On 23/06/2020 14.07, Alan Maguire wrote:
> diff --git a/include/linux/printk.h b/include/linux/printk.h
> index fc8f03c..8f8f5d2 100644
> --- a/include/linux/printk.h
> +++ b/include/linux/printk.h
> @@ -618,4 +618,20 @@ static inline void print_hex_dump_debug(const char
> *prefix_str, int prefix_type,
> #define print_hex_dump_bytes(prefix_str, prefix_type, buf, len) \
> print_hex_dump_debug(prefix_str, prefix_type, 16, 1, buf, len, true)
>
> +/**
> + * struct btf_ptr is used for %pT (typed pointer) display; the
> + * additional type string/BTF id are used to render the pointer
> + * data as the appropriate type.
> + */
> +struct btf_ptr {
> + void *ptr;
> + const char *type;
> + u32 id;
> +};
> +
> +#define BTF_PTR_TYPE(ptrval, typeval) \
> + (&((struct btf_ptr){.ptr = ptrval, .type = #typeval}))
> +
> +#define BTF_PTR_ID(ptrval, idval) \
> + (&((struct btf_ptr){.ptr = ptrval, .id = idval}))
Isn't there some better place to put this than printk.h? Anyway, you
probably want the ptr member to be "const void*", to avoid "... discards
const qualifier" warnings when somebody happens to have a "const struct
foobar *".
> #endif
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 259e558..c0d209d 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -44,6 +44,7 @@
> #ifdef CONFIG_BLOCK
> #include <linux/blkdev.h>
> #endif
> +#include <linux/btf.h>
>
> #include "../mm/internal.h" /* For the trace_print_flags arrays */
>
> @@ -2092,6 +2093,87 @@ char *fwnode_string(char *buf, char *end, struct
> fwnode_handle *fwnode,
> return widen_string(buf, buf - buf_start, end, spec);
> }
>
> +#define btf_modifier_flag(c) (c == 'c' ? BTF_SHOW_COMPACT : \
> + c == 'N' ? BTF_SHOW_NONAME : \
> + c == 'x' ? BTF_SHOW_PTR_RAW : \
> + c == 'u' ? BTF_SHOW_UNSAFE : \
> + c == '0' ? BTF_SHOW_ZERO : 0)
> +
> +static noinline_for_stack
> +char *btf_string(char *buf, char *end, void *ptr, struct printf_spec spec,
> + const char *fmt)
> +{
> + struct btf_ptr *bp = (struct btf_ptr *)ptr;
> + u8 btf_kind = BTF_KIND_TYPEDEF;
> + const struct btf_type *t;
> + const struct btf *btf;
> + char *buf_start = buf;
> + const char *btf_type;
> + u64 flags = 0, mod;
> + s32 btf_id;
> +
> + if (check_pointer(&buf, end, ptr, spec))
> + return buf;
> +
> + if (check_pointer(&buf, end, bp->ptr, spec))
> + return buf;
> +
> + while (isalnum(*fmt)) {
> + mod = btf_modifier_flag(*fmt);
> + if (!mod)
> + break;
> + flags |= mod;
> + fmt++;
> + }
> +
> + btf = bpf_get_btf_vmlinux();
AFAICT, this function is only compiled if CONFIG_BPF=y and
CONFIG_BPF_SYSCALL=y, and I don't see any static inline stub defined
anywhere. Have you built the kernel with one or both of those turned off?
Rasmus
