uprobes: Introduce copy_opcode(), kill read_opcode()
No functional changes, preparations.
1. Extract the kmap-and-memcpy code from read_opcode() into the
new trivial helper, copy_opcode(). The next patch will add
another user.
2. read_opcode() becomes really trivial, fold it into its single
caller, is_swbp_at_addr().
3. Remove "auprobe" argument from write_opcode(), it is not used
since f403072c6
.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
This commit is contained in:
parent
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@ -183,19 +183,25 @@ bool __weak is_swbp_insn(uprobe_opcode_t *insn)
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return *insn == UPROBE_SWBP_INSN;
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}
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static void copy_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *opcode)
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{
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void *kaddr = kmap_atomic(page);
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memcpy(opcode, kaddr + (vaddr & ~PAGE_MASK), UPROBE_SWBP_INSN_SIZE);
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kunmap_atomic(kaddr);
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}
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/*
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* NOTE:
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* Expect the breakpoint instruction to be the smallest size instruction for
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* the architecture. If an arch has variable length instruction and the
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* breakpoint instruction is not of the smallest length instruction
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* supported by that architecture then we need to modify read_opcode /
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* supported by that architecture then we need to modify is_swbp_at_addr and
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* write_opcode accordingly. This would never be a problem for archs that
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* have fixed length instructions.
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*/
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/*
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* write_opcode - write the opcode at a given virtual address.
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* @auprobe: arch breakpointing information.
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* @mm: the probed process address space.
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* @vaddr: the virtual address to store the opcode.
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* @opcode: opcode to be written at @vaddr.
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@ -206,8 +212,8 @@ bool __weak is_swbp_insn(uprobe_opcode_t *insn)
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* For mm @mm, write the opcode at @vaddr.
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* Return 0 (success) or a negative errno.
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*/
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static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
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unsigned long vaddr, uprobe_opcode_t opcode)
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static int write_opcode(struct mm_struct *mm, unsigned long vaddr,
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uprobe_opcode_t opcode)
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{
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struct page *old_page, *new_page;
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void *vaddr_old, *vaddr_new;
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@ -253,40 +259,9 @@ put_old:
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return ret;
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}
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/**
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* read_opcode - read the opcode at a given virtual address.
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* @mm: the probed process address space.
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* @vaddr: the virtual address to read the opcode.
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* @opcode: location to store the read opcode.
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*
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* Called with mm->mmap_sem held (for read and with a reference to
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* mm.
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*
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* For mm @mm, read the opcode at @vaddr and store it in @opcode.
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* Return 0 (success) or a negative errno.
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*/
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static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t *opcode)
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{
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struct page *page;
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void *vaddr_new;
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int ret;
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ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
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if (ret <= 0)
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return ret;
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vaddr_new = kmap_atomic(page);
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vaddr &= ~PAGE_MASK;
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memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE);
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kunmap_atomic(vaddr_new);
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put_page(page);
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return 0;
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}
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static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
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{
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struct page *page;
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uprobe_opcode_t opcode;
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int result;
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@ -300,14 +275,14 @@ static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
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goto out;
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}
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result = read_opcode(mm, vaddr, &opcode);
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if (result)
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result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
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if (result < 0)
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return result;
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out:
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if (is_swbp_insn(&opcode))
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return 1;
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return 0;
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copy_opcode(page, vaddr, &opcode);
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put_page(page);
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out:
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return is_swbp_insn(&opcode);
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}
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/**
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@ -321,7 +296,7 @@ out:
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*/
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int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
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{
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return write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN);
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return write_opcode(mm, vaddr, UPROBE_SWBP_INSN);
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}
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/**
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@ -345,7 +320,7 @@ set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long v
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if (result != 1)
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return result;
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return write_opcode(auprobe, mm, vaddr, *(uprobe_opcode_t *)auprobe->insn);
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return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn);
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}
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static int match_uprobe(struct uprobe *l, struct uprobe *r)
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