| Message ID | a8daa49712b44ff539e6c22a2ea649a540386798.1687166935.git.naveen@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | f4fcbf2e093e25a7faa8a3c2a5097524114e9547 |
| Headers | show |
| Series | powerpc/ftrace: refactor and add support for -fpatchable-function-entry | expand |
Le 19/06/2023 à 11:47, Naveen N Rao a écrit : > 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> > --- > arch/powerpc/kernel/trace/ftrace.c | 51 +++++++++++++++++------------- > 1 file changed, 29 insertions(+), 22 deletions(-) > > diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c > index 913c7aa63d3fa3..ef4e49c2c37781 100644 > --- a/arch/powerpc/kernel/trace/ftrace.c > +++ b/arch/powerpc/kernel/trace/ftrace.c > @@ -50,32 +50,39 @@ ftrace_call_replace(unsigned long ip, unsigned long addr, int link) > return op; > } > > -static inline int > -ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) > +static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op) > { > - ppc_inst_t replaced; > - > - /* > - * Note: > - * We are paranoid about modifying text, as if a bug was to happen, it > - * could cause us to read or write to someplace that could cause harm. > - * Carefully read and modify the code with probe_kernel_*(), and make > - * sure what we read is what we expected it to be before modifying it. > - */ > - > - /* read the text we want to modify */ > - if (copy_inst_from_kernel_nofault(&replaced, (void *)ip)) > + if (copy_inst_from_kernel_nofault(op, (void *)ip)) { > + pr_err("0x%lx: fetching instruction failed\n", ip); > return -EFAULT; > - > - /* Make sure it is what we expect it to be */ > - if (!ppc_inst_equal(replaced, old)) { > - pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip, > - ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old)); > - return -EINVAL; > } > > - /* replace the text with the new text */ > - return patch_instruction((u32 *)ip, new); > + return 0; > +} > + > +static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst) > +{ > + ppc_inst_t op; > + int ret; > + > + ret = ftrace_read_inst(ip, &op); > + if (!ret && !ppc_inst_equal(op, inst)) { > + pr_err("0x%lx: expected (%08lx) != found (%08lx)\n", > + ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op)); > + ret = -EINVAL; > + } > + > + return ret; > +} > + > +static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) > +{ > + int ret = ftrace_validate_inst(ip, old); > + > + if (!ret) > + ret = patch_instruction((u32 *)ip, new); > + > + return ret; > } > > /*
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index 913c7aa63d3fa3..ef4e49c2c37781 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -50,32 +50,39 @@ ftrace_call_replace(unsigned long ip, unsigned long addr, int link) return op; } -static inline int -ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) +static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op) { - ppc_inst_t replaced; - - /* - * Note: - * We are paranoid about modifying text, as if a bug was to happen, it - * could cause us to read or write to someplace that could cause harm. - * Carefully read and modify the code with probe_kernel_*(), and make - * sure what we read is what we expected it to be before modifying it. - */ - - /* read the text we want to modify */ - if (copy_inst_from_kernel_nofault(&replaced, (void *)ip)) + if (copy_inst_from_kernel_nofault(op, (void *)ip)) { + pr_err("0x%lx: fetching instruction failed\n", ip); return -EFAULT; - - /* Make sure it is what we expect it to be */ - if (!ppc_inst_equal(replaced, old)) { - pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip, - ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old)); - return -EINVAL; } - /* replace the text with the new text */ - return patch_instruction((u32 *)ip, new); + return 0; +} + +static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst) +{ + ppc_inst_t op; + int ret; + + ret = ftrace_read_inst(ip, &op); + if (!ret && !ppc_inst_equal(op, inst)) { + pr_err("0x%lx: expected (%08lx) != found (%08lx)\n", + ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op)); + ret = -EINVAL; + } + + return ret; +} + +static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) +{ + int ret = ftrace_validate_inst(ip, old); + + if (!ret) + ret = patch_instruction((u32 *)ip, new); + + return ret; } /*
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> --- arch/powerpc/kernel/trace/ftrace.c | 51 +++++++++++++++++------------- 1 file changed, 29 insertions(+), 22 deletions(-)