powerpc/ftrace: Refactor ftrace_modify_code()
Split up ftrace_modify_code() into a few helpers for future use. Also update error messages accordingly. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/a8daa49712b44ff539e6c22a2ea649a540386798.1687166935.git.naveen@kernel.org
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@ -50,32 +50,39 @@ ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
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return op;
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}
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static inline int
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ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
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static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op)
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{
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ppc_inst_t replaced;
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/*
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* Note:
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* We are paranoid about modifying text, as if a bug was to happen, it
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* could cause us to read or write to someplace that could cause harm.
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* Carefully read and modify the code with probe_kernel_*(), and make
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* sure what we read is what we expected it to be before modifying it.
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*/
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/* read the text we want to modify */
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if (copy_inst_from_kernel_nofault(&replaced, (void *)ip))
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if (copy_inst_from_kernel_nofault(op, (void *)ip)) {
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pr_err("0x%lx: fetching instruction failed\n", ip);
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return -EFAULT;
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/* Make sure it is what we expect it to be */
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if (!ppc_inst_equal(replaced, old)) {
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pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip,
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ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old));
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return -EINVAL;
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}
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/* replace the text with the new text */
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return patch_instruction((u32 *)ip, new);
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return 0;
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}
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static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst)
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{
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ppc_inst_t op;
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int ret;
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ret = ftrace_read_inst(ip, &op);
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if (!ret && !ppc_inst_equal(op, inst)) {
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pr_err("0x%lx: expected (%08lx) != found (%08lx)\n",
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ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op));
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ret = -EINVAL;
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}
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return ret;
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}
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static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
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{
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int ret = ftrace_validate_inst(ip, old);
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if (!ret)
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ret = patch_instruction((u32 *)ip, new);
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return ret;
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}
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/*
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