From: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> commit 531936dee53e471a3ec668de3c94ca357f54b7e8 upstream. The maximum number of load/store watchpoints and fetch instruction watchpoints is 14 each according to LoongArch Reference Manual, so extend the maximum number of watchpoints from 8 to 14 for ptrace. By the way, just simply change 8 to 14 for the definition in struct user_watch_state at the beginning, but it may corrupt uapi, then add a new struct user_watch_state_v2 directly. As far as I can tell, the only users for this struct in the userspace are GDB and LLDB, there are no any problems of software compatibility between the application and kernel according to the analysis. The compatibility problem has been considered while developing and testing. When the applications in the userspace get watchpoint state, the length will be specified which is no bigger than the sizeof struct user_watch_state or user_watch_state_v2, the actual length is assigned as the minimal value of the application and kernel in the generic code of ptrace: kernel/ptrace.c: ptrace_regset(): kiov->iov_len = min(kiov->iov_len, (__kernel_size_t) (regset->n * regset->size)); if (req == PTRACE_GETREGSET) return copy_regset_to_user(task, view, regset_no, 0, kiov->iov_len, kiov->iov_base); else return copy_regset_from_user(task, view, regset_no, 0, kiov->iov_len, kiov->iov_base); For example, there are four kind of combinations, all of them work well. (1) "older kernel + older gdb", the actual length is 8+(8+8+4+4)*8=200; (2) "newer kernel + newer gdb", the actual length is 8+(8+8+4+4)*14=344; (3) "older kernel + newer gdb", the actual length is 8+(8+8+4+4)*8=200; (4) "newer kernel + older gdb", the actual length is 8+(8+8+4+4)*8=200. Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#control-and-status-registers-related-to-watchpoints Cc: stable@xxxxxxxxxxxxxxx Fixes: 1a69f7a161a7 ("LoongArch: ptrace: Expose hardware breakpoints to debuggers") Reviewed-by: WANG Xuerui <git@xxxxxxxxxx> Reviewed-by: Xi Ruoyao <xry111@xxxxxxxxxxx> Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/loongarch/include/uapi/asm/ptrace.h | 10 ++++++++++ arch/loongarch/kernel/ptrace.c | 6 +++--- 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/loongarch/include/uapi/asm/ptrace.h b/arch/loongarch/include/uapi/asm/ptrace.h index ac915f841650..aafb3cd9e943 100644 --- a/arch/loongarch/include/uapi/asm/ptrace.h +++ b/arch/loongarch/include/uapi/asm/ptrace.h @@ -72,6 +72,16 @@ struct user_watch_state { } dbg_regs[8]; }; +struct user_watch_state_v2 { + uint64_t dbg_info; + struct { + uint64_t addr; + uint64_t mask; + uint32_t ctrl; + uint32_t pad; + } dbg_regs[14]; +}; + #define PTRACE_SYSEMU 0x1f #define PTRACE_SYSEMU_SINGLESTEP 0x20 diff --git a/arch/loongarch/kernel/ptrace.c b/arch/loongarch/kernel/ptrace.c index 19dc6eff45cc..5e2402cfcab0 100644 --- a/arch/loongarch/kernel/ptrace.c +++ b/arch/loongarch/kernel/ptrace.c @@ -720,7 +720,7 @@ static int hw_break_set(struct task_struct *target, unsigned int note_type = regset->core_note_type; /* Resource info */ - offset = offsetof(struct user_watch_state, dbg_regs); + offset = offsetof(struct user_watch_state_v2, dbg_regs); user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf, 0, offset); /* (address, mask, ctrl) registers */ @@ -920,7 +920,7 @@ static const struct user_regset loongarch64_regsets[] = { #ifdef CONFIG_HAVE_HW_BREAKPOINT [REGSET_HW_BREAK] = { .core_note_type = NT_LOONGARCH_HW_BREAK, - .n = sizeof(struct user_watch_state) / sizeof(u32), + .n = sizeof(struct user_watch_state_v2) / sizeof(u32), .size = sizeof(u32), .align = sizeof(u32), .regset_get = hw_break_get, @@ -928,7 +928,7 @@ static const struct user_regset loongarch64_regsets[] = { }, [REGSET_HW_WATCH] = { .core_note_type = NT_LOONGARCH_HW_WATCH, - .n = sizeof(struct user_watch_state) / sizeof(u32), + .n = sizeof(struct user_watch_state_v2) / sizeof(u32), .size = sizeof(u32), .align = sizeof(u32), .regset_get = hw_break_get, -- 2.48.1 Patches currently in stable-queue which might be from yangtiezhu@xxxxxxxxxxx are queue-6.6/loongarch-extend-the-maximum-number-of-watchpoints.patch queue-6.6/mips-math-emu-fix-emulation-of-the-prefx-instruction.patch
