Messages in this thread | | | From | Lai Jiangshan <> | Date | Mon, 11 Apr 2022 19:48:48 +0800 | Subject | Re: [PATCH V4 2/7] x86/entry: Switch the stack after error_entry() returns |
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On Mon, Apr 11, 2022 at 5:35 PM Borislav Petkov <bp@alien8.de> wrote: > > On Fri, Mar 18, 2022 at 10:30:11PM +0800, Lai Jiangshan wrote: > > From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
> > > Switching to the stack after error_entry() makes the code simpler and > > intuitive. > > > > The behavior/logic is unchanged: > > 1) (opt) feed fixup_bad_iret() with the pt_regs pushed by ASM code > > opt?
I meant it as optional.
I will rewrite it as
1) feed fixup_bad_iret() with the pt_regs pushed by the ASM code if it is a fault caused by bad IRET.
> > > 2) (opt) fixup_bad_iret() moves the partial pt_regs up > > 3) feed sync_regs() with the pt_regs pushed by ASM code or returned > > by fixup_bad_iret() > > 4) sync_regs() copies the whole pt_regs to kernel stack if needed > > 5) after error_entry() and switching %rsp, it is in kernel stack with > > the pt_regs
> > > After this change, error_entry() will not do fancy things with the stack > > except when in the prolog which will be fixed in the next patch ("move > > PUSH_AND_CLEAR_REGS out of error_entry"). This patch and the next patch > > "This patch" is tautology, as already said. > > There's no "next patch" in git. > > > can't be swapped because the next patch relies on this patch's stopping > > fiddling with the return-address of error_entry(), otherwise the objtool > > would complain. > > If that is the case, then those two should me merged into one!
This patch moves the epilog (switching stack) of error_entry() out of error_entry(). The next patch moves the prolog (pushing pt_regs) out of error_entry(). They can be separated patches.
I don't think anything wrong if the order of these two patches is swapped. Peter Z asked info about the ordering of other patches and I tried moving the next patch up and saw the complaint from the objtool.
I wanted to explain the ordering of the patches. This explanation should be put in the cover letter instead of in the commit message.
Thanks Lai
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