Hi Song,
On 24/07/2023 06:06, Song Shuai wrote:
Since RISC-V Linux v6.4, the commit 3335068f8721 ("riscv: Use
PUD/P4D/PGD pages for the linear mapping") changes the
phys_ram_base from the kernel_map.phys_addr to the start of DRAM.
Maybe we could be more explicit here, kernel_map.phys_addr actually
points to the physical start of the kernel so maybe something like that:
"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 Crash can
use "va_kernel_pa_offset" to translate the kernel virtual address in
VTOP() correctly.
Signed-off-by: Song Shuai <suagrfillet@xxxxxxxxx>
---
You can check/test the Linux changes from this link:
https://github.com/sugarfillet/linux/commits/6.5-rc3-crash
And I'll send the Linux changes to riscv/for-next If you're ok with this patch.
---
defs.h | 4 ++--
riscv64.c | 22 ++++++++++++++++++++++
2 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/defs.h b/defs.h
index 358f365..46b9857 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..b9e50b4 100644
--- a/riscv64.c
+++ b/riscv64.c
@@ -418,6 +418,27 @@ 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();
+
+ /*
+ * va_kernel_pa_offset is defined in Linux kernel since 6.5.
+ */
+ if (kernel_version >= LINUX(6,5,0)) {
+ 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 if (kernel_version >= LINUX(6,4,0))
+ error(FATAL, "cannot determine va_kernel_pa_offset since Linux 6.4\n");
+ else
+ ms->va_kernel_pa_offset = ms->kernel_link_addr - ms->phys_base;
+}
+
static int
riscv64_is_kvaddr(ulong vaddr)
{
@@ -1352,6 +1373,7 @@ 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.");
Would you mind giving me the instructions on how to reproduce the issue
please? So that I can add that to our internal CI and avoid this type of
breakage in the future.
Thanks,
Alex
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