在 2023/8/14 16:27, lijiang 写道:
Thank you for the update, Song.
On Mon, Aug 14, 2023 at 9:54 AM <crash-utility-request@xxxxxxxxxx
<mailto:crash-utility-request@xxxxxxxxxx>> wrote:
Date: Fri, 4 Aug 2023 17:15:59 +0800
From: Song Shuai <suagrfillet@xxxxxxxxx <mailto:suagrfillet@xxxxxxxxx>>
To: xianting.tian@xxxxxxxxxxxxxxxxx
<mailto:xianting.tian@xxxxxxxxxxxxxxxxx>, mick@xxxxxxxxxxxx
<mailto:mick@xxxxxxxxxxxx>,
heinrich.schuchardt@xxxxxxxxxxxxx
<mailto:heinrich.schuchardt@xxxxxxxxxxxxx>, guoren@xxxxxxxxxx
<mailto:guoren@xxxxxxxxxx>,
k-hagio-ab@xxxxxxx <mailto:k-hagio-ab@xxxxxxx>, yixun.lan@xxxxxxxxx
<mailto:yixun.lan@xxxxxxxxx>, lijiang@xxxxxxxxxx
<mailto:lijiang@xxxxxxxxxx>
Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx
<mailto:linux-riscv@xxxxxxxxxxxxxxxxxxx>, kexec@xxxxxxxxxxxxxxxxxxx
<mailto:kexec@xxxxxxxxxxxxxxxxxxx>,
crash-utility@xxxxxxxxxx <mailto:crash-utility@xxxxxxxxxx>, Song
Shuai <suagrfillet@xxxxxxxxx <mailto:suagrfillet@xxxxxxxxx>>
Subject: [Crash-utility PATCH V2] RISCV64: Use
va_kernel_pa_offset in VTOP()
Message-ID: <20230804091559.3005820-1-suagrfillet@xxxxxxxxx
<mailto:20230804091559.3005820-1-suagrfillet@xxxxxxxxx>>
Content-Type: text/plain; charset="US-ASCII"; x-default=true
Since RISC-V Linux v6.4, the commit 3335068f8721 ("riscv: Use
PUD/P4D/PGD pages for the linear mapping") changes phys_ram_base from
the physical start of the kernel to the actual start of the DRAM.
The Crash's VTOP() still uses phys_ram_base and kernel_map.virt_addr
to translate kernel virtual address, that made Crash boot failed with
Linux v6.4 and later version.
Let Linux export kernel_map.va_kernel_pa_offset in v6.5 and backported
v6.4.0 stable, so Crash can use "va_kernel_pa_offset" to translate the
kernel virtual address in VTOP() correctly.
Signed-off-by: Song Shuai <suagrfillet@xxxxxxxxx
<mailto:suagrfillet@xxxxxxxxx>>
---
Changes since V1:
- remove unnecessary first kernel version check as Kazu suggested
- amend the commit-msg as Alex suggested
---
defs.h | 4 ++--
riscv64.c | 23 +++++++++++++++++++++++
2 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/defs.h b/defs.h
index 5ee60f1..c07e6d7 100644
--- a/defs.h
+++ b/defs.h
@@ -3662,8 +3662,7 @@ typedef signed int s32;
ulong _X = X;
\
(THIS_KERNEL_VERSION >= LINUX(5,13,0) &&
\
(_X) >= machdep->machspec->kernel_link_addr) ?
\
- (((unsigned
long)(_X)-(machdep->machspec->kernel_link_addr)) + \
- machdep->machspec->phys_base):
\
+ ((unsigned
long)(_X)-(machdep->machspec->va_kernel_pa_offset)): \
(((unsigned long)(_X)-(machdep->kvbase)) +
\
machdep->machspec->phys_base);
\
})
@@ -7021,6 +7020,7 @@ struct machine_specific {
ulong modules_vaddr;
ulong modules_end;
ulong kernel_link_addr;
+ ulong va_kernel_pa_offset;
ulong _page_present;
ulong _page_read;
diff --git a/riscv64.c b/riscv64.c
index 6b9a688..7b5dd3d 100644
--- a/riscv64.c
+++ b/riscv64.c
@@ -418,6 +418,28 @@ error:
error(FATAL, "cannot get vm layout\n");
}
+static void
+riscv64_get_va_kernel_pa_offset(struct machine_specific *ms)
+{
+ unsigned long kernel_version = riscv64_get_kernel_version();
+
+ /*
+ * Since Linux v6.4 phys_base is not the physical start of
the kernel,
+ * trying to use "va_kernel_pa_offset" to determine the
offset between
+ * kernel virtual and physical addresses.
+ */
+ if (kernel_version >= LINUX(6,4,0)) {
Is it possible to detect the existence of the symbol
'linear_mapping_va_to_pa' or 'linear_mapping_pa_to_va' to decide reading
the value of 'va_kernel_pa_offset'? For example:
kernel_symbol_exists()/symbol_exists()
if (kernel_symbol_exists("linear_mapping_va_to_pa") ||
kernel_symbol_exists("linear_mapping_pa_to_va")) {
string = pc->read_vmcoreinfo("NUMBER(va_kernel_pa_offset)");
...
}
The `linear_mapping_va_to_pa` and `linear_mapping_pa_to_va` symbols will
only be exported when the debug option -- CONFIG_DEBUG_VIRTUAL is
enabled, otherwise they will expanded as macros. As the kernel Makefile
says:
obj-$(CONFIG_DEBUG_VIRTUAL) += physaddr.o
Actually, it's hard to extract some explicit infomation from the commit
3335068f8721 and use them as the first `if` condition, so the kernel
version checking was the final choice.
I saw the commit 3335068f8721 exported two symbols:
+phys_addr_t linear_mapping_va_to_pa(unsigned long x)
+{
+ BUG_ON(!kernel_map.va_pa_offset);
+
+ return ((unsigned long)(x) - kernel_map.va_pa_offset);
+}
+EXPORT_SYMBOL(linear_mapping_va_to_pa);
+
+void *linear_mapping_pa_to_va(unsigned long x)
+{
+ BUG_ON(!kernel_map.va_pa_offset);
+
+ return ((void *)((unsigned long)(x) + kernel_map.va_pa_offset));
+}
+EXPORT_SYMBOL(linear_mapping_pa_to_va);
Thanks.
Lianbo
+ char *string;
+ if ((string =
pc->read_vmcoreinfo("NUMBER(va_kernel_pa_offset)"))) {
+ ms->va_kernel_pa_offset = htol(string,
QUIET, NULL);
+ free(string);
+ } else
+ error(FATAL, "cannot read
va_kernel_pa_offset\n");
+ }
+ else
+ ms->va_kernel_pa_offset = ms->kernel_link_addr -
ms->phys_base;
+}
+
static int
riscv64_is_kvaddr(ulong vaddr)
{
@@ -1352,6 +1374,7 @@ riscv64_init(int when)
riscv64_get_struct_page_size(machdep->machspec);
riscv64_get_va_bits(machdep->machspec);
riscv64_get_va_range(machdep->machspec);
+ riscv64_get_va_kernel_pa_offset(machdep->machspec);
pt_level_alloc(&machdep->pgd, "cannot malloc pgd
space.");
pt_level_alloc(&machdep->machspec->p4d, "cannot
malloc p4d space.");
--
2.20.1
--
Thanks
Song Shuai
--
Crash-utility mailing list
Crash-utility@xxxxxxxxxx
https://listman.redhat.com/mailman/listinfo/crash-utility
Contribution Guidelines: https://github.com/crash-utility/crash/wiki
