On 1/15/21 8:40 AM, HAGIO KAZUHITO(萩尾 一仁) wrote:
Hi Pingfan, Bhupesh,
Thank you for your comments!
-----Original Message-----
Hi Kazu,
On Thu, Jan 14, 2021 at 3:33 PM piliu <piliu@xxxxxxxxxx> wrote:
On 1/14/21 4:25 PM, kazuhito.hagio@xxxxxxxxx wrote:
From: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
Based on Bhupesh's patch and contains Pingfan's idea.
Signed-off-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx>
Signed-off-by: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
---
arch/arm64.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++----------
makedumpfile.c | 2 ++
makedumpfile.h | 1 +
3 files changed, 83 insertions(+), 15 deletions(-)
diff --git a/arch/arm64.c b/arch/arm64.c
index 61ec89a..4ece19d 100644
--- a/arch/arm64.c
+++ b/arch/arm64.c
@@ -47,6 +47,8 @@ typedef struct {
static int lpa_52_bit_support_available;
static int pgtable_level;
static int va_bits;
+static int vabits_actual;
+static int flipped_va;
static unsigned long kimage_voffset;
#define SZ_4K 4096
@@ -58,7 +60,6 @@ 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_52 ((0xffffffffffffffffUL) << 52)
#define pgd_val(x) ((x).pgd)
#define pud_val(x) (pgd_val((x).pgd))
@@ -218,12 +219,20 @@ pmd_page_paddr(pmd_t pmd)
#define pte_index(vaddr) (((vaddr) >> PAGESHIFT()) & (PTRS_PER_PTE - 1))
#define pte_offset(dir, vaddr) (pmd_page_paddr((*dir)) + pte_index(vaddr) *
sizeof(pte_t))
+/*
+ * The linear kernel range starts at the bottom of the virtual address
+ * space. Testing the top bit for the start of the region is a
+ * sufficient check and avoids having to worry about the tag.
+ */
+#define is_linear_addr(addr) (flipped_va ? \
+ (!((unsigned long)(addr) & (1UL << (vabits_actual - 1)))) : \
+ (!!((unsigned long)(addr) & (1UL << (vabits_actual - 1)))))
+
static unsigned long long
__pa(unsigned long vaddr)
{
- if (kimage_voffset == NOT_FOUND_NUMBER ||
- (vaddr >= PAGE_OFFSET))
- return (vaddr - PAGE_OFFSET + info->phys_base);
+ if (kimage_voffset == NOT_FOUND_NUMBER || is_linear_addr(vaddr))
+ return ((vaddr & ~PAGE_OFFSET) + info->phys_base);
else
return (vaddr - kimage_voffset);
}
@@ -253,6 +262,7 @@ static int calculate_plat_config(void)
(PAGESIZE() == SZ_64K && va_bits == 42)) {
pgtable_level = 2;
} else if ((PAGESIZE() == SZ_64K && va_bits == 48) ||
+ (PAGESIZE() == SZ_64K && va_bits == 52) ||
(PAGESIZE() == SZ_4K && va_bits == 39) ||
(PAGESIZE() == SZ_16K && va_bits == 47)) {
pgtable_level = 3;
@@ -263,6 +273,7 @@ static int calculate_plat_config(void)
PAGESIZE(), va_bits);
return FALSE;
}
+ DEBUG_MSG("pgtable_level: %d\n", pgtable_level);
return TRUE;
}
@@ -383,22 +394,54 @@ get_va_bits_from_stext_arm64(void)
return TRUE;
}
+static void
+get_page_offset_arm64(void)
+{
+ ulong page_end;
+ int vabits_min;
+
+ /*
+ * See arch/arm64/include/asm/memory.h for more details of
+ * the PAGE_OFFSET calculation.
+ */
+ vabits_min = (va_bits > 48) ? 48 : va_bits;
+ page_end = -(1UL << (vabits_min - 1));
+
+ if (SYMBOL(_stext) > page_end) {
+ flipped_va = TRUE;
+ info->page_offset = -(1UL << vabits_actual);
+ } else {
+ flipped_va = FALSE;
+ info->page_offset = -(1UL << (vabits_actual - 1));
+ }
+
+ DEBUG_MSG("page_offset : %lx (from page_end check)\n",
+ info->page_offset);
+}
+
int
get_machdep_info_arm64(void)
{
+ /* Check if va_bits is still not initialized. If still 0, call
+ * get_versiondep_info() to initialize the same.
+ */
+ if (!va_bits)
+ get_versiondep_info_arm64();
+
/* Determine if the PA address range is 52-bits: ARMv8.2-LPA */
if (NUMBER(MAX_PHYSMEM_BITS) != NOT_FOUND_NUMBER) {
info->max_physmem_bits = NUMBER(MAX_PHYSMEM_BITS);
+ DEBUG_MSG("max_physmem_bits : %ld (vmcoreinfo)\n", info->max_physmem_bits);
if (info->max_physmem_bits == 52)
lpa_52_bit_support_available = 1;
- } else
- info->max_physmem_bits = 48;
+ } else {
+ if (va_bits == 52)
+ info->max_physmem_bits = 52; /* just guess */
+ else
+ info->max_physmem_bits = 48;
- /* Check if va_bits is still not initialized. If still 0, call
- * get_versiondep_info() to initialize the same.
- */
- if (!va_bits)
- get_versiondep_info_arm64();
+ DEBUG_MSG("max_physmem_bits : %ld (guess)\n", info->max_physmem_bits);
+ }
if (!calculate_plat_config()) {
ERRMSG("Can't determine platform config values\n");
@@ -409,7 +452,6 @@ get_machdep_info_arm64(void)
info->section_size_bits = SECTIONS_SIZE_BITS;
DEBUG_MSG("kimage_voffset : %lx\n", kimage_voffset);
- DEBUG_MSG("max_physmem_bits : %ld\n", info->max_physmem_bits);
DEBUG_MSG("section_size_bits: %ld\n", info->section_size_bits);
return TRUE;
@@ -444,10 +486,33 @@ get_versiondep_info_arm64(void)
return FALSE;
}
- info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
+ /*
+ * See TCR_EL1, Translation Control Register (EL1) register
+ * description in the ARMv8 Architecture Reference Manual.
+ * Basically, we can use the TCR_EL1.T1SZ
+ * value to determine the virtual addressing range supported
+ * in the kernel-space (i.e. vabits_actual) since Linux 5.9.
+ */
+ if (NUMBER(TCR_EL1_T1SZ) != NOT_FOUND_NUMBER) {
+ vabits_actual = 64 - NUMBER(TCR_EL1_T1SZ);
+ DEBUG_MSG("vabits_actual : %d (vmcoreinfo)\n", vabits_actual);
+ } else if ((va_bits == 52) && (SYMBOL(mem_section) != NOT_FOUND_SYMBOL)) {
+ /*
+ * Linux 5.4 through 5.10 have the following linear space:
+ * 48-bit: 0xffff000000000000 - 0xffff7fffffffffff
+ * 58-bit: 0xfff0000000000000 - 0xfff7ffffffffffff
+ */
+ if (SYMBOL(mem_section) & (1UL << (52 - 1)))
Sorry but I do not think any SYMBOL(x) is inside the range of linear
mapping address. All of them should be beyond kimage_vaddr.
As for this, SYMBOL(mem_section) is a bit special and shows the value in the
mem_section variable, not the address of it, by kernel commit a0b1280368d1.
Actually on my tiny arm64 board..
# strings /proc/kcore | less
...
OSRELEASE=5.4.0-1025-raspi
PAGESIZE=4096
SYMBOL(init_uts_ns)=ffffd6db0fa10568
SYMBOL(node_online_map)=ffffd6db0fa0a808
SYMBOL(swapper_pg_dir)=ffffd6db0f42b000
SYMBOL(_stext)=ffffd6db0e481000
SYMBOL(vmap_area_list)=ffffd6db0fa51680
SYMBOL(mem_map)=ffffd6db0fbc0240
SYMBOL(contig_page_data)=ffffd6db0faed6c0
SYMBOL(mem_section)=ffff0000eb809300 <<--
LENGTH(mem_section)=1024
SIZE(mem_section)=16
OFFSET(mem_section.section_mem_map)=0
...
NUMBER(VA_BITS)=48
So at least if the kernel is configured with CONFIG_SPARSEMEM_EXTREME,
You are right. Exactly, your method works in this case.
I thought this would work. This is just a user tool effort to broaden
supported kernels, instead of necessary information from the kernel,
no need to support all kernels.
I hold a private opinion against the solution based on kernel version,
since it raises extra effort to cope with different releases which back
port some upstream patches without advancing kernel version.
And the current makedumpfile's implementation, SYMBOL(mem_section) is set
to the address of the mem_section variable with -x option, so I wrote on
the cover letter that this patchset doesn't support "with -x option if
vabits_actual=52" case yet.
Having vabits_actual is introduced and precise to resolve
is_lm_address(), but if it is not available, could we survive?
_PAGE_OFFSET(52) < _PAGE_END(52) < _PAGE_OFFSET(48) < _PAGE_END(48)
Translating into numbers:
0xfff0000000000000 < 0xfff8000000000000 < 0xffff000000000000 <
0xffff800000000000
Refer to linux/Documentation/arm64/memory.rst, the line
ffffa00010000000 fffff81ffffeffff ~88TB vmalloc
It comes to the conclusion that any symbol > SYMBOL(_text) > _PAGE_END(48).
So is_lm_address() can looks like
if (addr > _PAGE_END(48)), it is kimage
else, it is linear mapping
This sounds good and will work.
So even more aggressive, we can exclude the need of vabits_actual
totally in this patch.
Interesting, but if vabits_actual is not available, I wonder how we can
get info->page_offset. Seems it's used mainly for p2v conversion and
Ashamed. I will make the best of the fact that va_bits=52 kernel only
has _PAGE_OFFSET(52). It looks not elegant, but should work.
Regards,
Pingfan
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