| Message ID | 20220213081845.9864-1-changbin.du@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4] riscv: fix oops caused by irqsoff latency tracer | expand |
hello, kindly ping for review status. :) On Sun, Feb 13, 2022 at 04:18:45PM +0800, Changbin Du wrote: > The trace_hardirqs_{on,off}() require the caller to setup frame pointer > properly. This because these two functions use macro 'CALLER_ADDR1' (aka. > __builtin_return_address(1)) to acquire caller info. If the $fp is used > for other purpose, the code generated this macro (as below) could trigger > memory access fault. > > 0xffffffff8011510e <+80>: ld a1,-16(s0) > 0xffffffff80115112 <+84>: ld s2,-8(a1) # <-- paging fault here > > The oops message during booting if compiled with 'irqoff' tracer enabled: > [ 0.039615][ T0] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000f8 > [ 0.041925][ T0] Oops [#1] > [ 0.042063][ T0] Modules linked in: > [ 0.042864][ T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.17.0-rc1-00233-g9a20c48d1ed2 #29 > [ 0.043568][ T0] Hardware name: riscv-virtio,qemu (DT) > [ 0.044343][ T0] epc : trace_hardirqs_on+0x56/0xe2 > [ 0.044601][ T0] ra : restore_all+0x12/0x6e > [ 0.044721][ T0] epc : ffffffff80126a5c ra : ffffffff80003b94 sp : ffffffff81403db0 > [ 0.044801][ T0] gp : ffffffff8163acd8 tp : ffffffff81414880 t0 : 0000000000000020 > [ 0.044882][ T0] t1 : 0098968000000000 t2 : 0000000000000000 s0 : ffffffff81403de0 > [ 0.044967][ T0] s1 : 0000000000000000 a0 : 0000000000000001 a1 : 0000000000000100 > [ 0.045046][ T0] a2 : 0000000000000000 a3 : 0000000000000000 a4 : 0000000000000000 > [ 0.045124][ T0] a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000054494d45 > [ 0.045210][ T0] s2 : ffffffff80003b94 s3 : ffffffff81a8f1b0 s4 : ffffffff80e27b50 > [ 0.045289][ T0] s5 : ffffffff81414880 s6 : ffffffff8160fa00 s7 : 00000000800120e8 > [ 0.045389][ T0] s8 : 0000000080013100 s9 : 000000000000007f s10: 0000000000000000 > [ 0.045474][ T0] s11: 0000000000000000 t3 : 7fffffffffffffff t4 : 0000000000000000 > [ 0.045548][ T0] t5 : 0000000000000000 t6 : ffffffff814aa368 > [ 0.045620][ T0] status: 0000000200000100 badaddr: 00000000000000f8 cause: 000000000000000d > [ 0.046402][ T0] [<ffffffff80003b94>] restore_all+0x12/0x6e > > This because the $fp(aka. $s0) register is not used as frame pointer in the > assembly entry code. > > resume_kernel: > REG_L s0, TASK_TI_PREEMPT_COUNT(tp) > bnez s0, restore_all > REG_L s0, TASK_TI_FLAGS(tp) > andi s0, s0, _TIF_NEED_RESCHED > beqz s0, restore_all > call preempt_schedule_irq > j restore_all > > To fix above issue, here we add one extra level wrapper for function > trace_hardirqs_{on,off}() so they can be safely called by low level entry > code. > > Signed-off-by: Changbin Du <changbin.du@gmail.com> > > --- > v4: update explanation. > v3: fix warning reported by documentation system. > v2: fix compile warning. > --- > arch/riscv/kernel/Makefile | 2 ++ > arch/riscv/kernel/entry.S | 10 +++++----- > arch/riscv/kernel/trace_irq.c | 27 +++++++++++++++++++++++++++ > arch/riscv/kernel/trace_irq.h | 11 +++++++++++ > 4 files changed, 45 insertions(+), 5 deletions(-) > create mode 100644 arch/riscv/kernel/trace_irq.c > create mode 100644 arch/riscv/kernel/trace_irq.h > > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile > index 612556faa527..ffc87e76b1dd 100644 > --- a/arch/riscv/kernel/Makefile > +++ b/arch/riscv/kernel/Makefile > @@ -51,6 +51,8 @@ obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o > obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o > obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o > > +obj-$(CONFIG_TRACE_IRQFLAGS) += trace_irq.o > + > obj-$(CONFIG_RISCV_BASE_PMU) += perf_event.o > obj-$(CONFIG_PERF_EVENTS) += perf_callchain.o > obj-$(CONFIG_HAVE_PERF_REGS) += perf_regs.o > diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S > index ed29e9c8f660..d6a46ed0bf05 100644 > --- a/arch/riscv/kernel/entry.S > +++ b/arch/riscv/kernel/entry.S > @@ -108,7 +108,7 @@ _save_context: > .option pop > > #ifdef CONFIG_TRACE_IRQFLAGS > - call trace_hardirqs_off > + call __trace_hardirqs_off > #endif > > #ifdef CONFIG_CONTEXT_TRACKING > @@ -143,7 +143,7 @@ skip_context_tracking: > li t0, EXC_BREAKPOINT > beq s4, t0, 1f > #ifdef CONFIG_TRACE_IRQFLAGS > - call trace_hardirqs_on > + call __trace_hardirqs_on > #endif > csrs CSR_STATUS, SR_IE > > @@ -234,7 +234,7 @@ ret_from_exception: > REG_L s0, PT_STATUS(sp) > csrc CSR_STATUS, SR_IE > #ifdef CONFIG_TRACE_IRQFLAGS > - call trace_hardirqs_off > + call __trace_hardirqs_off > #endif > #ifdef CONFIG_RISCV_M_MODE > /* the MPP value is too large to be used as an immediate arg for addi */ > @@ -270,10 +270,10 @@ restore_all: > REG_L s1, PT_STATUS(sp) > andi t0, s1, SR_PIE > beqz t0, 1f > - call trace_hardirqs_on > + call __trace_hardirqs_on > j 2f > 1: > - call trace_hardirqs_off > + call __trace_hardirqs_off > 2: > #endif > REG_L a0, PT_STATUS(sp) > diff --git a/arch/riscv/kernel/trace_irq.c b/arch/riscv/kernel/trace_irq.c > new file mode 100644 > index 000000000000..095ac976d7da > --- /dev/null > +++ b/arch/riscv/kernel/trace_irq.c > @@ -0,0 +1,27 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2022 Changbin Du <changbin.du@gmail.com> > + */ > + > +#include <linux/irqflags.h> > +#include <linux/kprobes.h> > +#include "trace_irq.h" > + > +/* > + * trace_hardirqs_on/off require the caller to setup frame pointer properly. > + * Otherwise, CALLER_ADDR1 might trigger an pagging exception in kernel. > + * Here we add one extra level so they can be safely called by low > + * level entry code which $fp is used for other purpose. > + */ > + > +void __trace_hardirqs_on(void) > +{ > + trace_hardirqs_on(); > +} > +NOKPROBE_SYMBOL(__trace_hardirqs_on); > + > +void __trace_hardirqs_off(void) > +{ > + trace_hardirqs_off(); > +} > +NOKPROBE_SYMBOL(__trace_hardirqs_off); > diff --git a/arch/riscv/kernel/trace_irq.h b/arch/riscv/kernel/trace_irq.h > new file mode 100644 > index 000000000000..99fe67377e5e > --- /dev/null > +++ b/arch/riscv/kernel/trace_irq.h > @@ -0,0 +1,11 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright (C) 2022 Changbin Du <changbin.du@gmail.com> > + */ > +#ifndef __TRACE_IRQ_H > +#define __TRACE_IRQ_H > + > +void __trace_hardirqs_on(void); > +void __trace_hardirqs_off(void); > + > +#endif /* __TRACE_IRQ_H */ > -- > 2.32.0 >
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 612556faa527..ffc87e76b1dd 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -51,6 +51,8 @@ obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o +obj-$(CONFIG_TRACE_IRQFLAGS) += trace_irq.o + obj-$(CONFIG_RISCV_BASE_PMU) += perf_event.o obj-$(CONFIG_PERF_EVENTS) += perf_callchain.o obj-$(CONFIG_HAVE_PERF_REGS) += perf_regs.o diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index ed29e9c8f660..d6a46ed0bf05 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -108,7 +108,7 @@ _save_context: .option pop #ifdef CONFIG_TRACE_IRQFLAGS - call trace_hardirqs_off + call __trace_hardirqs_off #endif #ifdef CONFIG_CONTEXT_TRACKING @@ -143,7 +143,7 @@ skip_context_tracking: li t0, EXC_BREAKPOINT beq s4, t0, 1f #ifdef CONFIG_TRACE_IRQFLAGS - call trace_hardirqs_on + call __trace_hardirqs_on #endif csrs CSR_STATUS, SR_IE @@ -234,7 +234,7 @@ ret_from_exception: REG_L s0, PT_STATUS(sp) csrc CSR_STATUS, SR_IE #ifdef CONFIG_TRACE_IRQFLAGS - call trace_hardirqs_off + call __trace_hardirqs_off #endif #ifdef CONFIG_RISCV_M_MODE /* the MPP value is too large to be used as an immediate arg for addi */ @@ -270,10 +270,10 @@ restore_all: REG_L s1, PT_STATUS(sp) andi t0, s1, SR_PIE beqz t0, 1f - call trace_hardirqs_on + call __trace_hardirqs_on j 2f 1: - call trace_hardirqs_off + call __trace_hardirqs_off 2: #endif REG_L a0, PT_STATUS(sp) diff --git a/arch/riscv/kernel/trace_irq.c b/arch/riscv/kernel/trace_irq.c new file mode 100644 index 000000000000..095ac976d7da --- /dev/null +++ b/arch/riscv/kernel/trace_irq.c @@ -0,0 +1,27 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2022 Changbin Du <changbin.du@gmail.com> + */ + +#include <linux/irqflags.h> +#include <linux/kprobes.h> +#include "trace_irq.h" + +/* + * trace_hardirqs_on/off require the caller to setup frame pointer properly. + * Otherwise, CALLER_ADDR1 might trigger an pagging exception in kernel. + * Here we add one extra level so they can be safely called by low + * level entry code which $fp is used for other purpose. + */ + +void __trace_hardirqs_on(void) +{ + trace_hardirqs_on(); +} +NOKPROBE_SYMBOL(__trace_hardirqs_on); + +void __trace_hardirqs_off(void) +{ + trace_hardirqs_off(); +} +NOKPROBE_SYMBOL(__trace_hardirqs_off); diff --git a/arch/riscv/kernel/trace_irq.h b/arch/riscv/kernel/trace_irq.h new file mode 100644 index 000000000000..99fe67377e5e --- /dev/null +++ b/arch/riscv/kernel/trace_irq.h @@ -0,0 +1,11 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2022 Changbin Du <changbin.du@gmail.com> + */ +#ifndef __TRACE_IRQ_H +#define __TRACE_IRQ_H + +void __trace_hardirqs_on(void); +void __trace_hardirqs_off(void); + +#endif /* __TRACE_IRQ_H */
The trace_hardirqs_{on,off}() require the caller to setup frame pointer properly. This because these two functions use macro 'CALLER_ADDR1' (aka. __builtin_return_address(1)) to acquire caller info. If the $fp is used for other purpose, the code generated this macro (as below) could trigger memory access fault. 0xffffffff8011510e <+80>: ld a1,-16(s0) 0xffffffff80115112 <+84>: ld s2,-8(a1) # <-- paging fault here The oops message during booting if compiled with 'irqoff' tracer enabled: [ 0.039615][ T0] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000f8 [ 0.041925][ T0] Oops [#1] [ 0.042063][ T0] Modules linked in: [ 0.042864][ T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.17.0-rc1-00233-g9a20c48d1ed2 #29 [ 0.043568][ T0] Hardware name: riscv-virtio,qemu (DT) [ 0.044343][ T0] epc : trace_hardirqs_on+0x56/0xe2 [ 0.044601][ T0] ra : restore_all+0x12/0x6e [ 0.044721][ T0] epc : ffffffff80126a5c ra : ffffffff80003b94 sp : ffffffff81403db0 [ 0.044801][ T0] gp : ffffffff8163acd8 tp : ffffffff81414880 t0 : 0000000000000020 [ 0.044882][ T0] t1 : 0098968000000000 t2 : 0000000000000000 s0 : ffffffff81403de0 [ 0.044967][ T0] s1 : 0000000000000000 a0 : 0000000000000001 a1 : 0000000000000100 [ 0.045046][ T0] a2 : 0000000000000000 a3 : 0000000000000000 a4 : 0000000000000000 [ 0.045124][ T0] a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000054494d45 [ 0.045210][ T0] s2 : ffffffff80003b94 s3 : ffffffff81a8f1b0 s4 : ffffffff80e27b50 [ 0.045289][ T0] s5 : ffffffff81414880 s6 : ffffffff8160fa00 s7 : 00000000800120e8 [ 0.045389][ T0] s8 : 0000000080013100 s9 : 000000000000007f s10: 0000000000000000 [ 0.045474][ T0] s11: 0000000000000000 t3 : 7fffffffffffffff t4 : 0000000000000000 [ 0.045548][ T0] t5 : 0000000000000000 t6 : ffffffff814aa368 [ 0.045620][ T0] status: 0000000200000100 badaddr: 00000000000000f8 cause: 000000000000000d [ 0.046402][ T0] [<ffffffff80003b94>] restore_all+0x12/0x6e This because the $fp(aka. $s0) register is not used as frame pointer in the assembly entry code. resume_kernel: REG_L s0, TASK_TI_PREEMPT_COUNT(tp) bnez s0, restore_all REG_L s0, TASK_TI_FLAGS(tp) andi s0, s0, _TIF_NEED_RESCHED beqz s0, restore_all call preempt_schedule_irq j restore_all To fix above issue, here we add one extra level wrapper for function trace_hardirqs_{on,off}() so they can be safely called by low level entry code. Signed-off-by: Changbin Du <changbin.du@gmail.com> --- v4: update explanation. v3: fix warning reported by documentation system. v2: fix compile warning. --- arch/riscv/kernel/Makefile | 2 ++ arch/riscv/kernel/entry.S | 10 +++++----- arch/riscv/kernel/trace_irq.c | 27 +++++++++++++++++++++++++++ arch/riscv/kernel/trace_irq.h | 11 +++++++++++ 4 files changed, 45 insertions(+), 5 deletions(-) create mode 100644 arch/riscv/kernel/trace_irq.c create mode 100644 arch/riscv/kernel/trace_irq.h