check_find_first(&ida); + + printk("IDA: %u of %u tests passed\n", tests_passed, tests_run); + return (tests_run != tests_passed) ? 0 : -EINVAL; +} + +static void ida_exit(void) +{ +} + +module_init(ida_checks); +module_exit(ida_exit); +MODULE_AUTHOR("Matthew Wilcox "); +MODULE_DESCRIPTION("Test the IDA API"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1