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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 <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134340.611961721@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-02-25 23:08:05 +01:00
parent 8f159f1dfa
commit dd8e2d9ae6
4 changed files with 19 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
arch/x86/entry/common.c
View File

@ -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)

12
arch/x86/entry/entry_32.S
View File

@ -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:

2
arch/x86/entry/entry_64.S
View File

@ -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

18
arch/x86/entry/entry_64_compat.S
View File

@ -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: