On 16/10/2013 09:28, Simon Horman wrote: > On Tue, Oct 15, 2013 at 07:05:28PM +0200, Laurent Dufour wrote: >> While reviewing fs2dt.c in the common kexec directory, in order to use it to >> support little endian ppc64 architecture, I found some endianess >> conversion's issues. >> >> In dt_reserve, dt_base is a pointer and thus should not be converted. >> >> In checkprop, values read from the device tree are big endian encoded and >> should be converted if CPU is running in little endian mode. >> >> In add_dyn_reconf_usable_mem_property__, fix extraneous endianess conversion >> of rlen which should be natively used to increase the dt pointer. > > These changes seem logical to me. > > However, I'm unsure how the code might have worked as-is. > In particular I'm pretty sure ARM was running in little endian > mode when I worked on DT support for it. Perhaps these code > paths were not executed. Or the errors cancelled themselves out somehow? I've to admit that I don't know how this has worked for ARM. I run this patch with a set of change I'm working on to support PPC64 little endian architecture. My tests were done with kexec-tools built in little endian mode, using this fs2dt.c file and I need this fix to build a valid device tree. The fix is dt_reserve is hit unless the device tree is large enough. I had to reduce INIT_TREE_WORDS to hit it. I think the ones in checkprop, add_dyn_reconf_usable_mem_property__ are Power specific since RTAS and 'ibm,dynamic-memory' are required to hit them. This may explain why this issue are not seen in ARM mode. This being said, I wondering if the files fs2dt.c defined in the arch/ppc64 and arch/ppc directories need to be kept. What do you think about removing those files and belong on the common kexec/fs2dt.c file for all the supported architecture ? Cheers, Laurent. >> >> Signed-off-by: Laurent Dufour <ldufour at linux.vnet.ibm.com> >> --- >> kexec/fs2dt.c | 19 +++++++++++-------- >> 1 file changed, 11 insertions(+), 8 deletions(-) >> >> diff --git a/kexec/fs2dt.c b/kexec/fs2dt.c >> index 242a15e..5d774ae 100644 >> --- a/kexec/fs2dt.c >> +++ b/kexec/fs2dt.c >> @@ -84,7 +84,7 @@ static void dt_reserve(unsigned **dt_ptr, unsigned words) >> offset = *dt_ptr - dt_base; >> dt_base = new_dt; >> dt_cur_size = new_size; >> - *dt_ptr = cpu_to_be32((unsigned)dt_base + offset); >> + *dt_ptr = dt_base + offset; >> memset(*dt_ptr, 0, (new_size - offset)*4); >> } >> } >> @@ -112,19 +112,22 @@ static void checkprop(char *name, unsigned *data, int len) >> if ((data == NULL) && (base || size || end)) >> die("unrecoverable error: no property data"); >> else if (!strcmp(name, "linux,rtas-base")) >> - base = *data; >> + base = be32_to_cpu(*data); >> else if (!strcmp(name, "linux,tce-base")) >> - base = *(unsigned long long *) data; >> + base = be64_to_cpu(*(unsigned long long *) data); >> else if (!strcmp(name, "rtas-size") || >> !strcmp(name, "linux,tce-size")) >> - size = *data; >> + size = be32_to_cpu(*data); >> else if (reuse_initrd && !strcmp(name, "linux,initrd-start")) >> if (len == 8) >> - base = *(unsigned long long *) data; >> + base = be64_to_cpu(*(unsigned long long *) data); >> else >> - base = *data; >> + base = be32_to_cpu(*data); >> else if (reuse_initrd && !strcmp(name, "linux,initrd-end")) >> - end = *(unsigned long long *) data; >> + if (len == 8) >> + end = be64_to_cpu(*(unsigned long long *) data); >> + else >> + end = be32_to_cpu(*data); >> >> if (size && end) >> die("unrecoverable error: size and end set at same time\n"); >> @@ -267,7 +270,7 @@ static void add_dyn_reconf_usable_mem_property__(int fd) >> pad_structure_block(rlen); >> memcpy(dt, ranges, rlen); >> free(ranges); >> - dt += cpu_to_be32((rlen + 3)/4); >> + dt += (rlen + 3)/4; >> } >> >> static void add_dyn_reconf_usable_mem_property(struct dirent *dp, int fd) >> >