On 12/22/23 at 09:29pm, Baoquan He wrote: > On 12/22/23 at 08:18pm, fuqiang wang wrote: > > In memmap_exclude_ranges(), there will exclude elfheader from > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > elfheader will be excluded from crashk_res. OR > it will exclude elfheader from crashk_res. > > > crashk_res. In the current x86 architecture code, the elfheader is > > always allocated at crashk_res.start. It seems that there won't be a > > split a new range. But it depends on the allocation position of > ~~~~~~~~~~~~~~~~~~ > It seems that there won't be a new split range. > > elfheader in crashk_res. To avoid potential out of bounds in future, add > > a extra slot. > > > > The similar issue also exists in fill_up_crash_elf_data(). The range to > > be excluded is [0, 1M], start (0) is special and will not appear in the > > middle of existing cmem->ranges[]. But in order to lest the low 1M could > ~~~~~~~~~~~~~~~~ > in case > > be changed in the future, add a extra slot too. > > > > Previously discussed link: > > [1] https://lore.kernel.org/kexec/ZXk2oBf%2FT1Ul6o0c@MiWiFi-R3L-srv/ > > [2] https://lore.kernel.org/kexec/273284e8-7680-4f5f-8065-c5d780987e59@xxxxxxxxxxxx/ > > [3] https://lore.kernel.org/kexec/ZYQ6O%2F57sHAPxTHm@MiWiFi-R3L-srv/ > > > > Signed-off-by: fuqiang wang <fuqiang.wang@xxxxxxxxxxxx> > > --- > > arch/x86/kernel/crash.c | 21 +++++++++++++++++++-- > > 1 file changed, 19 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > > index c92d88680dbf..97d33a6fc4fb 100644 > > --- a/arch/x86/kernel/crash.c > > +++ b/arch/x86/kernel/crash.c > > @@ -149,8 +149,18 @@ static struct crash_mem *fill_up_crash_elf_data(void) > > /* > > * Exclusion of crash region and/or crashk_low_res may cause > > * another range split. So add extra two slots here. > > + * > > + * Exclusion of low 1M may not cause another range split, because the > > + * range of exclude is [0, 1M] and the condition for splitting a new > > + * region is that the start, end parameters are both in a certain > > + * existing region in cmem and cannot be equal to existing region's > > + * start or end. Obviously, the start of [0, 1M] cannot meet this > > + * condition. > > + * > > + * But in order to lest the low 1M could be changed in the future, > > + * (e.g. [stare, 1M]), add a extra slot. Rethink about this, seems above code comment is fine to be kept, and the same feeling about the elfheader region split from crashk_res. So, other than the patch log concerns, this patch looks good to me. Let's see if other people has concern about the newly added comments. > > Sometime, too much is as bad as too little. I feel below words are > enough to state three regions are gonna be excluded, and may cause > another split (may not cause). The code comment plus commit log can help > people know why they are needed. > > * Exclusion of low1M, crashk_res and/or crashk_low_res may cause > * another range split. So add extra three slots here. > > > */ > > - nr_ranges += 2; > > + nr_ranges += 3; > > cmem = vzalloc(struct_size(cmem, ranges, nr_ranges)); > > if (!cmem) > > return NULL; > > @@ -282,9 +292,16 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params) > > struct crash_memmap_data cmd; > > struct crash_mem *cmem; > > > > - cmem = vzalloc(struct_size(cmem, ranges, 1)); > > + /* > > + * In the current x86 architecture code, the elfheader is always > > + * allocated at crashk_res.start. But it depends on the allocation > > + * position of elfheader in crashk_res. To avoid potential out of > > + * bounds in future, add a extra slot. > > + */ > > Ditto. > > + /* > + * Elfheader gonna be excluded from crashk_res, to avoid potential > + * out of bounds, add one extra slot. > + */ > > > + cmem = vzalloc(struct_size(cmem, ranges, 2)); > > if (!cmem) > > return -ENOMEM; > > + cmem->max_nr_ranges = 2; > > > > memset(&cmd, 0, sizeof(struct crash_memmap_data)); > > cmd.params = params; > > -- > > 2.42.0 > > > _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
