Re: [Crash-utility] [PATCH] arm64: deduce the start address of kernel code, based on kernel version

Hi Pingfan, thanks for the patch. -----Original Message----- > After kernel commit e2a073dde921 ("arm64: omit [_text, _stext) from > permanent kernel mapping"), the range [_text, _stext] is reclaimed. But > the current crash code still assumes kernel starting from "_text". > > This change only affects the vmalloced area on arm64 and may result a > false in arm64_IS_VMALLOC_ADDR(). > > Since vmcore has no extra information about this trival change, it can > only be deduced from kernel version, which means ms->kimage_text can not > be correctly initialized until kernel_init() finishes. This is fine > since there is no access to vmalloced area at this early stage. > > Signed-off-by: Pingfan Liu <piliu(a)redhat.com&gt; > --- > arm64.c | 17 +++++++++++++++++ > defs.h | 1 + > kernel.c | 3 +++ > 3 files changed, 21 insertions(+) > > diff --git a/arm64.c b/arm64.c > index 4f2c2b5..4aa971c 100644 > --- a/arm64.c > +++ b/arm64.c > @@ -92,6 +92,21 @@ static void arm64_calc_VA_BITS(void); > static int arm64_is_uvaddr(ulong, struct task_context *); > static void arm64_calc_KERNELPACMASK(void); > > +/* called by kernel_init() */ > +static void arm64_post_kernel_init(void) > +{ > + struct machine_specific *ms = machdep->machspec; > + struct syment *sp; > + > + if (THIS_KERNEL_VERSION >= LINUX(5,11,0)) > + sp = kernel_symbol_search("_stext"); > + else > + sp = kernel_symbol_search("_text"); > + > + ms->kimage_text = (sp ? sp->value : 0); > + sp = kernel_symbol_search("_end"); > + ms->kimage_end = (sp ? sp->value : 0); > +} > > /* > * Do all necessary machine-specific setup here. This is called several times > @@ -104,6 +119,7 @@ arm64_init(int when) > char *string; > struct machine_specific *ms; > > + arch_post_kernel_init = arm64_post_kernel_init; Why is the arch_post_kernel_init needed, i.e. can't we put it in machdep_init(POST_GDB)?