Hi Kazu,
On 02/12/2019 03:33 AM, Kazuhito Hagio wrote:
Hi Bhupesh,
On 2/7/2019 2:52 PM, Bhupesh Sharma wrote:
With ARMv8.2-LVA architecture extension availability, arm64 hardware
which supports this extension can support upto 52-bit virtual
addresses. It is specially useful for having a 52-bit user-space virtual
address space while the kernel can still retain 48-bit virtual
addresses.
Since at the moment we enable the support of this extensions in the
kernel via a CONFIG flags (CONFIG_ARM64_USER_VA_BITS_52), so there are
no clear mechanisms in user-space to determine this CONFIG
flag value and use it to determine the PA address range values.
'makedumpfile' can instead use 'MAX_USER_VA_BITS' value to
determine the maximum virtual physical address supported by user-space.
If 'MAX_USER_VA_BITS' value is greater than 'VA_BITS' than we might be
running a use-case where user-space is 52-bit and underlying kernel is
still 48-bit. The increased 'PTRS_PER_PGD' value for such cases can then
be calculated as is done by the underlying kernel (see kernel file
'arch/arm64/include/asm/pgtable-hwdef.h' for details):
Thank you for the patch.
I can't test the config yet, but this looks necessary.
I am sorry, this review email somehow did not show up in my inbox.
I have sent a kernel patch upstream to add 'MAX_USER_VA_BITS' to
vmcoreinfo for arm64 (see [0]).
This patch is in accordance with ARMv8 Architecture Reference Manual
version D.a
[0].
http://lists.infradead.org/pipermail/kexec/2019-February/022411.html
Signed-off-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx>
---
arch/arm64.c | 105 +++++++++++++++++++++++++++++++++++++++++----------------
makedumpfile.c | 2 ++
makedumpfile.h | 1 +
3 files changed, 79 insertions(+), 29 deletions(-)
diff --git a/arch/arm64.c b/arch/arm64.c
index a1db7dc63107..b522e93f4e80 100644
--- a/arch/arm64.c
+++ b/arch/arm64.c
@@ -47,6 +47,7 @@ typedef struct {
static int lpa_52_bit_support_available;
static int pgtable_level;
static int va_bits;
+static int max_user_va_bits;
static unsigned long kimage_voffset;
#define SZ_4K 4096
@@ -145,7 +146,7 @@ get_page_table_level_arm64(void)
#define PGDIR_SHIFT ARM64_HW_PGTABLE_LEVEL_SHIFT(4 - (get_page_table_level_arm64()))
#define PGDIR_SIZE (_AC(1, UL) << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE-1))
-#define PTRS_PER_PGD (1 << ((va_bits) - PGDIR_SHIFT))
+#define PTRS_PER_PGD (1 << ((max_user_va_bits) - PGDIR_SHIFT))
/*
* Section address mask and size definitions.
@@ -478,6 +479,46 @@ get_stext_symbol(void)
return(found ? kallsym : FALSE);
}
+static int
+get_va_bits_from_stext_arm64(void)
+{
+ ulong _stext;
+
+ _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;
+ }
+
+ DEBUG_MSG("va_bits : %d\n", va_bits);
Please add "(_stext)" to the end of line for debugging.
Ok, will address in v3.
+
+ return TRUE;
+}
+
+static void
+get_page_offset_arm64(void)
+{
+ info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
+
+ DEBUG_MSG("page_offset : %lx\n", info->page_offset);
+}
+
int
get_machdep_info_arm64(void)
{
@@ -493,8 +534,37 @@ 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 (NUMBER(VA_BITS) != NOT_FOUND_NUMBER) {
+ va_bits = NUMBER(VA_BITS);
+ DEBUG_MSG("va_bits : %d (vmcoreinfo)\n",
+ va_bits);
+ }
+
+ /* Check if va_bits is still not initialized. If still 0, call
+ * get_versiondep_info() to initialize the same from _stext
+ * symbol.
+ */
if (!va_bits)
- get_versiondep_info_arm64();
+ if (get_va_bits_from_stext_arm64() == ERROR)
+ return ERROR;
These ERRORs should be FALSE.
Ok, will address in v3.
+
+ get_page_offset_arm64();
+
+ if (NUMBER(MAX_USER_VA_BITS) != NOT_FOUND_NUMBER) {
+ max_user_va_bits = NUMBER(MAX_USER_VA_BITS);
+ DEBUG_MSG("max_user_va_bits : %d (vmcoreinfo)\n",
+ max_user_va_bits);
+ }
+
+ /* Check if max_user_va_bits is still not initialized.
+ * If still 0, its not available in vmcoreinfo and its
+ * safe to initialize it with va_bits.
+ */
+ if (!max_user_va_bits) {
+ max_user_va_bits = va_bits;
+ DEBUG_MSG("max_user_va_bits : %d (default = va_bits)\n",
+ max_user_va_bits);
+ }
if (!calculate_plat_config()) {
ERRMSG("Can't determine platform config values\n");
@@ -533,34 +603,11 @@ get_xen_info_arm64(void)
int
get_versiondep_info_arm64(void)
{
- ulong _stext;
-
- _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;
- }
-
- info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
+ if (!va_bits)
+ if (get_va_bits_from_stext_arm64() == ERROR)
+ return ERROR;
Same as above.
Ok, will address in v3.
Thanks,
Bhupesh
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