[PATCH v2 03/18] x86/dumpstack: Add get_stack_info() support for the SYSENTER stack
From: Andy Lutomirski
Date: Tue Nov 21 2017 - 23:48:10 EST
get_stack_info() doesn't currently know about the SYSENTER stack, so
unwinding will fail if we entered the kernel on the SYSENTER stack
and haven't fully switched off. Teach get_stack_info() about the
SYSENTER stack.
With future patches applied that run part of the entry code on the
SYSENTER stack and introduce an intentional BUG(), I would get:
[ 3.962218] PANIC: double fault, error_code: 0x0
...
[ 3.963998] task: ffff88001aa18000 task.stack: ffff88001aa20000
[ 3.964526] RIP: 0010:do_error_trap+0x33/0x1c0
[ 3.964947] RSP: 0000:ffffffffff1b8f78 EFLAGS: 00010096
[ 3.965439] RAX: dffffc0000000000 RBX: ffffffffff1b8f90 RCX: 0000000000000006
[ 3.966067] RDX: ffffffff82048b20 RSI: 0000000000000000 RDI: ffffffffff1b9110
[ 3.966696] RBP: ffffffffff1b9088 R08: 0000000000000004 R09: 0000000000000000
[ 3.967316] R10: 0000000000000000 R11: fffffbffffe3723f R12: 0000000000000006
[ 3.967939] R13: 0000000000000000 R14: 0000000000000004 R15: 0000000000000000
[ 3.968565] FS: 0000000000000000(0000) GS:ffff88001ae00000(0000) knlGS:0000000000000000
[ 3.969272] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 3.969776] CR2: ffffffffff1b8f68 CR3: 0000000019308002 CR4: 00000000003606f0
[ 3.970406] Call Trace:
[ 3.970632] Code: ...
With this patch, I get:
[ 4.211553] PANIC: double fault, error_code: 0x0
...
[ 4.213536] task: ffff88001aa18000 task.stack: ffff88001aa20000
[ 4.214059] RIP: 0010:do_error_trap+0x33/0x1c0
[ 4.214449] RSP: 0000:ffffffffff1b8f78 EFLAGS: 00010096
[ 4.214934] RAX: dffffc0000000000 RBX: ffffffffff1b8f90 RCX: 0000000000000006
[ 4.215554] RDX: ffffffff82048b20 RSI: 0000000000000000 RDI: ffffffffff1b9110
[ 4.216176] RBP: ffffffffff1b9088 R08: 0000000000000004 R09: 0000000000000000
[ 4.216793] R10: 0000000000000000 R11: fffffbffffe3723f R12: 0000000000000006
[ 4.217419] R13: 0000000000000000 R14: 0000000000000004 R15: 0000000000000000
[ 4.218046] FS: 0000000000000000(0000) GS:ffff88001ae00000(0000) knlGS:0000000000000000
[ 4.218775] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 4.219280] CR2: ffffffffff1b8f68 CR3: 00000000193da002 CR4: 00000000003606f0
[ 4.219931] Call Trace:
[ 4.220156] <SYSENTER>
[ 4.220383] ? async_page_fault+0x36/0x60
[ 4.220768] ? invalid_op+0x22/0x40
[ 4.221087] ? async_page_fault+0x36/0x60
[ 4.221442] ? sync_regs+0x3c/0x40
[ 4.221745] ? sync_regs+0x2e/0x40
[ 4.222051] ? error_entry+0x6c/0xd0
[ 4.222395] ? async_page_fault+0x36/0x60
[ 4.222748] </SYSENTER>
[ 4.223014] Code: ...
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
arch/x86/include/asm/stacktrace.h | 3 +++
arch/x86/kernel/dumpstack.c | 19 +++++++++++++++++++
arch/x86/kernel/dumpstack_32.c | 6 ++++++
arch/x86/kernel/dumpstack_64.c | 6 ++++++
4 files changed, 34 insertions(+)
diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 8da111b3c342..f8062bfd43a0 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -16,6 +16,7 @@ enum stack_type {
STACK_TYPE_TASK,
STACK_TYPE_IRQ,
STACK_TYPE_SOFTIRQ,
+ STACK_TYPE_SYSENTER,
STACK_TYPE_EXCEPTION,
STACK_TYPE_EXCEPTION_LAST = STACK_TYPE_EXCEPTION + N_EXCEPTION_STACKS-1,
};
@@ -28,6 +29,8 @@ struct stack_info {
bool in_task_stack(unsigned long *stack, struct task_struct *task,
struct stack_info *info);
+bool in_sysenter_stack(unsigned long *stack, struct stack_info *info);
+
int get_stack_info(unsigned long *stack, struct task_struct *task,
struct stack_info *info, unsigned long *visit_mask);
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index f13b4c00a5de..5e7d10e8ca25 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -43,6 +43,25 @@ bool in_task_stack(unsigned long *stack, struct task_struct *task,
return true;
}
+bool in_sysenter_stack(unsigned long *stack, struct stack_info *info)
+{
+ struct tss_struct *tss = this_cpu_ptr(&cpu_tss);
+
+ /* Treat the canary as part of the stack for unwinding purposes. */
+ void *begin = &tss->SYSENTER_stack_canary;
+ void *end = (void *)&tss->SYSENTER_stack + sizeof(tss->SYSENTER_stack);
+
+ if ((void *)stack < begin || (void *)stack >= end)
+ return false;
+
+ info->type = STACK_TYPE_SYSENTER;
+ info->begin = begin;
+ info->end = end;
+ info->next_sp = NULL;
+
+ return true;
+}
+
static void printk_stack_address(unsigned long address, int reliable,
char *log_lvl)
{
diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index daefae83a3aa..5ff13a6b3680 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -26,6 +26,9 @@ const char *stack_type_name(enum stack_type type)
if (type == STACK_TYPE_SOFTIRQ)
return "SOFTIRQ";
+ if (type == STACK_TYPE_SYSENTER)
+ return "SYSENTER";
+
return NULL;
}
@@ -93,6 +96,9 @@ int get_stack_info(unsigned long *stack, struct task_struct *task,
if (task != current)
goto unknown;
+ if (in_sysenter_stack(stack, info))
+ goto recursion_check;
+
if (in_hardirq_stack(stack, info))
goto recursion_check;
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 88ce2ffdb110..abc828f8c297 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -37,6 +37,9 @@ const char *stack_type_name(enum stack_type type)
if (type == STACK_TYPE_IRQ)
return "IRQ";
+ if (type == STACK_TYPE_SYSENTER)
+ return "SYSENTER";
+
if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
return exception_stack_names[type - STACK_TYPE_EXCEPTION];
@@ -115,6 +118,9 @@ int get_stack_info(unsigned long *stack, struct task_struct *task,
if (in_irq_stack(stack, info))
goto recursion_check;
+ if (in_sysenter_stack(stack, info))
+ goto recursion_check;
+
goto unknown;
recursion_check:
--
2.13.6