Re: [Crash-utility] [PATCH] 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. 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;

#if defined(__x86_64__) if (ACTIVE()) error(FATAL, "compiled for the ARM64 architecture\n"); @@ -241,6 +257,7 @@ arm64_init(int when) if (machdep->flags & NEW_VMEMMAP) { struct syment *sp; + /* It is finally decided in arm64_post_kernel_init() */ sp = kernel_symbol_search("_text"); ms->kimage_text = (sp ? sp->value : 0); sp = kernel_symbol_search("_end"); diff --git a/defs.h b/defs.h index 7d386d2..04ab55a 100644 --- a/defs.h +++ b/defs.h @@ -5677,6 +5677,7 @@ struct command_table_entry *crash_cmd_table(void); /* * kernel.c */ +extern void (*arch_post_kernel_init)(void); void kernel_init(void); void module_init(void); void verify_version(void); diff --git a/kernel.c b/kernel.c index 9c4aabf..b64ffac 100644 --- a/kernel.c +++ b/kernel.c @@ -98,6 +98,7 @@ static char *vmcoreinfo_read_string(const char *); static void check_vmcoreinfo(void); static int is_pvops_xen(void); +void (*arch_post_kernel_init)(void); /* * Gather a few kernel basics. @@ -823,6 +824,8 @@ kernel_init() source_tree_init(); kt->flags &= ~PRE_KERNEL_INIT; + if (arch_post_kernel_init) + arch_post_kernel_init(); } /* -- 2.31.1 -- Crash-utility mailing list Crash-utility(a)redhat.com https://listman.redhat.com/mailman/listinfo/crash-utility