[Crash-utility] [PATCHv4] crash-utility/arm64: store phy_offset and memstart_addr separately
Pingfan Liu
piliu at redhat.com
Tue Apr 27 02:42:59 UTC 2021
Crash encounters a bug like the following:
...
SECTION_SIZE_BITS: 30
CONFIG_ARM64_VA_BITS: 52
VA_BITS_ACTUAL: 48
(calculated) VA_BITS: 48
PAGE_OFFSET: ffff000000000000
VA_START: ffff800000000000
modules: ffff800008000000 - ffff80000fffffff
vmalloc: ffff800010000000 - ffffffdfdffeffff
kernel image: ffff800010000000 - ffff800012750000
vmemmap: ffffffdfffe00000 - ffffffffffffffff
<readmem: ffff800011c53bc8, KVADDR, "nr_irqs", 4, (FOE), b47bdc>
<read_kdump: addr: ffff800011c53bc8 paddr: eb453bc8 cnt: 4>
read_netdump: addr: ffff800011c53bc8 paddr: eb453bc8 cnt: 4 offset: 1c73bc8
irq_stack_ptr:
type: 1, TYPE_CODE_PTR
target_typecode: 8, TYPE_CODE_INT
target_length: 8
length: 8
GNU_GET_DATATYPE[thread_union]: returned via gdb_error_hook
<readmem: ffff000b779c0050, KVADDR, "IRQ stack pointer", 8, (ROE), 3a37bea0>
<read_kdump: addr: ffff000b779c0050 paddr: fff1000bf79c0050 cnt: 8>
read_netdump: READ_ERROR: offset not found for paddr: fff1000bf79c0050
crash: read error: kernel virtual address: ffff000b779c0050 type: "IRQ stack pointer"
<readmem: ffff000b77a60050, KVADDR, "IRQ stack pointer", 8, (ROE), 3a37bea8>
<read_kdump: addr: ffff000b77a60050 paddr: fff1000bf7a60050 cnt: 8>
read_netdump: READ_ERROR: offset not found for paddr: fff1000bf7a60050
...
Apparently, for a normal system, the 'paddr: fff1000bf79c0050' is
unreasonable.
This bug connects with kernel commit 7bc1a0f9e176 ("arm64: mm: use
single quantity to represent the PA to VA translation"), memstart_addr
can be negative, which makes it different from real phys_offset. If
using memstart_addr to calculate the real paddr, the unreasonable paddr
will be got.
Furthermore, in crash utility, PTOV() needs memstart_addr to calculate
VA from PA, while getting PFN offset in a dumpfile, phys_offset is
required.
To serve the different purpose, using phys_offset_nominal and
phys_offset to store them.
Signed-off-by: Pingfan Liu <piliu at redhat.com>
Cc: HAGIO KAZUHITO <k-hagio-ab at nec.com>
Cc: Lianbo Jiang <lijiang at redhat.com>
Cc: Bhupesh Sharma <bhupesh.sharma at linaro.org>
To: crash-utility at redhat.com
---
v3 -> v4:
use _PAGE_OFFSET(va) to define MEMSTART_ADDR_OFFSET
and use the formula "#define __lm_to_phys(addr) (((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)"
for arm64_VTOP()
v2 -> v3:
rename ms->memstart_addr as ms->phys_offset_nominal ( I keep the name
as phys_offset* since it is in accordance with other platform
conventions)
---
arm64.c | 45 ++++++++++++++++++++++++++++++++++++++++-----
defs.h | 3 +++
2 files changed, 43 insertions(+), 5 deletions(-)
diff --git a/arm64.c b/arm64.c
index 4787fa6..84addde 100644
--- a/arm64.c
+++ b/arm64.c
@@ -23,6 +23,10 @@
#include <sys/ioctl.h>
#define NOT_IMPLEMENTED(X) error((X), "%s: function not implemented\n", __func__)
+/*
+ * _PAGE_OFFSET() refers to arch/arm64/include/asm/memory.h
+ */
+#define _PAGE_OFFSET(va) (-1UL << (va))
static struct machine_specific arm64_machine_specific = { 0 };
static int arm64_verify_symbol(const char *, ulong, char);
@@ -687,6 +691,7 @@ arm64_dump_machdep_table(ulong arg)
fprintf(fp, " kimage_voffset: %016lx\n", ms->kimage_voffset);
}
fprintf(fp, " phys_offset: %lx\n", ms->phys_offset);
+ fprintf(fp, " phys_offset_nominal: %lx\n", ms->phys_offset_nominal);
fprintf(fp, "__exception_text_start: %lx\n", ms->__exception_text_start);
fprintf(fp, " __exception_text_end: %lx\n", ms->__exception_text_end);
fprintf(fp, " __irqentry_text_start: %lx\n", ms->__irqentry_text_start);
@@ -987,7 +992,12 @@ arm64_calc_physvirt_offset(void)
ulong physvirt_offset;
struct syment *sp;
- ms->physvirt_offset = ms->phys_offset - ms->page_offset;
+ /*
+ * source arch/arm64/include/asm/memory.h
+ * #define __lm_to_phys(addr) (((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
+ * the part "addr & ~PAGE_OFFSET" is done in arm64_VTOP()
+ */
+ ms->physvirt_offset = ms->phys_offset_nominal;
if ((sp = kernel_symbol_search("physvirt_offset")) &&
machdep->machspec->kimage_voffset) {
@@ -1002,6 +1012,8 @@ arm64_calc_physvirt_offset(void)
static void
arm64_calc_phys_offset(void)
{
+#define MEMSTART_ADDR_OFFSET _PAGE_OFFSET(48) - _PAGE_OFFSET(52)
+
struct machine_specific *ms = machdep->machspec;
ulong phys_offset;
@@ -1028,7 +1040,11 @@ arm64_calc_phys_offset(void)
ms->kimage_voffset && (sp = kernel_symbol_search("memstart_addr"))) {
if (pc->flags & PROC_KCORE) {
if ((string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)"))) {
- ms->phys_offset = htol(string, QUIET, NULL);
+ ms->phys_offset_nominal = htol(string, QUIET, NULL);
+ if (ms->phys_offset_nominal < 0)
+ ms->phys_offset = ms->phys_offset_nominal + MEMSTART_ADDR_OFFSET;
+ else
+ ms->phys_offset = ms->phys_offset_nominal;
free(string);
return;
}
@@ -1080,7 +1096,18 @@ arm64_calc_phys_offset(void)
} else if (DISKDUMP_DUMPFILE() && diskdump_phys_base(&phys_offset)) {
ms->phys_offset = phys_offset;
} else if (KDUMP_DUMPFILE() && arm64_kdump_phys_base(&phys_offset)) {
- ms->phys_offset = phys_offset;
+ /*
+ * When running a 52bits kernel on 48bits hardware. Kernel plays a trick:
+ * if (IS_ENABLED(CONFIG_ARM64_VA_BITS_52) && (vabits_actual != 52))
+ * memstart_addr -= _PAGE_OFFSET(48) - _PAGE_OFFSET(52);
+ *
+ * In crash, this should be detected to get a real physical start address.
+ */
+ ms->phys_offset_nominal = phys_offset;
+ if ((long)phys_offset < 0)
+ ms->phys_offset = phys_offset + MEMSTART_ADDR_OFFSET;
+ else
+ ms->phys_offset = phys_offset;
} else {
error(WARNING,
"phys_offset cannot be determined from the dumpfile.\n");
@@ -1180,8 +1207,16 @@ arm64_VTOP(ulong addr)
return addr - machdep->machspec->kimage_voffset;
}
- if (addr >= machdep->machspec->page_offset)
- return addr + machdep->machspec->physvirt_offset;
+ if (addr >= machdep->machspec->page_offset) {
+ ulong paddr;
+
+ /*
+ * #define __lm_to_phys(addr) (((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
+ */
+ paddr = addr & ~ _PAGE_OFFSET(machdep->machspec->CONFIG_ARM64_VA_BITS);
+ paddr += machdep->machspec->physvirt_offset;
+ return paddr;
+ }
else if (machdep->machspec->kimage_voffset)
return addr - machdep->machspec->kimage_voffset;
else /* no randomness */
diff --git a/defs.h b/defs.h
index f9c711c..0a152f1 100644
--- a/defs.h
+++ b/defs.h
@@ -3289,7 +3289,10 @@ struct machine_specific {
ulong vmemmap_end;
ulong modules_vaddr;
ulong modules_end;
+ /* real physical offset */
ulong phys_offset;
+ /* read from kernel symbol memstart_addr */
+ long phys_offset_nominal;
ulong __exception_text_start;
ulong __exception_text_end;
struct arm64_pt_regs *panic_task_regs;
--
2.29.2
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