Messages in this thread | | | From | Lai Jiangshan <> | Subject | [PATCH 0/5] x86/entry: simply stack switching when exception on userspace | Date | Wed, 27 May 2020 07:31:02 +0000 |
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7f2590a110b8("x86/entry/64: Use a per-CPU trampoline stack for IDT entries") has resulted that when exception on userspace, the kernel (error_entry) always push the pt_regs to entry stack(sp0), and then copy them to the kernel stack.
This is a hot path (for example page fault) and interrupt_entry directly switches to kernel stack and pushes pt_regs to kernel stack. We should do it for error_entry. This is the job of patch1,2.
Patch 3-5 simply stack switching for .Lerror_bad_iret by just doing all the work in one function (fixup_bad_iret()).
The patch set is based on tip/master (c021d3d8fe45) (Mon May 25).
The diffstat is "66 insertions(+), 66 deletions(-)", but actually it mainly adds comments and deletes code.
Cc: Andy Lutomirski <luto@kernel.org>, Cc: Thomas Gleixner <tglx@linutronix.de>, Cc: Ingo Molnar <mingo@redhat.com>, Cc: Borislav Petkov <bp@alien8.de>, Cc: x86@kernel.org, Cc: "H. Peter Anvin" <hpa@zytor.com>, Cc: Peter Zijlstra <peterz@infradead.org>, Cc: Alexandre Chartre <alexandre.chartre@oracle.com>, Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Jann Horn <jannh@google.com>, Cc: Dave Hansen <dave.hansen@linux.intel.com>
Lai Jiangshan (5): x86/entry: introduce macro idtentry_swapgs_and_switch_to_kernel_stack x86/entry: avoid calling into sync_regs() when entering from userspace x86/entry: directly switch to kernel stack when .Lerror_bad_iret x86/entry: remove unused sync_regs() x86/entry: don't copy to tmp in fixup_bad_iret
arch/x86/entry/entry_64.S | 89 ++++++++++++++++++++---------------- arch/x86/include/asm/traps.h | 1 - arch/x86/kernel/traps.c | 42 +++++++---------- 3 files changed, 66 insertions(+), 66 deletions(-)
-- 2.20.1
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