From: Bhupesh Sharma <bhsharma@redhat.com>

Date: Wed, 6 Feb 2019 12:31:29 +0530

Subject: [PATCH] makedumpfile/arm64: Add support for ARMv8.2-LVA (52-bit

 user-space VA support)

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 extension in the

kernel via a CONFIG flag (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 user-space VA 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 are

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):

  #define PTRS_PER_PGD          (1 << (MAX_USER_VA_BITS - PGDIR_SHIFT))

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@redhat.com>

---

 arch/arm64.c   | 109 ++++++++++++++++++++++++++++++++++++++++++---------------

 makedumpfile.c |   2 ++

 makedumpfile.h |   1 +

 3 files changed, 83 insertions(+), 29 deletions(-)

diff --git a/makedumpfile-1.6.6/arch/arm64.c b/makedumpfile-1.6.6/arch/arm64.c

index 0535193..5fcf59d 100644

--- a/makedumpfile-1.6.6/arch/arm64.c

+++ b/makedumpfile-1.6.6/arch/arm64.c

@@ -41,6 +41,7 @@ typedef struct {

 static int pgtable_level;

 static int va_bits;

+static int max_user_va_bits;

 static unsigned long kimage_voffset;

 #define SZ_4K			(4 * 1024)

@@ -61,7 +62,7 @@ static unsigned long kimage_voffset;

 #define PAGE_MASK		(~(PAGESIZE() - 1))

 #define PGDIR_SHIFT		((PAGESHIFT() - 3) * pgtable_level + 3)

-#define PTRS_PER_PGD		(1 << (va_bits - PGDIR_SHIFT))

+#define PTRS_PER_PGD		(1 << ((max_user_va_bits) - PGDIR_SHIFT))

 #define PUD_SHIFT		get_pud_shift_arm64()

 #define PUD_SIZE		(1UL << PUD_SHIFT)

 #define PUD_MASK		(~(PUD_SIZE - 1))

@@ -73,6 +74,10 @@ static unsigned long kimage_voffset;

 #define PTRS_PER_PMD		PTRS_PER_PTE

 #define PAGE_PRESENT		(1 << 0)

+

+/*

+ * Section address mask and size definitions.

+ */

 #define SECTIONS_SIZE_BITS	30

 /* Highest possible physical address supported */

 #define PHYS_MASK_SHIFT		48

@@ -284,14 +289,83 @@ 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);

+

+	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)

 {

 	/* 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;

+

+	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");

@@ -330,34 +404,11 @@ 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;

-	DEBUG_MSG("va_bits      : %d\n", va_bits);

-	DEBUG_MSG("page_offset  : %lx\n", info->page_offset);

+	get_page_offset_arm64();

 	return TRUE;

 }

diff --git a/makedumpfile-1.6.6/makedumpfile.c b/makedumpfile-1.6.6/makedumpfile.c

index d76a435..c8906b5 100644

--- a/makedumpfile-1.6.6/makedumpfile.c

+++ b/makedumpfile-1.6.6/makedumpfile.c

@@ -2313,6 +2313,7 @@ write_vmcoreinfo_data(void)

 	WRITE_NUMBER("HUGETLB_PAGE_DTOR", HUGETLB_PAGE_DTOR);

 #ifdef __aarch64__

+	WRITE_NUMBER("MAX_USER_VA_BITS", MAX_USER_VA_BITS);

 	WRITE_NUMBER("VA_BITS", VA_BITS);

 	WRITE_NUMBER_UNSIGNED("PHYS_OFFSET", PHYS_OFFSET);

 	WRITE_NUMBER_UNSIGNED("kimage_voffset", kimage_voffset);

@@ -2719,6 +2720,7 @@ read_vmcoreinfo(void)

 	READ_NUMBER("phys_base", phys_base);

 	READ_NUMBER("KERNEL_IMAGE_SIZE", KERNEL_IMAGE_SIZE);

 #ifdef __aarch64__

+	READ_NUMBER("MAX_USER_VA_BITS", MAX_USER_VA_BITS);

 	READ_NUMBER("VA_BITS", VA_BITS);

 	READ_NUMBER_UNSIGNED("PHYS_OFFSET", PHYS_OFFSET);

 	READ_NUMBER_UNSIGNED("kimage_voffset", kimage_voffset);

diff --git a/makedumpfile-1.6.6/makedumpfile.h b/makedumpfile-1.6.6/makedumpfile.h

index 24b2f69..cccb52a 100644

--- a/makedumpfile-1.6.6/makedumpfile.h

+++ b/makedumpfile-1.6.6/makedumpfile.h

@@ -1937,6 +1937,7 @@ struct number_table {

 	long	phys_base;

 	long	KERNEL_IMAGE_SIZE;

 #ifdef __aarch64__

+	long 	MAX_USER_VA_BITS;

 	long 	VA_BITS;

 	unsigned long	PHYS_OFFSET;

 	unsigned long	kimage_voffset;

-- 

2.7.5