x86: Exception hooks for userspace RCU extended QS
Add necessary hooks to x86 exception for userspace
RCU extended quiescent state support.
This includes traps, page fault, debug exceptions, etc...
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Alessio Igor Bogani <abogani@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Avi Kivity <avi@redhat.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Max Krasnyansky <maxk@qualcomm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/arch/x86/include/asm/rcu.h b/arch/x86/include/asm/rcu.h
new file mode 100644
index 0000000..439815b
--- /dev/null
+++ b/arch/x86/include/asm/rcu.h
@@ -0,0 +1,20 @@
+#ifndef _ASM_X86_RCU_H
+#define _ASM_X86_RCU_H
+
+#include <linux/rcupdate.h>
+#include <asm/ptrace.h>
+
+static inline void exception_enter(struct pt_regs *regs)
+{
+ rcu_user_exit();
+}
+
+static inline void exception_exit(struct pt_regs *regs)
+{
+#ifdef CONFIG_RCU_USER_QS
+ if (user_mode(regs))
+ rcu_user_enter();
+#endif
+}
+
+#endif
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 74850e5..3789675 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -55,6 +55,7 @@
#include <asm/i387.h>
#include <asm/fpu-internal.h>
#include <asm/mce.h>
+#include <asm/rcu.h>
#include <asm/mach_traps.h>
@@ -180,11 +181,15 @@
#define DO_ERROR(trapnr, signr, str, name) \
dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
{ \
- if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
- == NOTIFY_STOP) \
+ exception_enter(regs); \
+ if (notify_die(DIE_TRAP, str, regs, error_code, \
+ trapnr, signr) == NOTIFY_STOP) { \
+ exception_exit(regs); \
return; \
+ } \
conditional_sti(regs); \
do_trap(trapnr, signr, str, regs, error_code, NULL); \
+ exception_exit(regs); \
}
#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
@@ -195,11 +200,15 @@
info.si_errno = 0; \
info.si_code = sicode; \
info.si_addr = (void __user *)siaddr; \
- if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
- == NOTIFY_STOP) \
+ exception_enter(regs); \
+ if (notify_die(DIE_TRAP, str, regs, error_code, \
+ trapnr, signr) == NOTIFY_STOP) { \
+ exception_exit(regs); \
return; \
+ } \
conditional_sti(regs); \
do_trap(trapnr, signr, str, regs, error_code, &info); \
+ exception_exit(regs); \
}
DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV,
@@ -222,12 +231,14 @@
/* Runs on IST stack */
dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
{
+ exception_enter(regs);
if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
- X86_TRAP_SS, SIGBUS) == NOTIFY_STOP)
- return;
- preempt_conditional_sti(regs);
- do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
- preempt_conditional_cli(regs);
+ X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
+ preempt_conditional_sti(regs);
+ do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
+ preempt_conditional_cli(regs);
+ }
+ exception_exit(regs);
}
dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
@@ -235,6 +246,7 @@
static const char str[] = "double fault";
struct task_struct *tsk = current;
+ exception_enter(regs);
/* Return not checked because double check cannot be ignored */
notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
@@ -255,27 +267,28 @@
{
struct task_struct *tsk;
+ exception_enter(regs);
conditional_sti(regs);
#ifdef CONFIG_X86_32
if (regs->flags & X86_VM_MASK) {
local_irq_enable();
handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
- return;
+ goto exit;
}
#endif
tsk = current;
if (!user_mode(regs)) {
if (fixup_exception(regs))
- return;
+ goto exit;
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = X86_TRAP_GP;
- if (!notify_die(DIE_GPF, "general protection fault", regs, error_code,
- X86_TRAP_GP, SIGSEGV) == NOTIFY_STOP)
+ if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
+ X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
die("general protection fault", regs, error_code);
- return;
+ goto exit;
}
tsk->thread.error_code = error_code;
@@ -291,7 +304,8 @@
}
force_sig(SIGSEGV, tsk);
- return;
+exit:
+ exception_exit(regs);
}
/* May run on IST stack. */
@@ -306,15 +320,16 @@
ftrace_int3_handler(regs))
return;
#endif
+ exception_enter(regs);
#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
SIGTRAP) == NOTIFY_STOP)
- return;
+ goto exit;
#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
SIGTRAP) == NOTIFY_STOP)
- return;
+ goto exit;
/*
* Let others (NMI) know that the debug stack is in use
@@ -325,6 +340,8 @@
do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
preempt_conditional_cli(regs);
debug_stack_usage_dec();
+exit:
+ exception_exit(regs);
}
#ifdef CONFIG_X86_64
@@ -385,6 +402,8 @@
unsigned long dr6;
int si_code;
+ exception_enter(regs);
+
get_debugreg(dr6, 6);
/* Filter out all the reserved bits which are preset to 1 */
@@ -400,7 +419,7 @@
/* Catch kmemcheck conditions first of all! */
if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
- return;
+ goto exit;
/* DR6 may or may not be cleared by the CPU */
set_debugreg(0, 6);
@@ -415,7 +434,7 @@
if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
SIGTRAP) == NOTIFY_STOP)
- return;
+ goto exit;
/*
* Let others (NMI) know that the debug stack is in use
@@ -431,7 +450,7 @@
X86_TRAP_DB);
preempt_conditional_cli(regs);
debug_stack_usage_dec();
- return;
+ goto exit;
}
/*
@@ -452,7 +471,8 @@
preempt_conditional_cli(regs);
debug_stack_usage_dec();
- return;
+exit:
+ exception_exit(regs);
}
/*
@@ -549,14 +569,17 @@
#ifdef CONFIG_X86_32
ignore_fpu_irq = 1;
#endif
-
+ exception_enter(regs);
math_error(regs, error_code, X86_TRAP_MF);
+ exception_exit(regs);
}
dotraplinkage void
do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
{
+ exception_enter(regs);
math_error(regs, error_code, X86_TRAP_XF);
+ exception_exit(regs);
}
dotraplinkage void
@@ -623,6 +646,7 @@
dotraplinkage void __kprobes
do_device_not_available(struct pt_regs *regs, long error_code)
{
+ exception_enter(regs);
#ifdef CONFIG_MATH_EMULATION
if (read_cr0() & X86_CR0_EM) {
struct math_emu_info info = { };
@@ -631,6 +655,7 @@
info.regs = regs;
math_emulate(&info);
+ exception_exit(regs);
return;
}
#endif
@@ -638,12 +663,15 @@
#ifdef CONFIG_X86_32
conditional_sti(regs);
#endif
+ exception_exit(regs);
}
#ifdef CONFIG_X86_32
dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
{
siginfo_t info;
+
+ exception_enter(regs);
local_irq_enable();
info.si_signo = SIGILL;
@@ -651,10 +679,11 @@
info.si_code = ILL_BADSTK;
info.si_addr = NULL;
if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
- X86_TRAP_IRET, SIGILL) == NOTIFY_STOP)
- return;
- do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
- &info);
+ X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
+ do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
+ &info);
+ }
+ exception_exit(regs);
}
#endif
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 76dcd9d..7dde46d 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -18,6 +18,7 @@
#include <asm/pgalloc.h> /* pgd_*(), ... */
#include <asm/kmemcheck.h> /* kmemcheck_*(), ... */
#include <asm/fixmap.h> /* VSYSCALL_START */
+#include <asm/rcu.h> /* exception_enter(), ... */
/*
* Page fault error code bits:
@@ -1000,8 +1001,8 @@
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
-dotraplinkage void __kprobes
-do_page_fault(struct pt_regs *regs, unsigned long error_code)
+static void __kprobes
+__do_page_fault(struct pt_regs *regs, unsigned long error_code)
{
struct vm_area_struct *vma;
struct task_struct *tsk;
@@ -1209,3 +1210,11 @@
up_read(&mm->mmap_sem);
}
+
+dotraplinkage void __kprobes
+do_page_fault(struct pt_regs *regs, unsigned long error_code)
+{
+ exception_enter(regs);
+ __do_page_fault(regs, error_code);
+ exception_exit(regs);
+}