Re: [Crash-utility] [PATCHv2] arm64: deduce the start address of kernel code, based on kernel version

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. Here on arm64, it can be done at the point machdep_init(POST_GDB). This is fine since there is no access to vmalloced area at this stage. Signed-off-by: Pingfan Liu <piliu(a)redhat.com&gt;

--- arm64.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/arm64.c b/arm64.c index de1038a..3ab8489 100644 --- a/arm64.c +++ b/arm64.c @@ -92,6 +92,20 @@ static void arm64_calc_VA_BITS(void); static int arm64_is_uvaddr(ulong, struct task_context *); static void arm64_calc_KERNELPACMASK(void); +static void arm64_calc_kernel_start(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 @@ -241,6 +255,7 @@ arm64_init(int when) if (machdep->flags & NEW_VMEMMAP) { struct syment *sp; + /* It is finally decided in arm64_calc_kernel_start() */ sp = kernel_symbol_search("_text"); ms->kimage_text = (sp ? sp->value : 0); sp = kernel_symbol_search("_end"); @@ -387,6 +402,8 @@ arm64_init(int when) break; case POST_GDB: + /* Rely on kernel version to decide the kernel start address */ + arm64_calc_kernel_start(); arm64_calc_virtual_memory_ranges(); arm64_get_section_size_bits(); -- 2.31.1