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Because when the landing pad is activated, if the uprobe point is set at the lpad instruction at the beginning of a function, the system triggers a software-check exception instead of an ebreak exception due to the exception priority, then uprobe can't work successfully. Co-developed-by: Deepak Gupta Signed-off-by: Deepak Gupta Signed-off-by: Zong Li --- Changed in v2: - Handle uprobe events only in the forward CFI case - Move uprobe handling from do_trap_software_check to handle_user_cfi_viola= tion arch/riscv/kernel/traps.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index d7b5fd576011..3aa5ecda29a8 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -369,17 +369,25 @@ void do_trap_ecall_u(struct pt_regs *regs) /* handle cfi violations */ bool handle_user_cfi_violation(struct pt_regs *regs) { - bool ret =3D false; unsigned long tval =3D csr_read(CSR_TVAL); - - if ((tval =3D=3D CFI_TVAL_FCFI_CODE && cpu_supports_indirect_br_lp_instr(= )) || - (tval =3D=3D CFI_TVAL_BCFI_CODE && cpu_supports_shadow_stack())) { + bool is_fcfi =3D (tval =3D=3D CFI_TVAL_FCFI_CODE && cpu_supports_indirect= _br_lp_instr()); + bool is_bcfi =3D (tval =3D=3D CFI_TVAL_BCFI_CODE && cpu_supports_shadow_s= tack()); + + /* + * Handle uprobe event frist. The probe point can be a valid target + * of indirect jumps or calls, in this case, forward cfi violation + * will be triggered instead of breakpoint exception. + */ + if (is_fcfi && probe_breakpoint_handler(regs)) + return true; + + if (is_fcfi || is_bcfi) { do_trap_error(regs, SIGSEGV, SEGV_CPERR, regs->epc, "Oops - control flow violation"); - ret =3D true; + return true; } =20 - return ret; + return false; } =20 /* --=20 2.17.1