From: Borislav Petkov <bp@alien8.de>
To: Tony Luck <tony.luck@intel.com>
Cc: Youquan Song <youquan.song@intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 6/7] x86/mce: Recover from poison found while copying from user space
Date: Mon, 5 Oct 2020 18:32:47 +0200 [thread overview]
Message-ID: <20201005163247.GE21151@zn.tnic> (raw)
In-Reply-To: <20200930232611.15355-7-tony.luck@intel.com>
On Wed, Sep 30, 2020 at 04:26:10PM -0700, Tony Luck wrote:
> From: Youquan Song <youquan.song@intel.com>
>
> Existing kernel code can only recover from a machine check on code that
> is tagged in the exception table with a fault handling recovery path.
>
> Two new fields in the task structure to pass information from machine
> check handler to the "task_work" that is queued to run before the task
> returns to user mode:
>
> + mce_vaddr: will be initialized to the user virtual address of the fault
> in the case where the fault occurred in the kernel copying data from
> a user address. This is so that kill_me_maybe() can provide that
> information to the user SIGBUS handler.
>
> + mce_kflags: copy of the struct mce.kflags needed by kill_me_maybe()
> to determine if mce_vaddr is applicable to this error.
>
> Add code to recover from a machine check while copying data from user
> space to the kernel. Action for this case is the same as if the user
> touched the poison directly; unmap the page and send a SIGBUS to the task.
>
> Refactor the recovery code path to share common code between the "fault
> in user mode" case and the "fault while copying from user" case.
>
> New code paths will be activated by the next patch which sets
> MCE_IN_KERNEL_COPYIN.
>
> Signed-off-by: Youquan Song <youquan.song@intel.com>
> Signed-off-by: Tony Luck <tony.luck@intel.com>
> ---
> arch/x86/kernel/cpu/mce/core.c | 33 +++++++++++++++++++++------------
> include/linux/sched.h | 2 ++
> 2 files changed, 23 insertions(+), 12 deletions(-)
Isn't that just simpler?
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 4d2cf08820af..dc6c83aa2ec1 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1261,6 +1261,21 @@ static void kill_me_maybe(struct callback_head *cb)
kill_me_now(cb);
}
+static inline void queue_task_work(struct mce *m, int kill_it)
+{
+ current->mce_addr = m->addr;
+ current->mce_kflags = m->kflags;
+ current->mce_ripv = !!(m->mcgstatus & MCG_STATUS_RIPV);
+ current->mce_whole_page = whole_page(m);
+
+ if (kill_it)
+ current->mce_kill_me.func = kill_me_now;
+ else
+ current->mce_kill_me.func = kill_me_maybe;
+
+ task_work_add(current, ¤t->mce_kill_me, true);
+}
+
/*
* The actual machine check handler. This only handles real
* exceptions when something got corrupted coming in through int 18.
@@ -1402,13 +1417,8 @@ noinstr void do_machine_check(struct pt_regs *regs)
/* If this triggers there is no way to recover. Die hard. */
BUG_ON(!on_thread_stack() || !user_mode(regs));
- current->mce_addr = m.addr;
- current->mce_ripv = !!(m.mcgstatus & MCG_STATUS_RIPV);
- current->mce_whole_page = whole_page(&m);
- current->mce_kill_me.func = kill_me_maybe;
- if (kill_it)
- current->mce_kill_me.func = kill_me_now;
- task_work_add(current, ¤t->mce_kill_me, true);
+ queue_task_work(&m, kill_it);
+
} else {
/*
* Handle an MCE which has happened in kernel space but from
@@ -1423,6 +1433,9 @@ noinstr void do_machine_check(struct pt_regs *regs)
if (!fixup_exception(regs, X86_TRAP_MC, 0, 0))
mce_panic("Failed kernel mode recovery", &m, msg);
}
+
+ if (m.kflags & MCE_IN_KERNEL_COPYIN)
+ queue_task_work(&m, kill_it);
}
out:
mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e7f65573dde3..d383cf09e78f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1308,6 +1308,8 @@ struct task_struct {
#endif
#ifdef CONFIG_X86_MCE
+ void __user *mce_vaddr;
+ __u64 mce_kflags;
u64 mce_addr;
__u64 mce_ripv : 1,
mce_whole_page : 1,
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-10-05 16:32 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200908175519.14223-1-tony.luck@intel.com>
2020-09-08 17:55 ` [PATCH 1/8] x86/mce: Stop mce_reign() from re-computing severity for every CPU Tony Luck
2020-09-14 17:21 ` Borislav Petkov
2020-09-14 17:32 ` [tip: ras/core] " tip-bot2 for Tony Luck
2020-09-08 17:55 ` [PATCH 4/8] x86/mce: Add _ASM_EXTABLE_CPY for copy user access Tony Luck
2020-09-16 9:59 ` Borislav Petkov
2020-09-08 17:55 ` [PATCH 5/8] x86/mce: Avoid tail copy when machine check terminated a copy from user Tony Luck
2020-09-16 10:53 ` Borislav Petkov
2020-09-16 19:26 ` Luck, Tony
2020-09-17 17:04 ` Borislav Petkov
2020-09-17 21:57 ` Luck, Tony
2020-09-18 7:51 ` Borislav Petkov
2020-09-08 17:55 ` [PATCH 6/8] x86/mce: Change fault_in_kernel_space() from static to global Tony Luck
2020-09-08 17:55 ` [PATCH 7/8] x86/mce: Recover from poison found while copying from user space Tony Luck
2020-09-18 16:13 ` Borislav Petkov
2020-09-08 17:55 ` [PATCH 8/8] x86/mce: Decode a kernel instruction to determine if it is copying from user Tony Luck
2020-09-21 11:31 ` Borislav Petkov
2020-09-30 23:26 ` [PATCH v2 0/7] Add machine check recovery when copying from user space Tony Luck
2020-09-30 23:26 ` [PATCH v2 1/7] x86/mce: Pass pointer to saved pt_regs to severity calculation routines Tony Luck
2020-09-30 23:26 ` [PATCH v2 2/7] x86/mce: Provide method to find out the type of exception handle Tony Luck
2020-10-05 16:35 ` Borislav Petkov
2020-09-30 23:26 ` [PATCH v2 3/7] x86/mce: Add _ASM_EXTABLE_CPY for copy user access Tony Luck
2020-10-05 16:34 ` Borislav Petkov
2020-09-30 23:26 ` [PATCH v2 4/7] x86/mce: Avoid tail copy when machine check terminated a copy from user Tony Luck
2020-09-30 23:26 ` [PATCH v2 5/7] x86/mce: Change fault_in_kernel_space() from static to global Tony Luck
2020-10-05 16:33 ` Borislav Petkov
2020-09-30 23:26 ` [PATCH v2 6/7] x86/mce: Recover from poison found while copying from user space Tony Luck
2020-10-05 16:32 ` Borislav Petkov [this message]
2020-10-05 17:47 ` Luck, Tony
2020-09-30 23:26 ` [PATCH v2 7/7] x86/mce: Decode a kernel instruction to determine if it is copying from user Tony Luck
2020-10-05 16:31 ` Borislav Petkov
2020-10-06 21:09 ` [PATCH v3 0/6] Add machine check recovery when copying from user space Tony Luck
2020-10-06 21:09 ` [PATCH v3 1/6] x86/mce: Pass pointer to saved pt_regs to severity calculation routines Tony Luck
2020-10-07 10:02 ` [tip: ras/core] " tip-bot2 for Youquan Song
2020-10-06 21:09 ` [PATCH v3 2/6] x86/mce: Provide method to find out the type of exception handle Tony Luck
2020-10-07 10:02 ` [tip: ras/core] x86/mce: Provide method to find out the type of an exception handler tip-bot2 for Tony Luck
2020-10-06 21:09 ` [PATCH v3 3/6] x86/mce: Add _ASM_EXTABLE_CPY for copy user access Tony Luck
2020-10-07 10:02 ` [tip: ras/core] " tip-bot2 for Youquan Song
2020-10-06 21:09 ` [PATCH v3 4/6] x86/mce: Avoid tail copy when machine check terminated a copy from user Tony Luck
2020-10-07 8:23 ` David Laight
2020-10-07 18:49 ` Luck, Tony
2020-10-07 21:11 ` David Laight
2020-10-07 10:02 ` [tip: ras/core] " tip-bot2 for Tony Luck
2020-10-06 21:09 ` [PATCH v3 5/6] x86/mce: Recover from poison found while copying from user space Tony Luck
2020-10-07 10:02 ` [tip: ras/core] " tip-bot2 for Tony Luck
2020-10-06 21:09 ` [PATCH v3 6/6] x86/mce: Decode a kernel instruction to determine if it is copying from user Tony Luck
2020-10-07 10:02 ` [tip: ras/core] " tip-bot2 for Tony Luck
2020-09-09 15:05 ` [RESEND PATCH 0/8] Add machine check recovery when copying from user space Tony Luck
[not found] ` <20200908175519.14223-4-tony.luck@intel.com>
2020-09-15 9:11 ` [PATCH 3/8] x86/mce: Provide method to find out the type of exception handle Borislav Petkov
2020-09-15 16:24 ` Luck, Tony
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