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Merge tag 'core-rcu-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Browse Source 
Pull RCU updates from Ingo Molnar:
 "The RCU updates for this cycle were:

   - RCU-tasks update, including addition of RCU Tasks Trace for BPF use
     and TASKS_RUDE_RCU

   - kfree_rcu() updates.

   - Remove scheduler locking restriction

   - RCU CPU stall warning updates.

   - Torture-test updates.

   - Miscellaneous fixes and other updates"

* tag 'core-rcu-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (103 commits)
  rcu: Allow for smp_call_function() running callbacks from idle
  rcu: Provide rcu_irq_exit_check_preempt()
  rcu: Abstract out rcu_irq_enter_check_tick() from rcu_nmi_enter()
  rcu: Provide __rcu_is_watching()
  rcu: Provide rcu_irq_exit_preempt()
  rcu: Make RCU IRQ enter/exit functions rely on in_nmi()
  rcu/tree: Mark the idle relevant functions noinstr
  x86: Replace ist_enter() with nmi_enter()
  x86/mce: Send #MC singal from task work
  x86/entry: Get rid of ist_begin/end_non_atomic()
  sched,rcu,tracing: Avoid tracing before in_nmi() is correct
  sh/ftrace: Move arch_ftrace_nmi_{enter,exit} into nmi exception
  lockdep: Always inline lockdep_{off,on}()
  hardirq/nmi: Allow nested nmi_enter()
  arm64: Prepare arch_nmi_enter() for recursion
  printk: Disallow instrumenting print_nmi_enter()
  printk: Prepare for nested printk_nmi_enter()
  rcutorture: Convert ULONG_CMP_LT() to time_before()
  torture: Add a --kasan argument
  torture: Save a few lines by using config_override_param initially
  ...
This commit is contained in:
Linus Torvalds
2020-06-01 12:56:29 -07:00
parent 0bd957eb11 cb3cb6733f
commit 2227e5b21a
62 changed files with 2536 additions and 947 deletions
Download Patch File Download Diff File Expand all files Collapse all files

63
arch/x86/kernel/cpu/mce/core.c
View File

@@ -42,6 +42,8 @@
#include <linux/export.h>
#include <linux/jump_label.h>
#include <linux/set_memory.h>
#include <linux/task_work.h>
#include <linux/hardirq.h>
#include <asm/intel-family.h>
#include <asm/processor.h>
@@ -1086,23 +1088,6 @@ static void mce_clear_state(unsigned long *toclear)
}
}
static int do_memory_failure(struct mce *m)
{
int flags = MF_ACTION_REQUIRED;
int ret;
pr_err("Uncorrected hardware memory error in user-access at %llx", m->addr);
if (!(m->mcgstatus & MCG_STATUS_RIPV))
flags |= MF_MUST_KILL;
ret = memory_failure(m->addr >> PAGE_SHIFT, flags);
if (ret)
pr_err("Memory error not recovered");
else
set_mce_nospec(m->addr >> PAGE_SHIFT);
return ret;
}
/*
* Cases where we avoid rendezvous handler timeout:
* 1) If this CPU is offline.
@@ -1204,6 +1189,29 @@ static void __mc_scan_banks(struct mce *m, struct mce *final,
*m = *final;
}
static void kill_me_now(struct callback_head *ch)
{
force_sig(SIGBUS);
}
static void kill_me_maybe(struct callback_head *cb)
{
struct task_struct *p = container_of(cb, struct task_struct, mce_kill_me);
int flags = MF_ACTION_REQUIRED;
pr_err("Uncorrected hardware memory error in user-access at %llx", p->mce_addr);
if (!(p->mce_status & MCG_STATUS_RIPV))
flags |= MF_MUST_KILL;
if (!memory_failure(p->mce_addr >> PAGE_SHIFT, flags)) {
set_mce_nospec(p->mce_addr >> PAGE_SHIFT);
return;
}
pr_err("Memory error not recovered");
kill_me_now(cb);
}
/*
* The actual machine check handler. This only handles real
* exceptions when something got corrupted coming in through int 18.
@@ -1222,7 +1230,7 @@ static void __mc_scan_banks(struct mce *m, struct mce *final,
* backing the user stack, tracing that reads the user stack will cause
* potentially infinite recursion.
*/
void notrace do_machine_check(struct pt_regs *regs, long error_code)
void noinstr do_machine_check(struct pt_regs *regs, long error_code)
{
DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);
DECLARE_BITMAP(toclear, MAX_NR_BANKS);
@@ -1259,7 +1267,7 @@ void notrace do_machine_check(struct pt_regs *regs, long error_code)
if (__mc_check_crashing_cpu(cpu))
return;
ist_enter(regs);
nmi_enter();
this_cpu_inc(mce_exception_count);
@@ -1352,23 +1360,24 @@ void notrace do_machine_check(struct pt_regs *regs, long error_code)
/* Fault was in user mode and we need to take some action */
if ((m.cs & 3) == 3) {
ist_begin_non_atomic(regs);
local_irq_enable();
/* If this triggers there is no way to recover. Die hard. */
BUG_ON(!on_thread_stack() || !user_mode(regs));
if (kill_it || do_memory_failure(&m))
force_sig(SIGBUS);
local_irq_disable();
ist_end_non_atomic();
current->mce_addr = m.addr;
current->mce_status = m.mcgstatus;
current->mce_kill_me.func = kill_me_maybe;
if (kill_it)
current->mce_kill_me.func = kill_me_now;
task_work_add(current, &current->mce_kill_me, true);
} else {
if (!fixup_exception(regs, X86_TRAP_MC, error_code, 0))
mce_panic("Failed kernel mode recovery", &m, msg);
}
out_ist:
ist_exit(regs);
nmi_exit();
}
EXPORT_SYMBOL_GPL(do_machine_check);
NOKPROBE_SYMBOL(do_machine_check);
#ifndef CONFIG_MEMORY_FAILURE
int memory_failure(unsigned long pfn, int flags)

5
arch/x86/kernel/cpu/mce/p5.c
View File

@@ -7,6 +7,7 @@
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/smp.h>
#include <linux/hardirq.h>
#include <asm/processor.h>
#include <asm/traps.h>
@@ -24,7 +25,7 @@ static void pentium_machine_check(struct pt_regs *regs, long error_code)
{
u32 loaddr, hi, lotype;
ist_enter(regs);
nmi_enter();
rdmsr(MSR_IA32_P5_MC_ADDR, loaddr, hi);
rdmsr(MSR_IA32_P5_MC_TYPE, lotype, hi);
@@ -39,7 +40,7 @@ static void pentium_machine_check(struct pt_regs *regs, long error_code)
add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);
ist_exit(regs);
nmi_exit();
}
/* Set up machine check reporting for processors with Intel style MCE: */

5
arch/x86/kernel/cpu/mce/winchip.c
View File

@@ -6,6 +6,7 @@
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/hardirq.h>
#include <asm/processor.h>
#include <asm/traps.h>
@@ -18,12 +19,12 @@
/* Machine check handler for WinChip C6: */
static void winchip_machine_check(struct pt_regs *regs, long error_code)
{
ist_enter(regs);
nmi_enter();
pr_emerg("CPU0: Machine Check Exception.\n");
add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);
ist_exit(regs);
nmi_exit();
}
/* Set up machine check reporting on the Winchip C6 series */

108
arch/x86/kernel/traps.c
View File

@@ -37,10 +37,12 @@
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/io.h>
#include <linux/hardirq.h>
#include <linux/atomic.h>
#include <asm/stacktrace.h>
#include <asm/processor.h>
#include <asm/debugreg.h>
#include <linux/atomic.h>
#include <asm/text-patching.h>
#include <asm/ftrace.h>
#include <asm/traps.h>
@@ -82,78 +84,6 @@ static inline void cond_local_irq_disable(struct pt_regs *regs)
local_irq_disable();
}
/*
* In IST context, we explicitly disable preemption. This serves two
* purposes: it makes it much less likely that we would accidentally
* schedule in IST context and it will force a warning if we somehow
* manage to schedule by accident.
*/
void ist_enter(struct pt_regs *regs)
{
if (user_mode(regs)) {
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
} else {
/*
* We might have interrupted pretty much anything. In
* fact, if we're a machine check, we can even interrupt
* NMI processing. We don't want in_nmi() to return true,
* but we need to notify RCU.
*/
rcu_nmi_enter();
}
preempt_disable();
/* This code is a bit fragile. Test it. */
RCU_LOCKDEP_WARN(!rcu_is_watching(), "ist_enter didn't work");
}
NOKPROBE_SYMBOL(ist_enter);
void ist_exit(struct pt_regs *regs)
{
preempt_enable_no_resched();
if (!user_mode(regs))
rcu_nmi_exit();
}
/**
* ist_begin_non_atomic() - begin a non-atomic section in an IST exception
* @regs: regs passed to the IST exception handler
*
* IST exception handlers normally cannot schedule. As a special
* exception, if the exception interrupted userspace code (i.e.
* user_mode(regs) would return true) and the exception was not
* a double fault, it can be safe to schedule. ist_begin_non_atomic()
* begins a non-atomic section within an ist_enter()/ist_exit() region.
* Callers are responsible for enabling interrupts themselves inside
* the non-atomic section, and callers must call ist_end_non_atomic()
* before ist_exit().
*/
void ist_begin_non_atomic(struct pt_regs *regs)
{
BUG_ON(!user_mode(regs));
/*
* Sanity check: we need to be on the normal thread stack. This
* will catch asm bugs and any attempt to use ist_preempt_enable
* from double_fault.
*/
BUG_ON(!on_thread_stack());
preempt_enable_no_resched();
}
/**
* ist_end_non_atomic() - begin a non-atomic section in an IST exception
*
* Ends a non-atomic section started with ist_begin_non_atomic().
*/
void ist_end_non_atomic(void)
{
preempt_disable();
}
int is_valid_bugaddr(unsigned long addr)
{
unsigned short ud;
@@ -363,7 +293,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
* The net result is that our #GP handler will think that we
* entered from usermode with the bad user context.
*
* No need for ist_enter here because we don't use RCU.
* No need for nmi_enter() here because we don't use RCU.
*/
if (((long)regs->sp >> P4D_SHIFT) == ESPFIX_PGD_ENTRY &&
regs->cs == __KERNEL_CS &&
@@ -398,7 +328,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
}
#endif
ist_enter(regs);
nmi_enter();
notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
tsk->thread.error_code = error_code;
@@ -592,19 +522,13 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
return;
/*
* Unlike any other non-IST entry, we can be called from a kprobe in
* non-CONTEXT_KERNEL kernel mode or even during context tracking
* state changes. Make sure that we wake up RCU even if we're coming
* from kernel code.
*
* This means that we can't schedule even if we came from a
* preemptible kernel context. That's okay.
* Unlike any other non-IST entry, we can be called from pretty much
* any location in the kernel through kprobes -- text_poke() will most
* likely be handled by poke_int3_handler() above. This means this
* handler is effectively NMI-like.
*/
if (!user_mode(regs)) {
rcu_nmi_enter();
preempt_disable();
}
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
if (!user_mode(regs))
nmi_enter();
#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
@@ -626,10 +550,8 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
cond_local_irq_disable(regs);
exit:
if (!user_mode(regs)) {
preempt_enable_no_resched();
rcu_nmi_exit();
}
if (!user_mode(regs))
nmi_exit();
}
NOKPROBE_SYMBOL(do_int3);
@@ -733,7 +655,7 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
unsigned long dr6;
int si_code;
ist_enter(regs);
nmi_enter();
get_debugreg(dr6, 6);
/*
@@ -826,7 +748,7 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
debug_stack_usage_dec();
exit:
ist_exit(regs);
nmi_exit();
}
NOKPROBE_SYMBOL(do_debug);