kernel/linux.git/lib/bug.c, branch v6.19.11

bug: avoid format attribute warning for clang as well

2026-04-02T11:25:57+00:00

[ Upstream commit 2598ab9d63f41160c7081998857fef409182933d ] Like gcc, clang-22 now also warns about a function that it incorrectly identifies as a printf-style format: lib/bug.c:190:22: error: diagnostic behavior may be improved by adding the 'format(printf, 1, 0)' attribute to the declaration of '__warn_printf' [-Werror,-Wmissing-format-attribute] 179 | static void __warn_printf(const char *fmt, struct pt_regs *regs) | __attribute__((format(printf, 1, 0))) 180 | { 181 | if (!fmt) 182 | return; 183 | 184 | #ifdef HAVE_ARCH_BUG_FORMAT_ARGS 185 | if (regs) { 186 | struct arch_va_list _args; 187 | va_list *args = __warn_args(&_args, regs); 188 | 189 | if (args) { 190 | vprintk(fmt, *args); | ^ Revert the change that added a gcc-specific workaround, and instead add the generic annotation that avoid the warning. Link: https://lkml.kernel.org/r/20260323205534.1284284-1-arnd@kernel.org Fixes: d36067d6ea00 ("bug: Hush suggest-attribute=format for __warn_printf()") Suggested-by: Andy Shevchenko Suggested-by: Brendan Jackman Link: https://lore.kernel.org/all/20251208141618.2805983-1-andriy.shevchenko@linux.intel.com/T/#u Signed-off-by: Arnd Bergmann Reviewed-by: Brendan Jackman Reviewed-by: Andy Shevchenko Cc: Bill Wendling Cc: Ingo Molnar Cc: Justin Stitt Cc: Nathan Chancellor Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

bug: Hush suggest-attribute=format for __warn_printf()

2025-12-12T09:26:26+00:00

Recent additions to this function cause GCC 14.3.0 to get excited (W=1) and suggest a missing attribute: lib/bug.c: In function '__warn_printf': lib/bug.c:187:25: error: function '__warn_printf' be a candidate for 'gnu_printf' format attribute [-Werror=suggest-attribute=format] 187 | vprintk(fmt, *args); | ^~~~~~~ Disable the diagnostic locally, following the pattern used for stuff like va_format(). Fixes: 5c47b7f3d1a9 ("bug: Add BUG_FORMAT_ARGS infrastructure") Signed-off-by: Brendan Jackman Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://patch.msgid.link/20251207-warn-printf-gcc-v1-1-b597d612b94b@google.com

bug: Let report_bug_entry() provide the correct bugaddr

2025-12-12T09:26:13+00:00

report_bug_entry() always provides zero for bugaddr but could easily extract the correct address from the provided bug_entry. Just do that to have proper warning messages. E.g. adding an artificial: void foo(void) { WARN_ONCE(1, "bar"); } function generates this warning message: WARNING: arch/s390/kernel/setup.c:1017 at 0x0, CPU#0: swapper/0/0 ^^^ With the correct bug address this changes to: WARNING: arch/s390/kernel/setup.c:1017 at foo+0x1c/0x40, CPU#0: swapper/0/0 ^^^^^^^^^^^^^ Fixes: 7d2c27a0ec5e ("bug: Add report_bug_entry()") Signed-off-by: Heiko Carstens Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://patch.msgid.link/20251208200658.3431511-1-hca@linux.ibm.com

x86/bug: Fix BUG_FORMAT vs KASLR

2025-11-27T08:32:47+00:00

Encoding a relative NULL pointer doesn't work for KASLR, when the whole kernel image gets shifted, the __bug_table and the target string get shifted by the same amount and the relative offset is preserved. However when the target is an absolute 0 value and the __bug_table gets moved about, the end result in a pointer equivalent to kaslr_offset(), not NULL. Notably, this will generate SHN_UNDEF relocations, and Ard would really like to not have those at all. Use the empty string to denote no-string. Suggested-by: Linus Torvalds Cc: Ard Biesheuvel Signed-off-by: Peter Zijlstra (Intel)

bug: Add report_bug_entry()

2025-11-21T10:21:31+00:00

Add a report_bug() variant where the bug_entry is already known. This is useful when the exception instruction is not instantiated per-site. But instead has a single instance. In such a case the bug_entry address might be passed along in a known register or something. Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20251110115757.575795595@infradead.org

bug: Add BUG_FORMAT_ARGS infrastructure

2025-11-21T10:21:31+00:00

Add BUG_FORMAT_ARGS; when an architecture is able to provide a va_list given pt_regs, use this to print format arguments. Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20251110115757.457339417@infradead.org

bug: Add BUG_FORMAT infrastructure

2025-11-21T10:21:30+00:00

Add BUG_FORMAT; an architecture opt-in feature that allows adding the WARN_printf() format string to the bug_entry table. Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20251110115757.223371452@infradead.org

bug: Use RCU instead RCU-sched to protect module_bug_list.

2025-03-10T10:54:46+00:00

The list module_bug_list relies on module_mutex for writer synchronisation. The list is already RCU style. The list removal is synchronized with modules' synchronize_rcu() in free_module(). Use RCU read lock protection instead of RCU-sched. Cc: Andrew Morton Signed-off-by: Sebastian Andrzej Siewior Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250108090457.512198-29-bigeasy@linutronix.de Signed-off-by: Petr Pavlu

cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG

2023-01-31T14:01:45+00:00

In order to avoid WARN/BUG from generating nested or even recursive warnings, force rcu_is_watching() true during WARN/lockdep_rcu_suspicious(). Notably things like unwinding the stack can trigger rcu_dereference() warnings, which then triggers more unwinding which then triggers more warnings etc.. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230126151323.408156109@infradead.org

bug: Use normal relative pointers in 'struct bug_entry'

2022-05-19T21:46:10+00:00

With CONFIG_GENERIC_BUG_RELATIVE_POINTERS, the addr/file relative pointers are calculated weirdly: based on the beginning of the bug_entry struct address, rather than their respective pointer addresses. Make the relative pointers less surprising to both humans and tools by calculating them the normal way. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Mark Rutland Acked-by: Peter Zijlstra (Intel) Acked-by: Sven Schnelle # s390 Acked-by: Michael Ellerman (powerpc) Acked-by: Catalin Marinas Tested-by: Mark Rutland [arm64] Link: https://lkml.kernel.org/r/f0e05be797a16f4fc2401eeb88c8450dcbe61df6.1652362951.git.jpoimboe@kernel.org