From: Lee Jones <lee.jones@linaro.org> To: "haibinzhang(张海斌)" <haibinzhang@tencent.com> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Ard Biesheuvel <ard.biesheuvel@arm.com>, Martin Ma <Martin.Ma@arm.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "hewenliang4@huawei.com" <hewenliang4@huawei.com> Subject: Re: [PATCH V2] arm64: fix oops in concurrently setting insn_emulation sysctls Date: Wed, 20 Jul 2022 13:23:24 +0100 [thread overview] Message-ID: <YtfzvK0T8pJacsDm@google.com> (raw) In-Reply-To: <9A004C03-250B-46C5-BF39-782D7551B00E@tencent.com> On Sat, 02 Jul 2022, haibinzhang(张海斌) wrote: > How to reproduce: > launch two shell executions: > #!/bin/bash > while [ 1 ]; > do > echo 1 > /proc/sys/abi/swp > done > > Oops info: > Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 > Internal error: Oops: 96000006 [#1] SMP > Call trace: > update_insn_emulation_mode+0xc0/0x148 > emulation_proc_handler+0x64/0xb8 > proc_sys_call_handler+0x9c/0xf8 > proc_sys_write+0x18/0x20 > __vfs_write+0x20/0x48 > vfs_write+0xe4/0x1d0 > ksys_write+0x70/0xf8 > __arm64_sys_write+0x20/0x28 > el0_svc_common.constprop.0+0x7c/0x1c0 > el0_svc_handler+0x2c/0xa0 > el0_svc+0x8/0x200 > > emulation_proc_handler changes table->data for proc_dointvec_minmax > and so it isn't allowed to reenter before restoring table->data, > which isn't right now. > To fix this issue, keep the table->data as &insn->current_mode and > use container_of() to retrieve the insn pointer. Another mutex is > used to protect against the current_mode update but not for retrieving > insn_emulation as table->data is no longer changing. Looks as though this lost its Fixes tag during the rework. Fixes: 587064b610c7 ("arm64: Add framework for legacy instruction emulation") Will, are you able to add this retroactively? > Signed-off-by: hewenliang <hewenliang4@huawei.com> > Signed-off-by: Haibin Zhang <haibinzhang@tencent.com> > --- > arch/arm64/kernel/armv8_deprecated.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c > index 6875a16b09d2..fb0e7c7b2e20 100644 > --- a/arch/arm64/kernel/armv8_deprecated.c > +++ b/arch/arm64/kernel/armv8_deprecated.c > @@ -59,6 +59,7 @@ struct insn_emulation { > static LIST_HEAD(insn_emulation); > static int nr_insn_emulated __initdata; > static DEFINE_RAW_SPINLOCK(insn_emulation_lock); > +static DEFINE_MUTEX(insn_emulation_mutex); > > static void register_emulation_hooks(struct insn_emulation_ops *ops) > { > @@ -207,10 +208,10 @@ static int emulation_proc_handler(struct ctl_table *table, int write, > loff_t *ppos) > { > int ret = 0; > - struct insn_emulation *insn = (struct insn_emulation *) table->data; > + struct insn_emulation *insn = container_of(table->data, struct insn_emulation, current_mode); > enum insn_emulation_mode prev_mode = insn->current_mode; > > - table->data = &insn->current_mode; > + mutex_lock(&insn_emulation_mutex); > ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); > > if (ret || !write || prev_mode == insn->current_mode) > @@ -223,7 +224,7 @@ static int emulation_proc_handler(struct ctl_table *table, int write, > update_insn_emulation_mode(insn, INSN_UNDEF); > } > ret: > - table->data = insn; > + mutex_unlock(&insn_emulation_mutex); > return ret; > } > > @@ -247,7 +248,7 @@ static void __init register_insn_emulation_sysctl(void) > sysctl->maxlen = sizeof(int); > > sysctl->procname = insn->ops->name; > - sysctl->data = insn; > + sysctl->data = &insn->current_mode; > sysctl->extra1 = &insn->min; > sysctl->extra2 = &insn->max; > sysctl->proc_handler = emulation_proc_handler; > -- > 2.34.1 > -- Lee Jones [李琼斯] Principal Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog
WARNING: multiple messages have this Message-ID (diff)
From: Lee Jones <lee.jones@linaro.org> To: "haibinzhang(张海斌)" <haibinzhang@tencent.com> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Ard Biesheuvel <ard.biesheuvel@arm.com>, Martin Ma <Martin.Ma@arm.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "hewenliang4@huawei.com" <hewenliang4@huawei.com> Subject: Re: [PATCH V2] arm64: fix oops in concurrently setting insn_emulation sysctls Date: Wed, 20 Jul 2022 13:23:24 +0100 [thread overview] Message-ID: <YtfzvK0T8pJacsDm@google.com> (raw) In-Reply-To: <9A004C03-250B-46C5-BF39-782D7551B00E@tencent.com> On Sat, 02 Jul 2022, haibinzhang(张海斌) wrote: > How to reproduce: > launch two shell executions: > #!/bin/bash > while [ 1 ]; > do > echo 1 > /proc/sys/abi/swp > done > > Oops info: > Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 > Internal error: Oops: 96000006 [#1] SMP > Call trace: > update_insn_emulation_mode+0xc0/0x148 > emulation_proc_handler+0x64/0xb8 > proc_sys_call_handler+0x9c/0xf8 > proc_sys_write+0x18/0x20 > __vfs_write+0x20/0x48 > vfs_write+0xe4/0x1d0 > ksys_write+0x70/0xf8 > __arm64_sys_write+0x20/0x28 > el0_svc_common.constprop.0+0x7c/0x1c0 > el0_svc_handler+0x2c/0xa0 > el0_svc+0x8/0x200 > > emulation_proc_handler changes table->data for proc_dointvec_minmax > and so it isn't allowed to reenter before restoring table->data, > which isn't right now. > To fix this issue, keep the table->data as &insn->current_mode and > use container_of() to retrieve the insn pointer. Another mutex is > used to protect against the current_mode update but not for retrieving > insn_emulation as table->data is no longer changing. Looks as though this lost its Fixes tag during the rework. Fixes: 587064b610c7 ("arm64: Add framework for legacy instruction emulation") Will, are you able to add this retroactively? > Signed-off-by: hewenliang <hewenliang4@huawei.com> > Signed-off-by: Haibin Zhang <haibinzhang@tencent.com> > --- > arch/arm64/kernel/armv8_deprecated.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c > index 6875a16b09d2..fb0e7c7b2e20 100644 > --- a/arch/arm64/kernel/armv8_deprecated.c > +++ b/arch/arm64/kernel/armv8_deprecated.c > @@ -59,6 +59,7 @@ struct insn_emulation { > static LIST_HEAD(insn_emulation); > static int nr_insn_emulated __initdata; > static DEFINE_RAW_SPINLOCK(insn_emulation_lock); > +static DEFINE_MUTEX(insn_emulation_mutex); > > static void register_emulation_hooks(struct insn_emulation_ops *ops) > { > @@ -207,10 +208,10 @@ static int emulation_proc_handler(struct ctl_table *table, int write, > loff_t *ppos) > { > int ret = 0; > - struct insn_emulation *insn = (struct insn_emulation *) table->data; > + struct insn_emulation *insn = container_of(table->data, struct insn_emulation, current_mode); > enum insn_emulation_mode prev_mode = insn->current_mode; > > - table->data = &insn->current_mode; > + mutex_lock(&insn_emulation_mutex); > ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); > > if (ret || !write || prev_mode == insn->current_mode) > @@ -223,7 +224,7 @@ static int emulation_proc_handler(struct ctl_table *table, int write, > update_insn_emulation_mode(insn, INSN_UNDEF); > } > ret: > - table->data = insn; > + mutex_unlock(&insn_emulation_mutex); > return ret; > } > > @@ -247,7 +248,7 @@ static void __init register_insn_emulation_sysctl(void) > sysctl->maxlen = sizeof(int); > > sysctl->procname = insn->ops->name; > - sysctl->data = insn; > + sysctl->data = &insn->current_mode; > sysctl->extra1 = &insn->min; > sysctl->extra2 = &insn->max; > sysctl->proc_handler = emulation_proc_handler; > -- > 2.34.1 > -- Lee Jones [李琼斯] Principal Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-07-20 12:23 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-07-02 5:43 [PATCH V2] arm64: fix oops in concurrently setting insn_emulation sysctls haibinzhang(张海斌) 2022-07-02 5:43 ` haibinzhang(张海斌) 2022-07-04 10:34 ` Catalin Marinas 2022-07-04 10:34 ` Catalin Marinas 2022-07-04 14:27 ` Will Deacon 2022-07-04 14:27 ` Will Deacon 2022-07-20 12:23 ` Lee Jones [this message] 2022-07-20 12:23 ` Lee Jones 2022-07-20 15:13 ` Will Deacon 2022-07-20 15:13 ` Will Deacon 2022-07-20 15:33 ` Lee Jones 2022-07-20 15:33 ` Lee Jones 2022-07-20 16:11 ` Will Deacon 2022-07-20 16:11 ` Will Deacon
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