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From e3bdc32aab5d8fe09b679cf394da8ba8826e207f Mon Sep 17 00:00:00 2001
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From: Pingfan Liu <piliu@redhat.com>
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Date: Thu, 24 Feb 2022 11:52:12 +0800
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Subject: [PATCH] arm64: deduce the start address of kernel code, based on
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kernel version
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After kernel commit e2a073dde921 ("arm64: omit [_text, _stext) from
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permanent kernel mapping"), the range [_text, _stext] is reclaimed. But
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the current crash code still assumes kernel starting from "_text".
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This change only affects the vmalloced area on arm64 and may result a
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false in arm64_IS_VMALLOC_ADDR().
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Since vmcore has no extra information about this trival change, it can
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only be deduced from kernel version, which means ms->kimage_text can not
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be correctly initialized until kernel_init() finishes. Here on arm64, it
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can be done at the point machdep_init(POST_GDB). This is fine
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since there is no access to vmalloced area at this stage.
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Signed-off-by: Pingfan Liu <piliu@redhat.com>
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---
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arm64.c | 17 +++++++++++++++++
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1 file changed, 17 insertions(+)
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diff --git a/arm64.c b/arm64.c
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index de1038a..3ab8489 100644
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--- a/arm64.c
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+++ b/arm64.c
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@@ -92,6 +92,20 @@ static void arm64_calc_VA_BITS(void);
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static int arm64_is_uvaddr(ulong, struct task_context *);
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static void arm64_calc_KERNELPACMASK(void);
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+static void arm64_calc_kernel_start(void)
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+{
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+ struct machine_specific *ms = machdep->machspec;
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+ struct syment *sp;
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+
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+ if (THIS_KERNEL_VERSION >= LINUX(5,11,0))
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+ sp = kernel_symbol_search("_stext");
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+ else
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+ sp = kernel_symbol_search("_text");
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+
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+ ms->kimage_text = (sp ? sp->value : 0);
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+ sp = kernel_symbol_search("_end");
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+ ms->kimage_end = (sp ? sp->value : 0);
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+}
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/*
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* Do all necessary machine-specific setup here. This is called several times
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@@ -241,6 +255,7 @@ arm64_init(int when)
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if (machdep->flags & NEW_VMEMMAP) {
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struct syment *sp;
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+ /* It is finally decided in arm64_calc_kernel_start() */
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sp = kernel_symbol_search("_text");
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ms->kimage_text = (sp ? sp->value : 0);
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sp = kernel_symbol_search("_end");
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@@ -387,6 +402,8 @@ arm64_init(int when)
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break;
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case POST_GDB:
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+ /* Rely on kernel version to decide the kernel start address */
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+ arm64_calc_kernel_start();
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arm64_calc_virtual_memory_ranges();
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arm64_get_section_size_bits();
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--
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2.31.1
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