[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v3 1/5] xen: introduce xen,enhanced dom0less property
Hi Stefano, On 23/03/2022 00:08, Stefano Stabellini wrote: On Sat, 29 Jan 2022, Julien Grall wrote:diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c index 6931c022a2..9144d6c0b6 100644 --- a/xen/arch/arm/domain_build.c +++ b/xen/arch/arm/domain_build.c @@ -2963,6 +2963,7 @@ static int __init construct_domU(struct domain *d, const struct dt_device_node *node) { struct kernel_info kinfo = {}; + const char *dom0less_enhanced; int rc; u64 mem; @@ -2978,6 +2979,12 @@ static int __init construct_domU(struct domain *d, kinfo.vpl011 = dt_property_read_bool(node, "vpl011"); + rc = dt_property_read_string(node, "xen,enhanced", &dom0less_enhanced); + if ( rc == -EILSEQ ||I think the use an -EILSEQ wants an explanation. In a previous version, you wrote that the value would be returned when: fdt set /chosen/domU0 xen,enhanced But it is not clear why. Can you print pp->value, pp->length, strnlen(..) when this happens?I added in dt_property_read_string: printk("DEBUG %s %d value=%s value[0]=%d length=%u len=%lu\n",__func__,__LINE__,(char*)pp->value, *((char*)pp->value),pp->length, strlen(pp->value)); This is the output: (XEN) DEBUG dt_property_read_string 205 value= value[0]=0 length=0 len=0 Thanks posting the log!For convenience, I am copying the comment on top of dt_property_read_string() prototype: * Search for a property in a device tree node and retrieve a null * terminated string value (pointer to data, not a copy). Returns 0 on * success, -EINVAL if the property does not exist, -ENODATA if property * doest not have value, and -EILSEQ if the string is not * null-terminated with the length of the property data.Per your log, the length is NULL so I would have assumed -ENODATA would be returned. Looking at the implementation: const struct dt_property *pp = dt_find_property(np, propname, NULL); if ( !pp ) return -EINVAL; if ( !pp->value ) return -ENODATA; if ( strnlen(pp->value, pp->length) >= pp->length ) return -EILSEQ;We consider that the property when pp->value is NULL. However, AFAICT, we never set pp->value to NULL (see unflatten_dt_node()). So I think there is a bug in the implementation. I would keep the check !pp->value (for hardening purpose) and also return -ENODATA when !pp->length. Most of our device-tree code is from Linux. Looking at v5.17, the bug seems to be present there too. This would want to be fixed there too. Cheers, -- Julien Grall
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