On 03/02/2015 01:49 PM, Tyrel Datwyler wrote: > On 03/01/2015 09:20 PM, Cyril Bur wrote: >> On Fri, 2015-02-27 at 18:24 -0800, Tyrel Datwyler wrote: >>> We currently use the device tree update code in the kernel after resuming >>> from a suspend operation to re-sync the kernels view of the device tree with >>> that of the hypervisor. The code as it stands is not endian safe as it >>> relies >>> on parsing buffers returned by RTAS calls that thusly contains data in big >>> endian format. >>> >>> This patch annotates variables and structure members with __be types as well >>> as performing necessary byte swaps to cpu endian for data that needs to be >>> parsed. >>> >>> Signed-off-by: Tyrel Datwyler <tyr...@linux.vnet.ibm.com> >>> --- >>> arch/powerpc/platforms/pseries/mobility.c | 36 >>> ++++++++++++++++--------------- >>> 1 file changed, 19 insertions(+), 17 deletions(-) >>> >>> diff --git a/arch/powerpc/platforms/pseries/mobility.c >>> b/arch/powerpc/platforms/pseries/mobility.c >>> index 29e4f04..0b1f70e 100644 >>> --- a/arch/powerpc/platforms/pseries/mobility.c >>> +++ b/arch/powerpc/platforms/pseries/mobility.c >>> @@ -25,10 +25,10 @@ >>> static struct kobject *mobility_kobj; >>> >>> struct update_props_workarea { >>> - u32 phandle; >>> - u32 state; >>> - u64 reserved; >>> - u32 nprops; >>> + __be32 phandle; >>> + __be32 state; >>> + __be64 reserved; >>> + __be32 nprops; >>> } __packed; >>> >>> #define NODE_ACTION_MASK 0xff000000 >>> @@ -127,7 +127,7 @@ static int update_dt_property(struct device_node *dn, >>> struct property **prop, >>> return 0; >>> } >>> >>> -static int update_dt_node(u32 phandle, s32 scope) >>> +static int update_dt_node(__be32 phandle, s32 scope) >>> { >> >> On line 153 of this function: >> dn = of_find_node_by_phandle(phandle); >> >> You're passing a __be32 to device tree code, if we can treat the phandle >> as a opaque value returned to us from the rtas call and pass it around >> like that then all good.
After digging deeper the device_node->phandle is stored in cpu endian under the covers. So, for the of_find_node_by_phandle() we do need to convert the phandle to cpu endian first. It appears I got lucky with the update fixing the observed RMC issue because the phandle for the root node seems to always be 0xffffffff. -Tyrel > > Yes, of_find_node_by_phandle directly compares phandle passed in against > the handle stored in each device_node when searching for a matching > node. Since, the device tree is big endian it follows that the big > endian phandle received in the rtas buffer needs no conversion. > > Further, we need to pass the phandle to ibm,update-properties in the > work area which is also required to be big endian. So, again it seemed > that converting to cpu endian was a waste of effort just to convert it > back to big endian. > >> Its also hard to be sure if these need to be BE and have always been >> that way because we've always run BE so they've never actually wanted >> CPU endian its just that CPU endian has always been BE (I think I >> started rambling...) >> >> Just want to check that *not* converting them is done on purpose. > > Yes, I explicitly did not convert them on purpose. As mentioned above we > need phandle in BE for the ibm,update-properties rtas work area. > Similarly, drc_index needs to be in BE for the ibm,configure-connector > rtas work area. Outside, of that we do no other manipulation of those > values. > >> >> And having read on, I'm assuming the answer is yes since this >> observation is true for your changes which affect: >> delete_dt_node() >> update_dt_node() >> add_dt_node() >> Worth noting that you didn't change the definition of delete_dt_node() > > You are correct. Oversight. I will fix that as it should generate a > sparse complaint. > > -Tyrel > >> >> I'll have a look once you address the non compiling in patch 1/3 (I'm >> getting blocked the unused var because somehow Werror is on, odd it >> didn't trip you up) but I also suspect this will have sparse go a bit >> nuts. >> I wonder if there is a nice way of shutting sparse up. >> >>> struct update_props_workarea *upwa; >>> struct device_node *dn; >>> @@ -136,6 +136,7 @@ static int update_dt_node(u32 phandle, s32 scope) >>> char *prop_data; >>> char *rtas_buf; >>> int update_properties_token; >>> + u32 nprops; >>> u32 vd; >>> >>> update_properties_token = rtas_token("ibm,update-properties"); >>> @@ -162,6 +163,7 @@ static int update_dt_node(u32 phandle, s32 scope) >>> break; >>> >>> prop_data = rtas_buf + sizeof(*upwa); >>> + nprops = be32_to_cpu(upwa->nprops); >>> >>> /* On the first call to ibm,update-properties for a node the >>> * the first property value descriptor contains an empty >>> @@ -170,17 +172,17 @@ static int update_dt_node(u32 phandle, s32 scope) >>> */ >>> if (*prop_data == 0) { >>> prop_data++; >>> - vd = *(u32 *)prop_data; >>> + vd = be32_to_cpu(*(__be32 *)prop_data); >>> prop_data += vd + sizeof(vd); >>> - upwa->nprops--; >>> + nprops--; >>> } >>> >>> - for (i = 0; i < upwa->nprops; i++) { >>> + for (i = 0; i < nprops; i++) { >>> char *prop_name; >>> >>> prop_name = prop_data; >>> prop_data += strlen(prop_name) + 1; >>> - vd = *(u32 *)prop_data; >>> + vd = be32_to_cpu(*(__be32 *)prop_data); >>> prop_data += sizeof(vd); >>> >>> switch (vd) { >>> @@ -212,7 +214,7 @@ static int update_dt_node(u32 phandle, s32 scope) >>> return 0; >>> } >>> >>> -static int add_dt_node(u32 parent_phandle, u32 drc_index) >>> +static int add_dt_node(__be32 parent_phandle, __be32 drc_index) >>> { >>> struct device_node *dn; >>> struct device_node *parent_dn; >>> @@ -237,7 +239,7 @@ static int add_dt_node(u32 parent_phandle, u32 >>> drc_index) >>> int pseries_devicetree_update(s32 scope) >>> { >>> char *rtas_buf; >>> - u32 *data; >>> + __be32 *data; >>> int update_nodes_token; >>> int rc; >>> >>> @@ -254,17 +256,17 @@ int pseries_devicetree_update(s32 scope) >>> if (rc && rc != 1) >>> break; >>> >>> - data = (u32 *)rtas_buf + 4; >>> - while (*data & NODE_ACTION_MASK) { >>> + data = (__be32 *)rtas_buf + 4; >>> + while (be32_to_cpu(*data) & NODE_ACTION_MASK) { >>> int i; >>> - u32 action = *data & NODE_ACTION_MASK; >>> - int node_count = *data & NODE_COUNT_MASK; >>> + u32 action = be32_to_cpu(*data) & NODE_ACTION_MASK; >>> + u32 node_count = be32_to_cpu(*data) & NODE_COUNT_MASK; >>> >>> data++; >>> >>> for (i = 0; i < node_count; i++) { >>> - u32 phandle = *data++; >>> - u32 drc_index; >>> + __be32 phandle = *data++; >>> + __be32 drc_index; >>> >>> switch (action) { >>> case DELETE_DT_NODE: >> >> The patch looks good, no nonsense endian fixing. >> Worth noting that it leaves existing bugs in place, which is fine, I'll >> rebase my patches which address endian and bugs on top of these so as to >> address the bugs. >> >> > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev