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authorThomas Gleixner <tglx@linutronix.de>2019-11-11 23:03:23 +0100
committerThomas Gleixner <tglx@linutronix.de>2019-11-16 11:24:03 +0100
commit22fe5b0439dd53643fd6f4c582c46c6dba0fde53 (patch)
treee74ed4d8d8f6182811570d21185a7703e76e56d7 /arch/x86/entry
parent060aa16fdb7c5078a4159a76e5dc87d6a493af9b (diff)
downloadlinux-22fe5b0439dd53643fd6f4c582c46c6dba0fde53.tar.bz2
x86/ioperm: Move TSS bitmap update to exit to user work
There is no point to update the TSS bitmap for tasks which use I/O bitmaps on every context switch. It's enough to update it right before exiting to user space. That reduces the context switch bitmap handling to invalidating the io bitmap base offset in the TSS when the outgoing task has TIF_IO_BITMAP set. The invaldiation is done on purpose when a task with an IO bitmap switches out to prevent any possible leakage of an activated IO bitmap. It also removes the requirement to update the tasks bitmap atomically in ioperm(). Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/entry')
-rw-r--r--arch/x86/entry/common.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 3f8e22615812..9747876980b5 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -33,6 +33,7 @@
#include <asm/cpufeature.h>
#include <asm/fpu/api.h>
#include <asm/nospec-branch.h>
+#include <asm/io_bitmap.h>
#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>
@@ -196,6 +197,9 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs)
/* Reload ti->flags; we may have rescheduled above. */
cached_flags = READ_ONCE(ti->flags);
+ if (unlikely(cached_flags & _TIF_IO_BITMAP))
+ tss_update_io_bitmap();
+
fpregs_assert_state_consistent();
if (unlikely(cached_flags & _TIF_NEED_FPU_LOAD))
switch_fpu_return();