s390/kprobes: make insn pages read-only (6c6687a4) · Commits · 戴 / test

arch/s390/kernel/kprobes.c

+39 −18

Original line number	Diff line number	Diff line
		@@ -7,6 +7,7 @@
		* s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
		*/

		#include <linux/moduleloader.h>
		#include <linux/kprobes.h>
		#include <linux/ptrace.h>
		#include <linux/preempt.h>
		@@ -32,17 +33,33 @@ DEFINE_INSN_CACHE_OPS(s390_insn);
		static int insn_page_in_use;
		static char insn_page[PAGE_SIZE] __aligned(PAGE_SIZE);

		void *alloc_insn_page(void)
		{
		void *page;

		page = module_alloc(PAGE_SIZE);
		if (!page)
		return NULL;
		__set_memory((unsigned long) page, 1, SET_MEMORY_RO \| SET_MEMORY_X);
		return page;
		}

		void free_insn_page(void *page)
		{
		module_memfree(page);
		}

		static void *alloc_s390_insn_page(void)
		{
		if (xchg(&insn_page_in_use, 1) == 1)
		return NULL;
		set_memory_x((unsigned long) &insn_page, 1);
		__set_memory((unsigned long) &insn_page, 1, SET_MEMORY_RO \| SET_MEMORY_X);
		return &insn_page;
		}

		static void free_s390_insn_page(void *page)
		{
		set_memory_nx((unsigned long) page, 1);
		__set_memory((unsigned long) page, 1, SET_MEMORY_RW \| SET_MEMORY_NX);
		xchg(&insn_page_in_use, 0);
		}

		@@ -56,25 +73,29 @@ struct kprobe_insn_cache kprobe_s390_insn_slots = {

		static void copy_instruction(struct kprobe *p)
		{
		kprobe_opcode_t insn[MAX_INSN_SIZE];
		s64 disp, new_disp;
		u64 addr, new_addr;
		unsigned int len;

		memcpy(p->ainsn.insn, p->addr, insn_length(*p->addr >> 8));
		p->opcode = p->ainsn.insn[0];
		if (!probe_is_insn_relative_long(p->ainsn.insn))
		return;
		len = insn_length(*p->addr >> 8);
		memcpy(&insn, p->addr, len);
		p->opcode = insn[0];
		if (probe_is_insn_relative_long(&insn[0])) {
		/*
		* For pc-relative instructions in RIL-b or RIL-c format patch the
		* RI2 displacement field. We have already made sure that the insn
		* slot for the patched instruction is within the same 2GB area
		* as the original instruction (either kernel image or module area).
		* Therefore the new displacement will always fit.
		* For pc-relative instructions in RIL-b or RIL-c format patch
		* the RI2 displacement field. We have already made sure that
		* the insn slot for the patched instruction is within the same
		* 2GB area as the original instruction (either kernel image or
		* module area). Therefore the new displacement will always fit.
		*/
		disp = (s32 )&p->ainsn.insn[1];
		disp = (s32 )&insn[1];
		addr = (u64)(unsigned long)p->addr;
		new_addr = (u64)(unsigned long)p->ainsn.insn;
		new_disp = ((addr + (disp * 2)) - new_addr) / 2;
		(s32 )&p->ainsn.insn[1] = new_disp;
		(s32 )&insn[1] = new_disp;
		}
		s390_kernel_write(p->ainsn.insn, &insn, len);
		}
		NOKPROBE_SYMBOL(copy_instruction);

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