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First phase of support of the upcoming ARM64 kernel memory map
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changes to support 52-bit kernel virtual addressing, which allows
the configuration of CONFIG_ARM64_VA_BITS to be 52, but where the
actual number of VA bits may be downgraded during boot depending
upon the hardware capability.  This phase is only applicable for
live system analysis.
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Dave Anderson committed Mar 22, 2019
1 parent 302396b commit b0b3ef2
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Showing 2 changed files with 129 additions and 36 deletions.
153 changes: 118 additions & 35 deletions arm64.c
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Original file line number Diff line number Diff line change
Expand Up @@ -212,12 +212,19 @@ arm64_init(int when)

arm64_calc_VA_BITS();
ms = machdep->machspec;
ms->page_offset = ARM64_PAGE_OFFSET;
machdep->identity_map_base = ARM64_PAGE_OFFSET;
machdep->kvbase = ARM64_VA_START;
if (ms->VA_BITS_ACTUAL) {
ms->page_offset = ARM64_PAGE_OFFSET_ACTUAL;
machdep->identity_map_base = ARM64_PAGE_OFFSET_ACTUAL;
machdep->kvbase = ARM64_PAGE_OFFSET_ACTUAL;
ms->userspace_top = ARM64_USERSPACE_TOP_ACTUAL;
} else {
ms->page_offset = ARM64_PAGE_OFFSET;
machdep->identity_map_base = ARM64_PAGE_OFFSET;
machdep->kvbase = ARM64_VA_START;
ms->userspace_top = ARM64_USERSPACE_TOP;
}
machdep->is_kvaddr = generic_is_kvaddr;
machdep->kvtop = arm64_kvtop;
ms->userspace_top = ARM64_USERSPACE_TOP;
if (machdep->flags & NEW_VMEMMAP) {
struct syment *sp;

Expand All @@ -226,11 +233,15 @@ arm64_init(int when)
sp = kernel_symbol_search("_end");
ms->kimage_end = (sp ? sp->value : 0);

ms->modules_vaddr = ARM64_VA_START;
if (kernel_symbol_exists("kasan_init"))
ms->modules_vaddr += ARM64_KASAN_SHADOW_SIZE;
ms->modules_end = ms->modules_vaddr
+ ARM64_MODULES_VSIZE -1;
if (ms->VA_BITS_ACTUAL) {
ms->modules_vaddr = (st->_stext_vmlinux & TEXT_OFFSET_MASK) - ARM64_MODULES_VSIZE;
ms->modules_end = ms->modules_vaddr + ARM64_MODULES_VSIZE -1;
} else {
ms->modules_vaddr = ARM64_VA_START;
if (kernel_symbol_exists("kasan_init"))
ms->modules_vaddr += ARM64_KASAN_SHADOW_SIZE;
ms->modules_end = ms->modules_vaddr + ARM64_MODULES_VSIZE -1;
}

ms->vmalloc_start_addr = ms->modules_end + 1;

Expand Down Expand Up @@ -322,10 +333,6 @@ arm64_init(int when)

machdep->uvtop = arm64_uvtop;
machdep->is_uvaddr = arm64_is_uvaddr;
if (kernel_symbol_exists("vabits_user") &&
readmem(symbol_value("vabits_user"), KVADDR,
&value, sizeof(ulong), "vabits_user", RETURN_ON_ERROR))
machdep->machspec->vabits_user = value;
machdep->eframe_search = arm64_eframe_search;
machdep->back_trace = arm64_back_trace_cmd;
machdep->in_alternate_stack = arm64_in_alternate_stack;
Expand Down Expand Up @@ -378,8 +385,24 @@ arm64_init(int when)
else
machdep->max_physmem_bits = _MAX_PHYSMEM_BITS;
}

ms = machdep->machspec;

if (CRASHDEBUG(1)) {
if (ms->VA_BITS_ACTUAL) {
fprintf(fp, "CONFIG_ARM64_VA_BITS: %ld\n", ms->CONFIG_ARM64_VA_BITS);
fprintf(fp, " VA_BITS_ACTUAL: %ld\n", ms->VA_BITS_ACTUAL);
fprintf(fp, "(calculated) VA_BITS: %ld\n", ms->VA_BITS);
fprintf(fp, " PAGE_OFFSET: %lx\n", ARM64_PAGE_OFFSET_ACTUAL);
fprintf(fp, " VA_START: %lx\n", ms->VA_START);
fprintf(fp, " modules: %lx - %lx\n", ms->modules_vaddr, ms->modules_end);
fprintf(fp, " vmalloc: %lx - %lx\n", ms->vmalloc_start_addr, ms->vmalloc_end);
fprintf(fp, "kernel image: %lx - %lx\n", ms->kimage_text, ms->kimage_end);
fprintf(fp, " vmemmap: %lx - %lx\n\n", ms->vmemmap_vaddr, ms->vmemmap_end);
}
}


if (THIS_KERNEL_VERSION >= LINUX(4,0,0)) {
ms->__SWP_TYPE_BITS = 6;
ms->__SWP_TYPE_SHIFT = 2;
Expand Down Expand Up @@ -625,9 +648,15 @@ arm64_dump_machdep_table(ulong arg)

fprintf(fp, " machspec: %lx\n", (ulong)ms);
fprintf(fp, " VA_BITS: %ld\n", ms->VA_BITS);
fprintf(fp, " vabits_user: ");
if (ms->vabits_user)
fprintf(fp, "%ld\n", ms->vabits_user);
fprintf(fp, " CONFIG_ARM64_VA_BITS: %ld\n", ms->CONFIG_ARM64_VA_BITS);
fprintf(fp, " VA_START: ");
if (ms->VA_START)
fprintf(fp, "%lx\n", ms->VA_START);
else
fprintf(fp, "(unused)\n");
fprintf(fp, " VA_BITS_ACTUAL: ");
if (ms->VA_BITS_ACTUAL)
fprintf(fp, "%ld\n", ms->VA_BITS_ACTUAL);
else
fprintf(fp, "(unused)\n");
fprintf(fp, " userspace_top: %016lx\n", ms->userspace_top);
Expand Down Expand Up @@ -716,12 +745,12 @@ arm64_parse_machdep_arg_l(char *argstring, char *param, ulong *value)
int flags = RETURN_ON_ERROR | QUIET;
int err = 0;

if (megabytes) {
if (STRNEQ(argstring, "max_physmem_bits")) {
*value = dtol(p, flags, &err);
} else if (megabytes) {
*value = dtol(p, flags, &err);
if (!err)
*value = MEGABYTES(*value);
} else if (STRNEQ(argstring, "max_physmem_bits")) {
*value = dtol(p, flags, &err);
} else {
*value = htol(p, flags, &err);
}
Expand Down Expand Up @@ -3416,8 +3445,8 @@ arm64_display_machine_stats(void)
fprintf(fp, " HZ: %d\n", machdep->hz);
fprintf(fp, " PAGE SIZE: %d\n", PAGESIZE());
fprintf(fp, "KERNEL VIRTUAL BASE: %lx\n", machdep->machspec->page_offset);
fprintf(fp, "KERNEL VMALLOC BASE: %lx\n", machdep->machspec->vmalloc_start_addr);
fprintf(fp, "KERNEL MODULES BASE: %lx\n", machdep->machspec->modules_vaddr);
fprintf(fp, "KERNEL VMALLOC BASE: %lx\n", machdep->machspec->vmalloc_start_addr);
fprintf(fp, "KERNEL VMEMMAP BASE: %lx\n", machdep->machspec->vmemmap_vaddr);
fprintf(fp, " KERNEL STACK SIZE: %ld\n", STACKSIZE());
if (machdep->machspec->irq_stack_size) {
Expand Down Expand Up @@ -3684,6 +3713,9 @@ arm64_IS_VMALLOC_ADDR(ulong vaddr)
(vaddr <= machdep->machspec->kimage_end))
return FALSE;

if (ms->VA_START && (vaddr >= ms->VA_START))
return TRUE;

return ((vaddr >= ms->vmalloc_start_addr && vaddr <= ms->vmalloc_end) ||
((machdep->flags & VMEMMAP) &&
(vaddr >= ms->vmemmap_vaddr && vaddr <= ms->vmemmap_end)) ||
Expand All @@ -3695,9 +3727,36 @@ arm64_calc_VA_BITS(void)
{
int bitval;
struct syment *sp;
ulong value;
ulong vabits_actual, value;
char *string;

if ((string = pc->read_vmcoreinfo("NUMBER(VA_BITS)"))) {
value = atol(string);
free(string);
machdep->machspec->CONFIG_ARM64_VA_BITS = value;
}

if (kernel_symbol_exists("vabits_actual")) {
if (pc->flags & PROC_KCORE) {
vabits_actual = symbol_value_from_proc_kallsyms("vabits_actual");
if ((vabits_actual != BADVAL) && (READMEM(pc->mfd, &value, sizeof(ulong),
vabits_actual, KCORE_USE_VADDR) > 0)) {
if (CRASHDEBUG(1))
fprintf(fp,
"/proc/kcore: vabits_actual: %ld\n", value);
machdep->machspec->VA_BITS_ACTUAL = value;
machdep->machspec->VA_BITS = value;
machdep->machspec->VA_START = _VA_START(machdep->machspec->VA_BITS_ACTUAL);
} else
error(FATAL, "/proc/kcore: cannot read vabits_actual\n");
} else if (ACTIVE())
error(FATAL, "cannot determine VA_BITS_ACTUAL: please use /proc/kcore\n");
else
error(FATAL, "cannot determine VA_BITS_ACTUAL\n");

return;
}

if (!(sp = symbol_search("swapper_pg_dir")) &&
!(sp = symbol_search("idmap_pg_dir")) &&
!(sp = symbol_search("_text")) &&
Expand Down Expand Up @@ -3726,16 +3785,12 @@ arm64_calc_VA_BITS(void)
/*
* Verify against dumpfiles that export VA_BITS in vmcoreinfo
*/
if ((string = pc->read_vmcoreinfo("NUMBER(VA_BITS)"))) {
value = atol(string);
free(string);
if (machdep->machspec->VA_BITS != value) {
error(WARNING, "VA_BITS: calculated: %ld vmcoreinfo: %ld\n",
machdep->machspec->VA_BITS, value);
machdep->machspec->VA_BITS = value;
}
}

if (machdep->machspec->CONFIG_ARM64_VA_BITS &&
(machdep->machspec->VA_BITS != machdep->machspec->CONFIG_ARM64_VA_BITS)) {
error(WARNING, "VA_BITS: calculated: %ld vmcoreinfo: %ld\n",
machdep->machspec->VA_BITS, machdep->machspec->CONFIG_ARM64_VA_BITS);
machdep->machspec->VA_BITS = machdep->machspec->CONFIG_ARM64_VA_BITS;
}

if (CRASHDEBUG(1))
fprintf(fp, "VA_BITS: %ld\n", machdep->machspec->VA_BITS);
Expand All @@ -3753,6 +3808,15 @@ arm64_calc_VA_BITS(void)
*
* Since VMEMMAP_SIZE is dependent upon the size of a struct page,
* the two ranges cannot be determined until POST_GDB.
*
* Since 52-bit VA was introduced:
*
* #define STRUCT_PAGE_MAX_SHIFT 6
* #define VMEMMAP_SIZE (UL(1) << (VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT))
* #define VMEMMAP_START (-VMEMMAP_SIZE)
* #define VMALLOC_START (MODULES_END)
* #define VMALLOC_END (- PUD_SIZE - VMEMMAP_SIZE - SZ_64K)
* #define vmemmap ((struct page *)VMEMMAP_START - (memstart_addr >> PAGE_SHIFT))
*/

#define ALIGN(x, a) __ALIGN_KERNEL((x), (a))
Expand All @@ -3764,10 +3828,18 @@ static void
arm64_calc_virtual_memory_ranges(void)
{
struct machine_specific *ms = machdep->machspec;
ulong vmemmap_start, vmemmap_end, vmemmap_size;
ulong vmalloc_end;
ulong value, vmemmap_start, vmemmap_end, vmemmap_size, vmalloc_end;
char *string;
ulong PUD_SIZE = UNINITIALIZED;

if (!machdep->machspec->CONFIG_ARM64_VA_BITS) {
if ((string = pc->read_vmcoreinfo("NUMBER(VA_BITS)"))) {
value = atol(string);
free(string);
machdep->machspec->CONFIG_ARM64_VA_BITS = value;
}
}

if (THIS_KERNEL_VERSION < LINUX(3,17,0)) /* use original hardwired values */
return;

Expand All @@ -3786,8 +3858,19 @@ arm64_calc_virtual_memory_ranges(void)
break;
}

if (machdep->flags & NEW_VMEMMAP)
#define STRUCT_PAGE_MAX_SHIFT 6

if (ms->VA_BITS_ACTUAL) {
vmemmap_size = (1UL) << (ms->CONFIG_ARM64_VA_BITS - machdep->pageshift - 1 + STRUCT_PAGE_MAX_SHIFT);
vmalloc_end = (- PUD_SIZE - vmemmap_size - KILOBYTES(64));
vmemmap_start = (-vmemmap_size);
ms->vmalloc_end = vmalloc_end - 1;
ms->vmemmap_vaddr = vmemmap_start;
ms->vmemmap_end = -1;
return;
}

if (machdep->flags & NEW_VMEMMAP)
vmemmap_size = 1UL << (ms->VA_BITS - machdep->pageshift - 1
+ STRUCT_PAGE_MAX_SHIFT);
else
Expand All @@ -3811,7 +3894,7 @@ arm64_calc_virtual_memory_ranges(void)
static int
arm64_is_uvaddr(ulong addr, struct task_context *tc)
{
return (addr < ARM64_USERSPACE_TOP);
return (addr < machdep->machspec->userspace_top);
}


Expand Down
12 changes: 11 additions & 1 deletion defs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3139,9 +3139,17 @@ typedef signed int s32;
*/
#define ARM64_VA_START ((0xffffffffffffffffUL) \
<< machdep->machspec->VA_BITS)
#define _VA_START(va) ((0xffffffffffffffffUL) - \
((1UL) << ((va) - 1)) + 1)
#define TEXT_OFFSET_MASK (~((MEGABYTES(2UL))-1))

#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) \
<< (machdep->machspec->VA_BITS - 1))
#define ARM64_PAGE_OFFSET_ACTUAL ((0xffffffffffffffffUL) \
- ((1UL) << machdep->machspec->VA_BITS_ACTUAL) + 1)

#define ARM64_USERSPACE_TOP ((1UL) << machdep->machspec->VA_BITS)
#define ARM64_USERSPACE_TOP_ACTUAL ((1UL) << machdep->machspec->VA_BITS_ACTUAL)

/* only used for v4.6 or later */
#define ARM64_MODULES_VSIZE MEGABYTES(128)
Expand Down Expand Up @@ -3244,7 +3252,9 @@ struct machine_specific {
ulong kern_eframe_offset;
ulong machine_kexec_start;
ulong machine_kexec_end;
ulong vabits_user;
ulong VA_BITS_ACTUAL;
ulong CONFIG_ARM64_VA_BITS;
ulong VA_START;
};

struct arm64_stackframe {
Expand Down

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