diff options
| -rw-r--r-- | arch/x86/kernel/unwind_orc.c | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c index 33b66b5c5aec..72b997eaa1fc 100644 --- a/arch/x86/kernel/unwind_orc.c +++ b/arch/x86/kernel/unwind_orc.c @@ -82,9 +82,9 @@ static struct orc_entry *orc_find(unsigned long ip); * But they are copies of the ftrace entries that are static and * defined in ftrace_*.S, which do have orc entries. * - * If the undwinder comes across a ftrace trampoline, then find the + * If the unwinder comes across a ftrace trampoline, then find the * ftrace function that was used to create it, and use that ftrace - * function's orc entrie, as the placement of the return code in + * function's orc entry, as the placement of the return code in * the stack will be identical. */ static struct orc_entry *orc_ftrace_find(unsigned long ip) @@ -128,6 +128,16 @@ static struct orc_entry null_orc_entry = { .type = ORC_TYPE_CALL }; +/* Fake frame pointer entry -- used as a fallback for generated code */ +static struct orc_entry orc_fp_entry = { + .type = ORC_TYPE_CALL, + .sp_reg = ORC_REG_BP, + .sp_offset = 16, + .bp_reg = ORC_REG_PREV_SP, + .bp_offset = -16, + .end = 0, +}; + static struct orc_entry *orc_find(unsigned long ip) { static struct orc_entry *orc; @@ -392,8 +402,16 @@ bool unwind_next_frame(struct unwind_state *state) * calls and calls to noreturn functions. */ orc = orc_find(state->signal ? state->ip : state->ip - 1); - if (!orc) - goto err; + if (!orc) { + /* + * As a fallback, try to assume this code uses a frame pointer. + * This is useful for generated code, like BPF, which ORC + * doesn't know about. This is just a guess, so the rest of + * the unwind is no longer considered reliable. + */ + orc = &orc_fp_entry; + state->error = true; + } /* End-of-stack check for kernel threads: */ if (orc->sp_reg == ORC_REG_UNDEFINED) { |