The following commit has been merged into the x86/entry branch of tip:
Commit-ID: f0fd87b82db7b0102ba98991fa36c2318d2e2894
Gitweb:
https://git.kernel.org/tip/f0fd87b82db7b0102ba98991fa36c2318d2e2894
Author: Thomas Gleixner <t...@linutronix.de>
AuthorDate: Tue, 25 Feb 2020 23:08:05 +01:00
Committer: Thomas Gleixner <t...@linutronix.de>
CommitterDate: Tue, 19 May 2020 16:03:51 +02:00
x86/entry: Move irq tracing on syscall entry to C-code
Now that the C entry points are safe, move the irq flags tracing code into
the entry helper:
- Invoke lockdep before calling into context tracking
- Use the safe trace_hardirqs_on_prepare() trace function after context
tracking established state and RCU is watching.
enter_from_user_mode() is also still invoked from the exception/interrupt
entry code which still contains the ASM irq flags tracing. So this is just
a redundant and harmless invocation of tracing / lockdep until these are
removed as well.
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.char...@oracle.com>
Acked-by: Peter Zijlstra <pet...@infradead.org>
Link: https://lkml.kernel.org/r/20200505134340.611961...@linutronix.de
---
arch/x86/entry/common.c | 21 +++++++++++++++++++--
arch/x86/entry/entry_32.S | 12 ------------
arch/x86/entry/entry_64.S | 2 --
arch/x86/entry/entry_64_compat.S | 18 ------------------
4 files changed, 19 insertions(+), 34 deletions(-)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 9892fb7..7473c12 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -40,19 +40,36 @@
#include <trace/events/syscalls.h>
#ifdef CONFIG_CONTEXT_TRACKING
-/* Called on entry from user mode with IRQs off. */
+/**
+ * enter_from_user_mode - Establish state when coming from user mode
+ *
+ * Syscall entry disables interrupts, but user mode is traced as interrupts
+ * enabled. Also with NO_HZ_FULL RCU might be idle.
+ *
+ * 1) Tell lockdep that interrupts are disabled
+ * 2) Invoke context tracking if enabled to reactivate RCU
+ * 3) Trace interrupts off state
+ */
__visible noinstr void enter_from_user_mode(void)
{
enum ctx_state state = ct_state();
+ lockdep_hardirqs_off(CALLER_ADDR0);
user_exit_irqoff();
instrumentation_begin();
CT_WARN_ON(state != CONTEXT_USER);
+ trace_hardirqs_off_prepare();
instrumentation_end();
}
#else
-static inline void enter_from_user_mode(void) {}
+static __always_inline void enter_from_user_mode(void)
+{
+ lockdep_hardirqs_off(CALLER_ADDR0);
+ instrumentation_begin();
+ trace_hardirqs_off_prepare();
+ instrumentation_end();
+}
#endif
static noinstr void exit_to_user_mode(void)
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index bf0082b..65704e0 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -967,12 +967,6 @@ SYM_FUNC_START(entry_SYSENTER_32)
jnz .Lsysenter_fix_flags
.Lsysenter_flags_fixed:
- /*
- * User mode is traced as though IRQs are on, and SYSENTER
- * turned them off.
- */
- TRACE_IRQS_OFF
-
movl %esp, %eax
call do_fast_syscall_32
/* XEN PV guests always use IRET path */
@@ -1082,12 +1076,6 @@ SYM_FUNC_START(entry_INT80_32)
SAVE_ALL pt_regs_ax=$-ENOSYS switch_stacks=1 /* save rest */
- /*
- * User mode is traced as though IRQs are on, and the interrupt gate
- * turned them off.
- */
- TRACE_IRQS_OFF
-
movl %esp, %eax
call do_int80_syscall_32
.Lsyscall_32_done:
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index b199f43..9e34fe8 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -167,8 +167,6 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_hwframe,
SYM_L_GLOBAL)
PUSH_AND_CLEAR_REGS rax=$-ENOSYS
- TRACE_IRQS_OFF
-
/* IRQs are off. */
movq %rax, %rdi
movq %rsp, %rsi
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index f1d3cca..e2e8bd7 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -129,12 +129,6 @@ SYM_FUNC_START(entry_SYSENTER_compat)
jnz .Lsysenter_fix_flags
.Lsysenter_flags_fixed:
- /*
- * User mode is traced as though IRQs are on, and SYSENTER
- * turned them off.
- */
- TRACE_IRQS_OFF
-
movq %rsp, %rdi
call do_fast_syscall_32
/* XEN PV guests always use IRET path */
@@ -247,12 +241,6 @@ SYM_INNER_LABEL(entry_SYSCALL_compat_after_hwframe,
SYM_L_GLOBAL)
pushq $0 /* pt_regs->r15 = 0 */
xorl %r15d, %r15d /* nospec r15 */
- /*
- * User mode is traced as though IRQs are on, and SYSENTER
- * turned them off.
- */
- TRACE_IRQS_OFF
-
movq %rsp, %rdi
call do_fast_syscall_32
/* XEN PV guests always use IRET path */
@@ -403,12 +391,6 @@ SYM_CODE_START(entry_INT80_compat)
xorl %r15d, %r15d /* nospec r15 */
cld
- /*
- * User mode is traced as though IRQs are on, and the interrupt
- * gate turned them off.
- */
- TRACE_IRQS_OFF
-
movq %rsp, %rdi
call do_int80_syscall_32
.Lsyscall_32_done:
