Commit 94c97db3fe859ca14d7b38b0ae9ee0ffb83689d2 (arm64: Get
'info->page_offset' from PT_LOAD segments to support KASLR boot cases)
added a method to determine 'info->page_offset' from PT_LOAD segments
for arm64 platforms.
In this commit we hardcoded the NOT_PADDR_ARM64 macro as
0x0000000010a80000UL which was a valid value on qualcomm-amberwing
boards.
However, I was testing this change on several other arm64 boards
like apm-mustang, huawei-taishan and hp-moonshot and saw that
this value can vary on the basic of the "Kernel code" memory
range placement.
To fix the same, this patchset uses a new approach. Since kernel
version 4.19-rc5 (Commit
23c85094fe1895caefdd19ef624ee687ec5f4507 ["proc/kcore: add vmcoreinfo
note to /proc/kcore"]), '/proc/kcore' contains a new
PT_NOTE which carries the VMCOREINFO information.
If the same is available, we can use it for makedumpfile
'show_mem_usage()' and other functionality. This is especially useful
for architectures like arm64 as we can get kernel symbols like
'VA_BITS' and 'kimage_voffset' from the '/proc/kcore' itself and use it
to calculate 'info->page_offset' when we make a call to
'get_page_offset()'.
This VMCOREINFO note provides us a standard interface which can be
leveraged while debugging live (or primary) kernel with makedumpfile
(and other user-space tools), especially to derive the machine specific
details (for e.g. VA_BITS, PHYS_OFFSET and kimage_voffset for arm64
arch).
I also verified the makedumpfile functionality in crash kernel with this
patchset. Here are some details of the tests I ran:
Testing:
--------
1. Architectures tested:
a) arm64 :- huawei-taishan, apm-mustang and qualcomm-amberwing boards.
b) x86_64 :- Dell optiplex workstation.
(NOTE that x86_64 makedumpfile --mem-usage use-case is currently
broken with upstream kernel, but I have debugged the root-cause
and will separately send a patch to fix the same).
2. Use-cases tested:
a) Primary kernel ->
[] --mem-usage:
# makedumpfile -f --mem-usage /proc/kcore
[] filtering use-case:
# makedumpfile --split -d 31 -x vmlinux --config scrub.conf vmcore dumpfile_{1,2,3}
[] dumpfile creation:
# makedumpfile -d 31 -x vmlinux vmcore dumpfile
b) Crash kernel ->
[] dumpfile creation:
# makedumpfile -l --message-level 31 -d 31 /proc/vmcore dump
3. Kernel versions tested:
a) Kernel version 4.19-rc5 and above on both arm64 and x86_64.
b) Fedora 28 on x86_64.
c) Kernel version 4.14 on arm64.
Fixes: 94c97db3fe859ca14d7b38b0ae9ee0ffb83689d2 "arm64: Get 'info->page_offset' from PT_LOAD segments to support KASLR boot cases"
Cc: Kazuhito Hagio <k-hagio@xxxxxxxxxxxxx>
Signed-off-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx>
---
arch/arm64.c | 114 +++++++++++++++++++++++++++++++++++++++++++--------------
makedumpfile.c | 67 ++++++++++++++++++++++++++++++---
makedumpfile.h | 2 +-
3 files changed, 149 insertions(+), 34 deletions(-)
diff --git a/arch/arm64.c b/arch/arm64.c
index 362609668ea2..d695eff628f0 100644
--- a/arch/arm64.c
+++ b/arch/arm64.c
@@ -53,6 +53,7 @@ static unsigned long kimage_voffset;
#define PAGE_OFFSET_42 ((0xffffffffffffffffUL) << 42)
#define PAGE_OFFSET_47 ((0xffffffffffffffffUL) << 47)
#define PAGE_OFFSET_48 ((0xffffffffffffffffUL) << 48)
+#define __PAGE_OFFSET(x) ((0xffffffffffffffffUL) << (x - 1))
#define pgd_val(x) ((x).pgd)
#define pud_val(x) (pgd_val((x).pgd))
@@ -311,45 +312,104 @@ get_versiondep_info_arm64(void)
unsigned long long virt_start;
ulong _stext;
- _stext = get_stext_symbol();
- if (!_stext) {
- ERRMSG("Can't get the symbol of _stext.\n");
- return FALSE;
- }
+ /* Calculate 'VA_BITS'. */
- /* Derive va_bits as per arch/arm64/Kconfig */
- if ((_stext & PAGE_OFFSET_36) == PAGE_OFFSET_36) {
- va_bits = 36;
- } else if ((_stext & PAGE_OFFSET_39) == PAGE_OFFSET_39) {
- va_bits = 39;
- } else if ((_stext & PAGE_OFFSET_42) == PAGE_OFFSET_42) {
- va_bits = 42;
- } else if ((_stext & PAGE_OFFSET_47) == PAGE_OFFSET_47) {
- va_bits = 47;
- } else if ((_stext & PAGE_OFFSET_48) == PAGE_OFFSET_48) {
- va_bits = 48;
+ /* Since kernel version 4.19, '/proc/kcore' contains a new
+ * PT_NOTE which carries the VMCOREINFO information.
+ *
+ * If the same is available, use it as it already contains the
+ * value of 'VA_BITS' on the machine.
+ *
+ * Otherwise, we can read the '_stext' symbol and determine the
+ * 'VA_BITS' value from the same as well.
+ */
+ if (info->flag_kcore_contains_vmcoreinfo &&
+ (NUMBER(VA_BITS) != NOT_FOUND_NUMBER)) {
+ va_bits = NUMBER(VA_BITS);
} else {
- ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n");
- return FALSE;
+ _stext = get_stext_symbol();
+ if (!_stext) {
+ ERRMSG("Can't get the symbol of _stext.\n");
+ return FALSE;
+ }
+
+ /* Derive va_bits as per arch/arm64/Kconfig */
+ if ((_stext & PAGE_OFFSET_36) == PAGE_OFFSET_36) {
+ va_bits = 36;
+ } else if ((_stext & PAGE_OFFSET_39) == PAGE_OFFSET_39) {
+ va_bits = 39;
+ } else if ((_stext & PAGE_OFFSET_42) == PAGE_OFFSET_42) {
+ va_bits = 42;
+ } else if ((_stext & PAGE_OFFSET_47) == PAGE_OFFSET_47) {
+ va_bits = 47;
+ } else if ((_stext & PAGE_OFFSET_48) == PAGE_OFFSET_48) {
+ va_bits = 48;
+ } else {
+ ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n");
+ return FALSE;
+ }
+ }
+
+ /* Calculate 'info->page_offset'. */
+
+ /* Since kernel version 4.19, '/proc/kcore' contains a new
+ * PT_NOTE which carries the VMCOREINFO information.
+ *
+ * If the same is available, use it as it already contains the
+ * value of 'kimage_voffset' on the machine.
+ */
+ if (info->flag_kcore_contains_vmcoreinfo &&
+ (NUMBER(kimage_voffset) != NOT_FOUND_NUMBER)) {
+ kimage_voffset = NUMBER(kimage_voffset);
}
+ /* First, lets try and calculate the 'info->page_offset' value
+ * from PT_LOAD segments, if they are available.
+ */
if (get_num_pt_loads()) {
for (i = 0;
get_pt_load(i, &phys_start, NULL, &virt_start, NULL);
i++) {
- if (virt_start != NOT_KV_ADDR
- && virt_start < __START_KERNEL_map
- && phys_start != NOT_PADDR
- && phys_start != NOT_PADDR_ARM64) {
- info->page_offset = virt_start - phys_start;
- DEBUG_MSG("info->page_offset: %lx, VA_BITS: %d\n",
- info->page_offset, va_bits);
- return TRUE;
+ /* On systems where we have a valid 'kimage_voffset'
+ * available by now, we should give preference to the same
+ * while calculating 'info->page_offset'.
+ *
+ * Otherwise, we can ensure that we consider
+ * only those PT_LOAD segments whose 'virt_start'
+ * is greater than the PAGE_OFFSET value (as defined
+ * in 'arch/arm64/include/asm/memory.h').
+ */
+ if (!kimage_voffset) {
+ if (virt_start != NOT_KV_ADDR &&
+ virt_start > __PAGE_OFFSET(va_bits) &&
+ phys_start != NOT_PADDR) {
+ info->page_offset = virt_start - phys_start;
+ DEBUG_MSG("info->page_offset: %lx, VA_BITS: %d\n",
+ info->page_offset, va_bits);
+ return TRUE;
+ }
+ } else {
+ if (virt_start != NOT_KV_ADDR &&
+ phys_start != NOT_PADDR &&
+ (virt_start - phys_start) != kimage_voffset) {
+ info->page_offset = virt_start - phys_start;
+ DEBUG_MSG("info->page_offset: %lx, VA_BITS: %d\n",
+ info->page_offset, va_bits);
+ return TRUE;
+ }
}
}
}
- info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
+ /* Fallback to hard-coded value (equal to PAGE_OFFSET macro
+ * defined in 'arch/arm64/include/asm/memory.h'), as the last
+ * resort.
+ *
+ * Note that this will not be a valid value on KASLR enabled
+ * kernels as the start address of linear range is also
+ * randomized for KASLR boot cases.
+ */
+ info->page_offset = __PAGE_OFFSET(va_bits);
DEBUG_MSG("page_offset=%lx, va_bits=%d\n", info->page_offset,
va_bits);
diff --git a/makedumpfile.c b/makedumpfile.c
index 3ccdaaeda0c5..59967f95e0d3 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -1302,6 +1302,20 @@ error:
return FALSE;
}
+static int
+check_kcore_contains_vmcoreinfo(int fd, char *name)
+{
+ if (!get_elf_info(fd, name))
+ return FALSE;
+
+ if (!has_vmcoreinfo())
+ return FALSE;
+
+ DEBUG_MSG("VMCOREINFO PT_NOTE found in %s\n", name);
+
+ return TRUE;
+}
+
int
open_dump_memory(void)
{
@@ -1314,6 +1328,23 @@ open_dump_memory(void)
}
info->fd_memory = fd;
+ /* Since kernel version 4.19, '/proc/kcore' contains a new
+ * PT_NOTE which carries the VMCOREINFO information.
+ *
+ * If the same is available, use it for makedumpfile
+ * show_mem_usage() cases.
+ */
+ if (info->flag_mem_usage &&
+ !(strcmp(info->name_memory, "/proc/kcore")) &&
+ (info->kernel_version >= KERNEL_VERSION(4, 19, 0))){
+ status = check_kcore_contains_vmcoreinfo(fd,
+ info->name_memory);
+ if (status == TRUE) {
+ info->flag_kcore_contains_vmcoreinfo = TRUE;
+ return TRUE;
+ }
+ }
+
status = check_kdump_compressed(info->name_memory);
if (status == TRUE) {
info->flag_refiltering = TRUE;
@@ -11195,6 +11226,8 @@ static int get_sys_kernel_vmcoreinfo(uint64_t *addr, uint64_t *len)
int show_mem_usage(void)
{
+ off_t offset;
+ unsigned long size;
uint64_t vmcoreinfo_addr, vmcoreinfo_len;
struct cycle cycle = {0};
@@ -11208,17 +11241,39 @@ int show_mem_usage(void)
if (!open_files_for_creating_dumpfile())
return FALSE;
- if (!get_elf_loads(info->fd_memory, info->name_memory))
- return FALSE;
+ /* Since kernel version 4.19, '/proc/kcore' contains a new
+ * PT_NOTE which carries the VMCOREINFO information.
+ *
+ * If the same is available, use it for makedumpfile
+ * show_mem_usage(). This is especially useful for architectures
+ * like arm64 as we can get symbols like 'VA_BITS' and
+ * 'kimage_voffset' before we call get_page_offset().
+ */
+
+ if (!info->flag_kcore_contains_vmcoreinfo) {
+ if (!get_elf_loads(info->fd_memory, info->name_memory))
+ return FALSE;
+ } else {
+ if (has_vmcoreinfo()) {
+ get_vmcoreinfo(&offset, &size);
+ if (!read_vmcoreinfo_from_vmcore(offset, size, FALSE))
+ return FALSE;
+ }
+ }
if (!get_page_offset())
return FALSE;
- if (!get_sys_kernel_vmcoreinfo(&vmcoreinfo_addr, &vmcoreinfo_len))
- return FALSE;
+ /* If flag_kcore_contains_vmcoreinfo is TRUE when we are here,
+ * we don't need to read the vmcoreinfo again.
+ */
+ if (!info->flag_kcore_contains_vmcoreinfo)
+ if (!get_sys_kernel_vmcoreinfo(&vmcoreinfo_addr, &vmcoreinfo_len))
+ return FALSE;
- if (!set_kcore_vmcoreinfo(vmcoreinfo_addr, vmcoreinfo_len))
- return FALSE;
+ if (!info->flag_kcore_contains_vmcoreinfo)
+ if (!set_kcore_vmcoreinfo(vmcoreinfo_addr, vmcoreinfo_len))
+ return FALSE;
if (!initial())
return FALSE;
diff --git a/makedumpfile.h b/makedumpfile.h
index d1fcd87e85f5..3ae683774fe5 100644
--- a/makedumpfile.h
+++ b/makedumpfile.h
@@ -544,7 +544,6 @@ unsigned long get_kvbase_arm64(void);
#define KVBASE get_kvbase_arm64()
#define __START_KERNEL_map (0xffffffff80000000UL)
-#define NOT_PADDR_ARM64 (0x0000000010a80000UL)
#endif /* aarch64 */
@@ -1307,6 +1306,7 @@ struct DumpInfo {
int flag_vmemmap; /* kernel supports vmemmap address space */
int flag_excludevm; /* -e - excluding unused vmemmap pages */
int flag_use_count; /* _refcount is named _count in struct page */
+ int flag_kcore_contains_vmcoreinfo; /* '/proc/kcore' contains a VMCOREINFO PT_NOTE */
unsigned long vaddr_for_vtop; /* virtual address for debugging */
long page_size; /* size of page */
long page_shift;
--
2.7.4
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