On Fri, Feb 25, 2022 at 1:01 AM <crash-utility-request@xxxxxxxxxx> wrote:
Date: Thu, 24 Feb 2022 11:52:12 +0800
From: Pingfan Liu <piliu@xxxxxxxxxx>
To: crash-utility@xxxxxxxxxx
Subject: [PATCHv2] arm64: deduce the start address of
kernel code, based on kernel version
Message-ID: <20220224035212.14186-1-piliu@xxxxxxxxxx>
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".
Thank you for the fix, Pingfan. Good findings.
The v2 looks good and the test is ok. Applied.
Lianbo
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@xxxxxxxxxx>
---
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
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