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McKenney" , Nathan Chancellor , Nick Desaulniers , llvm@lists.linux.dev, linux-kernel@vger.kernel.org, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org RCU_NONIDLE usage during __cfi_slowpath_diag can result in an invalid RCU state in the cpuidle code path: WARNING: CPU: 1 PID: 0 at kernel/rcu/tree.c:613 rcu_eqs_enter+0xe4/0x138 ... Call trace: rcu_eqs_enter+0xe4/0x138 rcu_idle_enter+0xa8/0x100 cpuidle_enter_state+0x154/0x3a8 cpuidle_enter+0x3c/0x58 do_idle.llvm.6590768638138871020+0x1f4/0x2ec cpu_startup_entry+0x28/0x2c secondary_start_kernel+0x1b8/0x220 __secondary_switched+0x94/0x98 Instead, call rcu_irq_enter/exit to wake up RCU only when needed and disable interrupts for the entire CFI shadow/module check when we do. Signed-off-by: Sami Tolvanen --- kernel/cfi.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/kernel/cfi.c b/kernel/cfi.c index 9594cfd1cf2c..08102d19ec15 100644 --- a/kernel/cfi.c +++ b/kernel/cfi.c @@ -281,6 +281,8 @@ static inline cfi_check_fn find_module_check_fn(unsigned long ptr) static inline cfi_check_fn find_check_fn(unsigned long ptr) { cfi_check_fn fn = NULL; + unsigned long flags; + bool rcu_idle; if (is_kernel_text(ptr)) return __cfi_check; @@ -290,13 +292,21 @@ static inline cfi_check_fn find_check_fn(unsigned long ptr) * the shadow and __module_address use RCU, so we need to wake it * up if necessary. */ - RCU_NONIDLE({ - if (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW)) - fn = find_shadow_check_fn(ptr); + rcu_idle = !rcu_is_watching(); + if (rcu_idle) { + local_irq_save(flags); + rcu_irq_enter(); + } + + if (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW)) + fn = find_shadow_check_fn(ptr); + if (!fn) + fn = find_module_check_fn(ptr); - if (!fn) - fn = find_module_check_fn(ptr); - }); + if (rcu_idle) { + rcu_irq_exit(); + local_irq_restore(flags); + } return fn; } -- 2.36.1.255.ge46751e96f-goog