If a trap is encountered upon executing iretq from within doreti() the
hardware will ensure the stack pointer is aligned to a 16-byte boundary before saving the fault state on the stack. In the PTI case, handle this potential alignment adjustment by copying both frames independently while unwinding the stack in between. Reviewed by: kib Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D15183
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=332994
@ -341,6 +341,9 @@ page_cr2:
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* On the stack, we have the hardware interrupt frame to return
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* to usermode (faulted) and another frame with error code, for
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* fault. For PTI, copy both frames to the main thread stack.
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* Handle the potential 16-byte alignment adjustment incurred
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* during the second fault by copying both frames independently
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* while unwinding the stack in between.
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*/
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.macro PROTF_ENTRY name,trapno
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\name\()_pti_doreti:
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@ -351,7 +354,11 @@ page_cr2:
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movq %rax,%cr3
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movq PCPU(RSP0),%rax
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subq $2*PTI_SIZE-3*8,%rax /* no err, %rax, %rdx in faulted frame */
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MOVE_STACKS (PTI_SIZE / 4 - 3)
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MOVE_STACKS (PTI_SIZE / 8)
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addq $PTI_SIZE,%rax
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movq PTI_RSP(%rsp),%rsp
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MOVE_STACKS (PTI_SIZE / 8 - 3)
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subq $PTI_SIZE,%rax
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movq %rax,%rsp
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popq %rdx
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popq %rax
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