Merge tag 'x86-entry-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 entry code updates from Thomas Gleixner:

 - Convert the 32bit syscalls to be pt_regs based which removes the
   requirement to push all 6 potential arguments onto the stack and
   consolidates the interface with the 64bit variant

 - The first small portion of the exception and syscall related entry
   code consolidation which aims to address the recently discovered
   issues vs. RCU, int3, NMI and some other exceptions which can
   interrupt any context. The bulk of the changes is still work in
   progress and aimed for 5.8.

 - A few lockdep namespace cleanups which have been applied into this
   branch to keep the prerequisites for the ongoing work confined.

* tag 'x86-entry-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (35 commits)
  x86/entry: Fix build error x86 with !CONFIG_POSIX_TIMERS
  lockdep: Rename trace_{hard,soft}{irq_context,irqs_enabled}()
  lockdep: Rename trace_softirqs_{on,off}()
  lockdep: Rename trace_hardirq_{enter,exit}()
  x86/entry: Rename ___preempt_schedule
  x86: Remove unneeded includes
  x86/entry: Drop asmlinkage from syscalls
  x86/entry/32: Enable pt_regs based syscalls
  x86/entry/32: Use IA32-specific wrappers for syscalls taking 64-bit arguments
  x86/entry/32: Rename 32-bit specific syscalls
  x86/entry/32: Clean up syscall_32.tbl
  x86/entry: Remove ABI prefixes from functions in syscall tables
  x86/entry/64: Add __SYSCALL_COMMON()
  x86/entry: Remove syscall qualifier support
  x86/entry/64: Remove ptregs qualifier from syscall table
  x86/entry: Move max syscall number calculation to syscallhdr.sh
  x86/entry/64: Split X32 syscall table into its own file
  x86/entry/64: Move sys_ni_syscall stub to common.c
  x86/entry/64: Use syscall wrappers for x32_rt_sigreturn
  x86/entry: Refactor SYS_NI macros
  ...

2 files changed, 13 insertions, 2 deletions

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index dd06fce537fc..54165f3569e8 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1215,8 +1215,14 @@ static void __mc_scan_banks(struct mce *m, struct mce *final,
  * On Intel systems this is entered on all CPUs in parallel through
  * MCE broadcast. However some CPUs might be broken beyond repair,
  * so be always careful when synchronizing with others.
+ *
+ * Tracing and kprobes are disabled: if we interrupted a kernel context
+ * with IF=1, we need to minimize stack usage.  There are also recursion
+ * issues: if the machine check was due to a failure of the memory
+ * backing the user stack, tracing that reads the user stack will cause
+ * potentially infinite recursion.
  */
-void do_machine_check(struct pt_regs *regs, long error_code)
+void notrace do_machine_check(struct pt_regs *regs, long error_code)
 {
 	DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);
 	DECLARE_BITMAP(toclear, MAX_NR_BANKS);
@@ -1362,6 +1368,7 @@ out_ist:
 	ist_exit(regs);
 }
 EXPORT_SYMBOL_GPL(do_machine_check);
+NOKPROBE_SYMBOL(do_machine_check);
 
 #ifndef CONFIG_MEMORY_FAILURE
 int memory_failure(unsigned long pfn, int flags)
@@ -1896,10 +1903,11 @@ 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)
+dotraplinkage notrace void do_mce(struct pt_regs *regs, long error_code)
 {
 	machine_check_vector(regs, error_code);
 }
+NOKPROBE_SYMBOL(do_mce);
 
 /*
  * Called for each booted CPU to set up machine checks.
diff --git a/arch/x86/kernel/cpu/mce/internal.h b/arch/x86/kernel/cpu/mce/internal.h
index 97db18441d2c..3b008172ad73 100644
--- a/arch/x86/kernel/cpu/mce/internal.h
+++ b/arch/x86/kernel/cpu/mce/internal.h
@@ -8,6 +8,9 @@
 #include <linux/device.h>
 #include <asm/mce.h>
 
+/* Pointer to the installed machine check handler for this CPU setup. */
+extern void (*machine_check_vector)(struct pt_regs *, long error_code);
+
 enum severity_level {
 	MCE_NO_SEVERITY,
 	MCE_DEFERRED_SEVERITY,