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author | Andy Lutomirski <luto@kernel.org> | |
Sun, 14 Oct 2018 18:38:18 +0000 (11:38 -0700) | ||
committer | Ingo Molnar <mingo@kernel.org> | |
Wed, 17 Oct 2018 10:30:27 +0000 (12:30 +0200) |
Commit:
16561f27f94e ("x86/entry: Add some paranoid entry/exit CR3 handling comments")
... added some comments. This improves them a bit:
- When I first read the new comments, it was unclear to me whether
they were referring to the case where paranoid_entry interrupted
other entry code or where paranoid_entry was itself interrupted.
Clarify it.
- Remove the EBX comment. We no longer use EBX as a SWAPGS
indicator.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/c47daa1888dc2298e7e1d3f82bd76b776ea33393.1539542111.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
16561f27f94e ("x86/entry: Add some paranoid entry/exit CR3 handling comments")
... added some comments. This improves them a bit:
- When I first read the new comments, it was unclear to me whether
they were referring to the case where paranoid_entry interrupted
other entry code or where paranoid_entry was itself interrupted.
Clarify it.
- Remove the EBX comment. We no longer use EBX as a SWAPGS
indicator.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/c47daa1888dc2298e7e1d3f82bd76b776ea33393.1539542111.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/entry/entry_64.S | patch | blob | history |
index 1d9b4a300c8ceda8970fed215a8bb55e46af6de7..f95dcb209fdffce611edeb0fa79dc2cd83bd9418 100644 (file)
1:
/*
* Always stash CR3 in %r14. This value will be restored,
- * verbatim, at exit. Needed if kernel is interrupted
- * after switching to the user CR3 value but before
- * returning to userspace.
+ * verbatim, at exit. Needed if paranoid_entry interrupted
+ * another entry that already switched to the user CR3 value
+ * but has not yet returned to userspace.
*
* This is also why CS (stashed in the "iret frame" by the
* hardware at entry) can not be used: this may be a return
- * to kernel code, but with a user CR3 value. The %ebx flag
- * for SWAPGS is also unusable for CR3 because there is a
- * window with a user GS and a kernel CR3.
+ * to kernel code, but with a user CR3 value.
*/
SAVE_AND_SWITCH_TO_KERNEL_CR3 scratch_reg=%rax save_reg=%r14