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.
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
So even more aggressive, we can exclude the need of vabits_actual
totally in this patch.
Thanks,
Pingfan
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