From 398f74569cebbf06bc6b069442bcd0e9616ca465 Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Fri, 19 Jun 2015 21:37:56 +0100 Subject: ARM: 8393/1: smp: Fix suspicious RCU usage with ipi tracepoints John Stultz reports an RCU splat on boot with ARM ipi trace events enabled. =============================== [ INFO: suspicious RCU usage. ] 4.1.0-rc7-00033-gb5bed2f #153 Not tainted ------------------------------- include/trace/events/ipi.h:68 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! no locks held by swapper/0/0. stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.1.0-rc7-00033-gb5bed2f #153 Hardware name: Qualcomm (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0x70/0xbc) [] (dump_stack) from [] (handle_IPI+0x428/0x604) [] (handle_IPI) from [] (gic_handle_irq+0x54/0x5c) [] (gic_handle_irq) from [] (__irq_svc+0x44/0x7c) Exception stack(0xc09f3f48 to 0xc09f3f90) 3f40: 00000001 00000001 00000000 c09f73b8 c09f4528 c0a5de9c 3f60: c076b4f0 00000000 00000000 c09ef108 c0a5cec1 00000001 00000000 c09f3f90 3f80: c026bf60 c0210ab8 20000113 ffffffff [] (__irq_svc) from [] (arch_cpu_idle+0x20/0x3c) [] (arch_cpu_idle) from [] (cpu_startup_entry+0x2c0/0x5dc) [] (cpu_startup_entry) from [] (start_kernel+0x358/0x3c4) [] (start_kernel) from [<8020807c>] (0x8020807c) At this point in the IPI handling path we haven't called irq_enter() yet, so RCU doesn't know that we're about to exit idle and properly warns that we're using RCU from an idle CPU. Use trace_ipi_entry_rcuidle() instead of trace_ipi_entry() so that RCU is informed about our exit from idle. Fixes: 365ec7b17327 ("ARM: add IPI tracepoints") Reported-by: John Stultz Tested-by: John Stultz Acked-by: Steven Rostedt Reviewed-by: Paul E. McKenney Signed-off-by: Stephen Boyd Signed-off-by: Russell King --- arch/arm/kernel/smp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/arm/kernel') diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index cca5b8758185..f11d82527076 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -576,7 +576,7 @@ void handle_IPI(int ipinr, struct pt_regs *regs) struct pt_regs *old_regs = set_irq_regs(regs); if ((unsigned)ipinr < NR_IPI) { - trace_ipi_entry(ipi_types[ipinr]); + trace_ipi_entry_rcuidle(ipi_types[ipinr]); __inc_irq_stat(cpu, ipi_irqs[ipinr]); } @@ -635,7 +635,7 @@ void handle_IPI(int ipinr, struct pt_regs *regs) } if ((unsigned)ipinr < NR_IPI) - trace_ipi_exit(ipi_types[ipinr]); + trace_ipi_exit_rcuidle(ipi_types[ipinr]); set_irq_regs(old_regs); } -- cgit v1.2.3 From 11b8b25ce4f8acfd3b438683c0c9ade27756c6e8 Mon Sep 17 00:00:00 2001 From: Russell King Date: Fri, 3 Jul 2015 12:42:36 +0100 Subject: ARM: fix lockdep unannotated irqs-off warning Wolfram Sang reported an unannotated irqs-off warning from lockdep: WARNING: CPU: 0 PID: 282 at kernel/locking/lockdep.c:3557 check_flags+0x84/0x1f4() DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) CPU: 0 PID: 282 Comm: rcS Tainted: G W 4.1.0-00002-g5b076054611833 #179 Hardware name: Generic Emma Mobile EV2 (Flattened Device Tree) Backtrace: [] (dump_backtrace) from [] (show_stack+0x18/0x1c) r6:c02dcc67 r5:00000009 r4:00000000 r3:00400000 [] (show_stack) from [] (dump_stack+0x20/0x28) [] (dump_stack) from [] (warn_slowpath_common+0x8c/0xb4) [] (warn_slowpath_common) from [] (warn_slowpath_fmt+0x38/0x40) r8:c780f470 r7:00000000 r6:00000000 r5:c03b0570 r4:c0b7ec04 [] (warn_slowpath_fmt) from [] (check_flags+0x84/0x1f4) r3:c02e13d8 r2:c02dceaa [] (check_flags) from [] (lock_acquire+0x4c/0xbc) r5:00000000 r4:60000193 [] (lock_acquire) from [] (_raw_spin_lock+0x34/0x44) r9:000a8d5c r8:00000001 r7:c7806000 r6:c780f460 r5:c03b06a0 r4:c780f460 [] (_raw_spin_lock) from [] (handle_fasteoi_irq+0x20/0x11c) r4:c780f400 [] (handle_fasteoi_irq) from [] (generic_handle_irq+0x28/0x38) r6:00000000 r5:c03b038c r4:00000012 r3:c005a8ac [] (generic_handle_irq) from [] (__handle_domain_irq+0x88/0xa8) r4:00000000 r3:00000026 [] (__handle_domain_irq) from [] (gic_handle_irq+0x40/0x58) r8:10c5347d r7:10c5347d r6:c35b1fb0 r5:c03a6304 r4:c8802000 r3:c35b1fb0 [] (gic_handle_irq) from [] (__irq_usr+0x48/0x60) Exception stack(0xc35b1fb0 to 0xc35b1ff8) 1fa0: 00000061 00000000 000ab736 00000066 1fc0: 00000061 000aa1f0 000a8d54 000a8d54 000a8d88 000a8d5c 000a8cc8 000a8d68 1fe0: 72727272 bef8a528 000398c0 00031334 20000010 ffffffff r6:ffffffff r5:20000010 r4:00031334 r3:00000061 ---[ end trace cb88537fdc8fa202 ]--- possible reason: unannotated irqs-off. irq event stamp: 769 hardirqs last enabled at (769): [] ret_fast_syscall+0x2c/0x54 hardirqs last disabled at (768): [] ret_fast_syscall+0xc/0x54 softirqs last enabled at (0): [] copy_process.part.65+0x2e8/0x11dc softirqs last disabled at (0): [< (null)>] (null) His kernel configuration had: CONFIG_PROVE_LOCKING=y CONFIG_TRACE_IRQFLAGS=y but no IRQSOFF_TRACER, which means entry from userspace can result in the kernel seeing IRQs off without being notified of that change of state. Change the IRQSOFF ifdef in the usr_entry macro to TRACE_IRQFLAGS instead. Tested-by: Wolfram Sang Signed-off-by: Russell King --- arch/arm/kernel/entry-armv.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/arm/kernel') diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index 570306c49406..dba6cf65c9e4 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -408,7 +408,7 @@ ENDPROC(__fiq_abt) zero_fp .if \trace -#ifdef CONFIG_IRQSOFF_TRACER +#ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_off #endif ct_user_exit save = 0 -- cgit v1.2.3 From 1bd46782d08b01b73df0085b51ea1021b19b44fd Mon Sep 17 00:00:00 2001 From: Russell King Date: Fri, 3 Jul 2015 15:22:54 +0100 Subject: ARM: avoid unwanted GCC memset()/memcpy() optimisations for IO variants We don't want GCC optimising our memset_io(), memcpy_fromio() or memcpy_toio() variants, so we must not call one of the standard functions. Provide a separate name for our assembly memcpy() and memset() functions, and use that instead, thereby bypassing GCC's ability to optimise these operations. GCCs optimisation may introduce unaligned accesses which are invalid for device mappings. Signed-off-by: Russell King --- arch/arm/include/asm/io.h | 9 ++++++--- arch/arm/kernel/armksyms.c | 6 ++++++ arch/arm/lib/memcpy.S | 2 ++ arch/arm/lib/memset.S | 2 ++ 4 files changed, 16 insertions(+), 3 deletions(-) (limited to 'arch/arm/kernel') diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index a5ed237c87d9..485982084fe9 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -316,21 +316,24 @@ extern void _memset_io(volatile void __iomem *, int, size_t); static inline void memset_io(volatile void __iomem *dst, unsigned c, size_t count) { - memset((void __force *)dst, c, count); + extern void mmioset(void *, unsigned int, size_t); + mmioset((void __force *)dst, c, count); } #define memset_io(dst,c,count) memset_io(dst,c,count) static inline void memcpy_fromio(void *to, const volatile void __iomem *from, size_t count) { - memcpy(to, (const void __force *)from, count); + extern void mmiocpy(void *, const void *, size_t); + mmiocpy(to, (const void __force *)from, count); } #define memcpy_fromio(to,from,count) memcpy_fromio(to,from,count) static inline void memcpy_toio(volatile void __iomem *to, const void *from, size_t count) { - memcpy((void __force *)to, from, count); + extern void mmiocpy(void *, const void *, size_t); + mmiocpy((void __force *)to, from, count); } #define memcpy_toio(to,from,count) memcpy_toio(to,from,count) diff --git a/arch/arm/kernel/armksyms.c b/arch/arm/kernel/armksyms.c index a88671cfe1ff..5e5a51a99e68 100644 --- a/arch/arm/kernel/armksyms.c +++ b/arch/arm/kernel/armksyms.c @@ -50,6 +50,9 @@ extern void __aeabi_ulcmp(void); extern void fpundefinstr(void); +void mmioset(void *, unsigned int, size_t); +void mmiocpy(void *, const void *, size_t); + /* platform dependent support */ EXPORT_SYMBOL(arm_delay_ops); @@ -88,6 +91,9 @@ EXPORT_SYMBOL(memmove); EXPORT_SYMBOL(memchr); EXPORT_SYMBOL(__memzero); +EXPORT_SYMBOL(mmioset); +EXPORT_SYMBOL(mmiocpy); + #ifdef CONFIG_MMU EXPORT_SYMBOL(copy_page); diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S index 7797e81e40e0..64111bd4440b 100644 --- a/arch/arm/lib/memcpy.S +++ b/arch/arm/lib/memcpy.S @@ -61,8 +61,10 @@ /* Prototype: void *memcpy(void *dest, const void *src, size_t n); */ +ENTRY(mmiocpy) ENTRY(memcpy) #include "copy_template.S" ENDPROC(memcpy) +ENDPROC(mmiocpy) diff --git a/arch/arm/lib/memset.S b/arch/arm/lib/memset.S index a4ee97b5a2bf..3c65e3bd790f 100644 --- a/arch/arm/lib/memset.S +++ b/arch/arm/lib/memset.S @@ -16,6 +16,7 @@ .text .align 5 +ENTRY(mmioset) ENTRY(memset) UNWIND( .fnstart ) ands r3, r0, #3 @ 1 unaligned? @@ -133,3 +134,4 @@ UNWIND( .fnstart ) b 1b UNWIND( .fnend ) ENDPROC(memset) +ENDPROC(mmioset) -- cgit v1.2.3