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| author | Peter Zijlstra <peterz@infradead.org> | 2019-07-11 13:40:59 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-07-17 23:17:38 +0200 |
| commit | a0d14b8909de55139b8702fe0c7e80b69763dcfb (patch) | |
| tree | a9f6b04591b9087f4a64086c27ac46c09a2f82aa /arch/x86/entry/entry_32.S | |
| parent | x86/entry/64: Update comments and sanity tests for create_gap (diff) | |
| download | linux-a0d14b8909de55139b8702fe0c7e80b69763dcfb.tar.xz linux-a0d14b8909de55139b8702fe0c7e80b69763dcfb.zip | |
x86/mm, tracing: Fix CR2 corruption
Despite the current efforts to read CR2 before tracing happens there still
exist a number of possible holes:
idtentry page_fault do_page_fault has_error_code=1
call error_entry
TRACE_IRQS_OFF
call trace_hardirqs_off*
#PF // modifies CR2
CALL_enter_from_user_mode
__context_tracking_exit()
trace_user_exit(0)
#PF // modifies CR2
call do_page_fault
address = read_cr2(); /* whoopsie */
And similar for i386.
Fix it by pulling the CR2 read into the entry code, before any of that
stuff gets a chance to run and ruin things.
Reported-by: He Zhe <zhe.he@windriver.com>
Reported-by: Eiichi Tsukata <devel@etsukata.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: bp@alien8.de
Cc: rostedt@goodmis.org
Cc: torvalds@linux-foundation.org
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: jgross@suse.com
Cc: joel@joelfernandes.org
Link: https://lkml.kernel.org/r/20190711114336.116812491@infradead.org
Debugged-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'arch/x86/entry/entry_32.S')
| -rw-r--r-- | arch/x86/entry/entry_32.S | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 4d4b6100f0e8..2bb986f305ac 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -1443,9 +1443,28 @@ BUILD_INTERRUPT3(hv_stimer0_callback_vector, HYPERV_STIMER0_VECTOR, ENTRY(page_fault) ASM_CLAC - pushl $do_page_fault - ALIGN - jmp common_exception + pushl $0; /* %gs's slot on the stack */ + + SAVE_ALL switch_stacks=1 skip_gs=1 + + ENCODE_FRAME_POINTER + UNWIND_ESPFIX_STACK + + /* fixup %gs */ + GS_TO_REG %ecx + REG_TO_PTGS %ecx + SET_KERNEL_GS %ecx + + GET_CR2_INTO(%ecx) # might clobber %eax + + /* fixup orig %eax */ + movl PT_ORIG_EAX(%esp), %edx # get the error code + movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart + + TRACE_IRQS_OFF + movl %esp, %eax # pt_regs pointer + call do_page_fault + jmp ret_from_exception END(page_fault) common_exception: |