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authorWanpeng Li <wanpeng.li@hotmail.com>2016-09-30 09:01:06 +0800
committerIngo Molnar <mingo@kernel.org>2016-09-30 13:53:12 +0200
commit2fa5f04f85730d0c4f49f984b7efeb4f8d5bd1fc (patch)
tree18963452531142ae6e6b4a8609374dd23c54d4ac
parent05fb3c199bb09f5b85de56cc3ede194ac95c5e1f (diff)
x86/entry/64: Fix context tracking state warning when load_gs_index fails
This warning: WARNING: CPU: 0 PID: 3331 at arch/x86/entry/common.c:45 enter_from_user_mode+0x32/0x50 CPU: 0 PID: 3331 Comm: ldt_gdt_64 Not tainted 4.8.0-rc7+ #13 Call Trace: dump_stack+0x99/0xd0 __warn+0xd1/0xf0 warn_slowpath_null+0x1d/0x20 enter_from_user_mode+0x32/0x50 error_entry+0x6d/0xc0 ? general_protection+0x12/0x30 ? native_load_gs_index+0xd/0x20 ? do_set_thread_area+0x19c/0x1f0 SyS_set_thread_area+0x24/0x30 do_int80_syscall_32+0x7c/0x220 entry_INT80_compat+0x38/0x50 ... can be reproduced by running the GS testcase of the ldt_gdt test unit in the x86 selftests. do_int80_syscall_32() will call enter_form_user_mode() to convert context tracking state from user state to kernel state. The load_gs_index() call can fail with user gsbase, gsbase will be fixed up and proceed if this happen. However, enter_from_user_mode() will be called again in the fixed up path though it is context tracking kernel state currently. This patch fixes it by just fixing up gsbase and telling lockdep that IRQs are off once load_gs_index() failed with user gsbase. Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1475197266-3440-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/entry/entry_64.S4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index d172c619c449..02fff3ebfb87 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1002,7 +1002,6 @@ ENTRY(error_entry)
testb $3, CS+8(%rsp)
jz .Lerror_kernelspace
-.Lerror_entry_from_usermode_swapgs:
/*
* We entered from user mode or we're pretending to have entered
* from user mode due to an IRET fault.
@@ -1045,7 +1044,8 @@ ENTRY(error_entry)
* gsbase and proceed. We'll fix up the exception and land in
* .Lgs_change's error handler with kernel gsbase.
*/
- jmp .Lerror_entry_from_usermode_swapgs
+ SWAPGS
+ jmp .Lerror_entry_done
.Lbstep_iret:
/* Fix truncated RIP */

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