Hi, Oleg, On Sat, Jun 29, 2024 at 11:05 PM Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > > LoongArch defines UPROBE_SWBP_INSN as a function call and this breaks > arch_uprobe_trampoline() which uses it to initialize a static variable. > > Add the new "__builtin_constant_p" helper, __emit_break(), and redefine > the current users of larch_insn_gen_break() to use it. > > The patch adds check_emit_break() into kprobes.c and uprobes.c to test > this change. They can be removed if LoongArch boots at least once, but > otoh these 2 __init functions will be discarded by free_initmem(). > > Fixes: ff474a78cef5 ("uprobe: Add uretprobe syscall to speed up return probe") > Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx> > Closes: https://lore.kernel.org/all/20240614174822.GA1185149@thelio-3990X/ > Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> > --- > arch/loongarch/include/asm/inst.h | 3 +++ > arch/loongarch/include/asm/uprobes.h | 4 ++-- > arch/loongarch/kernel/kprobes.c | 12 ++++++++++-- > arch/loongarch/kernel/uprobes.c | 8 ++++++++ > 4 files changed, 23 insertions(+), 4 deletions(-) > > diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h > index c3993fd88aba..944482063f14 100644 > --- a/arch/loongarch/include/asm/inst.h > +++ b/arch/loongarch/include/asm/inst.h > @@ -532,6 +532,9 @@ static inline void emit_##NAME(union loongarch_instruction *insn, \ > > DEF_EMIT_REG0I15_FORMAT(break, break_op) > > +/* like emit_break(imm) but returns a constant expression */ > +#define __emit_break(imm) ((u32)((imm) | (break_op << 15))) > + > #define DEF_EMIT_REG0I26_FORMAT(NAME, OP) \ > static inline void emit_##NAME(union loongarch_instruction *insn, \ > int offset) \ > diff --git a/arch/loongarch/include/asm/uprobes.h b/arch/loongarch/include/asm/uprobes.h > index c8f59983f702..99a0d198927f 100644 > --- a/arch/loongarch/include/asm/uprobes.h > +++ b/arch/loongarch/include/asm/uprobes.h > @@ -9,10 +9,10 @@ typedef u32 uprobe_opcode_t; > #define MAX_UINSN_BYTES 8 > #define UPROBE_XOL_SLOT_BYTES MAX_UINSN_BYTES > > -#define UPROBE_SWBP_INSN larch_insn_gen_break(BRK_UPROBE_BP) > +#define UPROBE_SWBP_INSN __emit_break(BRK_UPROBE_BP) > #define UPROBE_SWBP_INSN_SIZE LOONGARCH_INSN_SIZE > > -#define UPROBE_XOLBP_INSN larch_insn_gen_break(BRK_UPROBE_XOLBP) > +#define UPROBE_XOLBP_INSN __emit_break(BRK_UPROBE_XOLBP) > > struct arch_uprobe { > unsigned long resume_era; > diff --git a/arch/loongarch/kernel/kprobes.c b/arch/loongarch/kernel/kprobes.c > index 17b040bd6067..78cfaac52748 100644 > --- a/arch/loongarch/kernel/kprobes.c > +++ b/arch/loongarch/kernel/kprobes.c > @@ -4,8 +4,16 @@ > #include <linux/preempt.h> > #include <asm/break.h> > > -#define KPROBE_BP_INSN larch_insn_gen_break(BRK_KPROBE_BP) > -#define KPROBE_SSTEPBP_INSN larch_insn_gen_break(BRK_KPROBE_SSTEPBP) > +#define KPROBE_BP_INSN __emit_break(BRK_KPROBE_BP) > +#define KPROBE_SSTEPBP_INSN __emit_break(BRK_KPROBE_SSTEPBP) > + > +static __init int check_emit_break(void) > +{ > + BUG_ON(KPROBE_BP_INSN != larch_insn_gen_break(BRK_KPROBE_BP)); > + BUG_ON(KPROBE_SSTEPBP_INSN != larch_insn_gen_break(BRK_KPROBE_SSTEPBP)); > + return 0; > +} > +arch_initcall(check_emit_break); > > DEFINE_PER_CPU(struct kprobe *, current_kprobe); > DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); > diff --git a/arch/loongarch/kernel/uprobes.c b/arch/loongarch/kernel/uprobes.c > index 87abc7137b73..90462d94c28f 100644 > --- a/arch/loongarch/kernel/uprobes.c > +++ b/arch/loongarch/kernel/uprobes.c > @@ -7,6 +7,14 @@ > > #define UPROBE_TRAP_NR UINT_MAX > > +static __init int check_emit_break(void) > +{ > + BUG_ON(UPROBE_SWBP_INSN != larch_insn_gen_break(BRK_UPROBE_BP)); > + BUG_ON(UPROBE_XOLBP_INSN != larch_insn_gen_break(BRK_UPROBE_XOLBP)); > + return 0; > +} > +arch_initcall(check_emit_break); Do you mind if I remove the runtime checking after Tiezhu tests the correctness? Huacai > + > int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, > struct mm_struct *mm, unsigned long addr) > { > -- > 2.25.1.362.g51ebf55 > >