x86/mce: Make machine check speculation protected

commit 6f41c34 upstream. The machine check idtentry uses an indirect branch directly from the low level code. This evades the speculation protection. Replace it by a direct call into C code and issue the indirect call there so the compiler can apply the proper speculation protection. Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by:Borislav Petkov <[email protected]> Reviewed-by: David Woodhouse <[email protected]> Niced-by: Peter Zijlstra <[email protected]> Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801181626290.1847@nanos Signed-off-by: Greg Kroah-Hartman <[email protected]>
jdobaj · Jan 23, 2018 · c5aa687 · c5aa687
1 parent 87ac297
commit c5aa687
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Showing 3 changed files with 7 additions and 1 deletion.
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
@@ -1064,7 +1064,7 @@ idtentry async_page_fault	do_async_page_fault	has_error_code=1
 #endif
 
 #ifdef CONFIG_X86_MCE
-idtentry machine_check					has_error_code=0	paranoid=1 do_sym=*machine_check_vector(%rip)
+idtentry machine_check		do_mce			has_error_code=0	paranoid=1
 #endif
 
 /*

diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
@@ -92,6 +92,7 @@ dotraplinkage void do_simd_coprocessor_error(struct pt_regs *, long);
 #ifdef CONFIG_X86_32
 dotraplinkage void do_iret_error(struct pt_regs *, long);
 #endif
+dotraplinkage void do_mce(struct pt_regs *, long);
 
 static inline int get_si_code(unsigned long condition)
 {

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1754,6 +1754,11 @@ static void unexpected_machine_check(struct pt_regs *regs, long error_code)
 void (*machine_check_vector)(struct pt_regs *, long error_code) =
 						unexpected_machine_check;
 
+dotraplinkage void do_mce(struct pt_regs *regs, long error_code)
+{
+	machine_check_vector(regs, error_code);
+}
+
 /*
  * Called for each booted CPU to set up machine checks.
  * Must be called with preempt off:
-Original file line number
+Diff line change
@@ Expand Up @@
     #endif
     #ifdef CONFIG_X86_MCE
-    idtentry machine_check					has_error_code=0	paranoid=1 do_sym=*machine_check_vector(%rip)
+    idtentry machine_check		do_mce			has_error_code=0	paranoid=1
     #endif
     /*
@@ Expand Down @@