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b61e1f3281
Move the in-kernel kprobes insn page to text segment. Rationale: having that page in rw data segment is suboptimal, since as soon as a kprobe is set, this will split the 1:1 kernel mapping for a single page which get new permissions. Note: there is always at least one kprobe present for the kretprobe trampoline; so the mapping will always be split into smaller 4k mappings because of this. Moving the kprobes insn page into text segment makes sure that the page is mapped RO/X in any case, and avoids that the 1:1 mapping is split. The kprobe insn_page is defined as a dummy function which is filled with "br %r14" instructions. Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
22 lines
746 B
ArmAsm
22 lines
746 B
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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#include <linux/linkage.h>
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/*
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* insn_page is a special 4k aligned dummy function for kprobes.
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* It will contain all kprobed instructions that are out-of-line executed.
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* The page must be within the kernel image to guarantee that the
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* out-of-line instructions are within 2GB distance of their original
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* location. Using a dummy function ensures that the insn_page is within
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* the text section of the kernel and mapped read-only/executable from
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* the beginning on, thus avoiding to split large mappings if the page
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* would be in the data section instead.
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*/
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.section .kprobes.text, "ax"
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.align 4096
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ENTRY(kprobes_insn_page)
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.rept 2048
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.word 0x07fe
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.endr
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ENDPROC(kprobes_insn_page)
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.previous
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