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Subject[tip:perf/probes] kprobes/x86-32: Move irq-exit functions to kprobes section
Commit-ID:  a00e817f42663941ea0aa5f85a9d1c4f8b212839
Gitweb: http://git.kernel.org/tip/a00e817f42663941ea0aa5f85a9d1c4f8b212839
Author: Masami Hiramatsu <mhiramat@redhat.com>
AuthorDate: Tue, 8 Sep 2009 12:47:55 -0400
Committer: Frederic Weisbecker <fweisbec@gmail.com>
CommitDate: Fri, 11 Sep 2009 03:59:35 +0200

kprobes/x86-32: Move irq-exit functions to kprobes section

Move irq-exit functions to .kprobes.text section to protect against
kprobes recursion.

When I ran kprobe stress test on x86-32, I found below symbols
cause unrecoverable recursive probing:

ret_from_exception
ret_from_intr
check_userspace
restore_all
restore_all_notrace
restore_nocheck
irq_return

And also, I found some interrupt/exception entry points that
cause similar problems.

This patch moves those symbols (including their container functions)
to .kprobes.text section to prevent any kprobes probing.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <20090908164755.24050.81182.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
arch/x86/kernel/entry_32.S | 24 ++++++++++++++++++++++++
kernel/kprobes.c | 2 ++
2 files changed, 26 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index c097e7d..beb30da 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -334,6 +334,10 @@ ENTRY(ret_from_fork)
END(ret_from_fork)

/*
+ * Interrupt exit functions should be protected against kprobes
+ */
+ .pushsection .kprobes.text, "ax"
+/*
* Return to user mode is not as complex as all this looks,
* but we want the default path for a system call return to
* go as quickly as possible which is why some of this is
@@ -383,6 +387,10 @@ need_resched:
END(resume_kernel)
#endif
CFI_ENDPROC
+/*
+ * End of kprobes section
+ */
+ .popsection

/* SYSENTER_RETURN points to after the "sysenter" instruction in
the vsyscall page. See vsyscall-sysentry.S, which defines the symbol. */
@@ -513,6 +521,10 @@ sysexit_audit:
PTGS_TO_GS_EX
ENDPROC(ia32_sysenter_target)

+/*
+ * syscall stub including irq exit should be protected against kprobes
+ */
+ .pushsection .kprobes.text, "ax"
# system call handler stub
ENTRY(system_call)
RING0_INT_FRAME # can't unwind into user space anyway
@@ -705,6 +717,10 @@ syscall_badsys:
jmp resume_userspace
END(syscall_badsys)
CFI_ENDPROC
+/*
+ * End of kprobes section
+ */
+ .popsection

/*
* System calls that need a pt_regs pointer.
@@ -814,6 +830,10 @@ common_interrupt:
ENDPROC(common_interrupt)
CFI_ENDPROC

+/*
+ * Irq entries should be protected against kprobes
+ */
+ .pushsection .kprobes.text, "ax"
#define BUILD_INTERRUPT3(name, nr, fn) \
ENTRY(name) \
RING0_INT_FRAME; \
@@ -980,6 +1000,10 @@ ENTRY(spurious_interrupt_bug)
jmp error_code
CFI_ENDPROC
END(spurious_interrupt_bug)
+/*
+ * End of kprobes section
+ */
+ .popsection

ENTRY(kernel_thread_helper)
pushl $0 # fake return address for unwinder
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 3267d90..00d01b0 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -91,6 +91,8 @@ static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
static struct kprobe_blackpoint kprobe_blacklist[] = {
{"preempt_schedule",},
{"native_get_debugreg",},
+ {"irq_entries_start",},
+ {"common_interrupt",},
{NULL} /* Terminator */
};


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