Hi Laurent,
Laurent Dufour <lduf...@linux.ibm.com> writes:
> +/*
> + * PAPR defines, in section "7.3.16 System Parameters Option", the token 55
> to
> + * read the LPAR name.
> + */
> +#define SPLPAR_LPAR_NAME_TOKEN 55
> +static void read_lpar_name(struct seq_file *m)
> +{
> + int rc, len, token;
> + union {
> + char raw_buffer[RTAS_DATA_BUF_SIZE];
> + struct {
> + __be16 len;
This:
> + char name[RTAS_DATA_BUF_SIZE-2];
^^^^^^
should be 4000, not (4K - 2), according to PAPR (it's weird and I don't
know the reason).
> + };
> + } *local_buffer;
> +
> + token = rtas_token("ibm,get-system-parameter");
> + if (token == RTAS_UNKNOWN_SERVICE)
> + return;
> +
> + local_buffer = kmalloc(sizeof(*local_buffer), GFP_KERNEL);
> + if (!local_buffer)
> + return;
> +
> + do {
> + spin_lock(&rtas_data_buf_lock);
> + memset(rtas_data_buf, 0, RTAS_DATA_BUF_SIZE);
> + rc = rtas_call(token, 3, 1, NULL, SPLPAR_LPAR_NAME_TOKEN,
> + __pa(rtas_data_buf), RTAS_DATA_BUF_SIZE);
> + if (!rc)
> + memcpy(local_buffer->raw_buffer, rtas_data_buf,
> + RTAS_DATA_BUF_SIZE);
> + spin_unlock(&rtas_data_buf_lock);
> + } while (rtas_busy_delay(rc));
> +
> + if (rc != 0) {
> + pr_err_once(
> + "%s %s Error calling get-system-parameter (0x%x)\n",
> + __FILE__, __func__, rc);
The __FILE__ and __func__ in the message seem unnecessary, and rc should
be reported in decimal so the error meaning is apparent.
Is there a reasonable fallback for VMs where this parameter doesn't
exist? PowerVM partitions should always have it, but what do we want the
behavior to be on other hypervisors?
> + } else {
> + /* Force end of string */
> + len = be16_to_cpu(local_buffer->len);
> + if (len >= (RTAS_DATA_BUF_SIZE-2))
> + len = RTAS_DATA_BUF_SIZE-2;
Could use min() or clamp(), and it would be better to build the
expression using the value of sizeof(local_buffer->name).
> + local_buffer->name[len] = '\0';
If 'len' can be (RTAS_DATA_BUF_SIZE - 2), then this writes past the end
of the buffer, no?
