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[213.113.33.115]) by smtp.gmail.com with ESMTPSA id z195-v6sm4125930lff.82.2018.10.31.05.14.01 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 31 Oct 2018 05:14:02 -0700 (PDT) From: Anders Roxell To: will.deacon@arm.com, jason.wessel@windriver.com, daniel.thompson@linaro.org, james.morse@arm.com Cc: kgdb-bugreport@lists.sourceforge.net, linux-kernel@vger.kernel.org, arnd@arndb.de, Anders Roxell Subject: [RFC PATCH] arm64/mm: hit DEBUG_LOCKS_WARN_ON Date: Wed, 31 Oct 2018 13:13:56 +0100 Message-Id: <20181031121356.30654-1-anders.roxell@linaro.org> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I'm running an arm64 kernel in a qemu guest and I hit this DEBUG_LOCKS_WARN_ON and this patch removes the warning. The interrupts_enabled(reqs) should reflect the irq->enabled state of the kgdb test process when it hit the breakpoint, and that should be the same as the current->hardirqs_enabled flag [ 25.682116] kgdbts:RUN singlestep test 1000 iterations [ 25.695926] ------------[ cut here ]------------ [ 25.696410] DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) [ 25.697407] WARNING: CPU: 0 PID: 1 at ../kernel/locking/lockdep.c:3761 check_flags+0x64/0x198 [ 25.698349] Modules linked in: [ 25.699144] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G T 4.19.0-next-20181030+ #6 [ 25.699739] Hardware name: linux,dummy-virt (DT) [ 25.700359] pstate: 404003c5 (nZcv DAIF +PAN -UAO) [ 25.700901] pc : check_flags+0x64/0x198 [ 25.701381] lr : check_flags+0x64/0x198 [ 25.701779] sp : ffffff800814b800 [ 25.702160] x29: ffffff800814b800 x28: ffffffc03ffbc000 [ 25.702721] x27: ffffff80081ee4d0 x26: 0000000000000000 [ 25.703240] x25: 0000000000000000 x24: 0000000000000002 [ 25.703753] x23: 0000000000000000 x22: 0000000000000000 [ 25.704276] x21: ffffff800aa23000 x20: 00000000000003c0 [ 25.704792] x19: ffffff8009c14000 x18: 00000000ffffffff [ 25.705315] x17: 0000000000000000 x16: 0000000000000000 [ 25.705833] x15: 1740000000000000 x14: 2f6f69747269762f [ 25.706356] x13: ffffffffffff0000 x12: ffffffffffffffff [ 25.706877] x11: 000000000000000e x10: 7f7f7f7f7f7f7f7f [ 25.707431] x9 : ffffff800814b800 x8 : 7261683e2d746e65 [ 25.707954] x7 : 72727563284e4f5f x6 : ffffff800aa2283e [ 25.708471] x5 : 0000000000000000 x4 : 0000000000000000 [ 25.708990] x3 : ffffff8008318584 x2 : ffffffc03ffbc000 [ 25.709512] x1 : 0344ea595a8c0b00 x0 : 0000000000000000 [ 25.710104] Call trace: [ 25.710553] check_flags+0x64/0x198 [ 25.711023] lock_acquire+0x60/0x248 [ 25.711477] call_step_hook+0x5c/0x190 [ 25.711937] single_step_handler+0x48/0xa0 [ 25.712399] do_debug_exception+0x104/0x160 [ 25.712846] el1_dbg+0x18/0xa8 [ 25.713252] el1_irq+0xa8/0x1c0 [ 25.713709] kgdbts_break_test+0x0/0x40 [ 25.714171] kgdbts_run_tests+0x2b0/0x430 [ 25.714637] configure_kgdbts+0x7c/0xb0 [ 25.715110] init_kgdbts+0x70/0xac [ 25.715551] do_one_initcall+0x1fc/0x490 [ 25.716010] do_initcall_level+0x458/0x49c [ 25.716462] do_initcalls+0x60/0xa4 [ 25.716892] do_basic_setup+0x3c/0x68 [ 25.717343] kernel_init_freeable+0x170/0x2b8 [ 25.717860] kernel_init+0x20/0x130 [ 25.718302] ret_from_fork+0x10/0x18 [ 25.718712] irq event stamp: 266621 [ 25.719209] hardirqs last enabled at (266621): [] do_debug_exception+0x13c/0x160 [ 25.719949] hardirqs last disabled at (266620): [] kgdb_roundup_cpus+0x30/0x38 [ 25.720675] softirqs last enabled at (266616): [] __do_softirq+0x4e4/0x52c [ 25.721374] softirqs last disabled at (266609): [] irq_exit+0xbc/0x128 [ 25.722050] ---[ end trace ecb2b85abf3c30a2 ]--- [ 25.722537] possible reason: unannotated irqs-off. [ 25.722960] irq event stamp: 266621 Rework code to drop the 'if (interrupts_enabled(regs))' before trace_hardirqs_*() in function do_debug_exception(). We don't know why current->hardirqs_enabled and interrupts_enabled(regs) don't match. Fixes: 6afedcd23cfd ("arm64: mm: Add trace_irqflags annotations to do_debug_exception()") Signed-off-by: Anders Roxell --- arch/arm64/mm/fault.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 7d9571f4ae3d..9afe5a7ba55b 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -819,11 +819,9 @@ asmlinkage int __exception do_debug_exception(unsigned long addr, int rv; /* - * Tell lockdep we disabled irqs in entry.S. Do nothing if they were - * already disabled to preserve the last enabled/disabled addresses. + * Tell lockdep we disabled irqs in entry.S. */ - if (interrupts_enabled(regs)) - trace_hardirqs_off(); + trace_hardirqs_off(); if (user_mode(regs) && instruction_pointer(regs) > TASK_SIZE) arm64_apply_bp_hardening(); @@ -836,8 +834,7 @@ asmlinkage int __exception do_debug_exception(unsigned long addr, rv = 0; } - if (interrupts_enabled(regs)) - trace_hardirqs_on(); + trace_hardirqs_on(); return rv; } -- 2.19.1