[PATCH V2 0/2] kexec-tools: arm64: Enable D-cache in purgatory

[PATCH V2 0/2] kexec-tools: arm64: Enable D-cache in purgatory

[Pratyush Anand]

It takes more that 2 minutes to verify SHA in purgatory when vmlinuz image
is around 13MB and initramfs is around 30MB. It takes more than 20 second
even when we have -O2 optimization enabled. However, if dcache is enabled
during purgatory execution then, it takes just a second in SHA
verification.

Therefore, these patches adds support for dcache enabling facility during
purgatory execution.

Although I have simplified the logic a bit now, however I understand that
there are reservations for introducing this complexity for gaining few
seconding of execution time during kexec or crash reboot.  But, I believe
if d-cache enabling code is stable enough then there should not be any
hindrances to accept it. So, please give it a try with your platform and
let me know if you see any issue or it does not work. I am still open to
improve it further if needed.

Changes since V1:
	- Moved page table creation logic from purgatory to kexec code.
	- Only 4K page table is supported, with 48 bit VA and 2M block size
	- if platform supports a 4K page size, then D-cache is always
	  enabled now.
 
Pratyush Anand (2):
  kexec: arm64: create identity page table to be used in purgatory
  arm64: enable d-cache support during purgatory sha verification

 kexec/arch/arm64/kexec-arm64.c         | 152 ++++++++++++++++++
 purgatory/arch/arm64/Makefile          |   1 +
 purgatory/arch/arm64/cache.S           | 281 +++++++++++++++++++++++++++++++++
 purgatory/arch/arm64/purgatory-arm64.c |   5 +
 4 files changed, 439 insertions(+)
 create mode 100644 purgatory/arch/arm64/cache.S

-- 
2.7.4

[PATCH V2 1/2] kexec: arm64: create identity page table to be used in purgatory

[Pratyush Anand]

Purgatory sha verification is very slow when D-cache is not enabled there.
We need to enable MMU as well to enable D-Cache.Therefore,we need to an
identity mapped page table in purgatory.

Since debugging is very difficult in purgatory therefore we prefer to do as
much work as possible in kexec.

This patch prepares page table for purgatory in advance. We support only 4K
page table,because it will be available on most of the platform. This page
table is passed to the purgatory as a new segment.

VA bit is fixed as 48, page table level is 3 where 3rd level page table
contains 2M block entries.

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
 kexec/arch/arm64/kexec-arm64.c | 152 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)

diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
index 04fd3968bb52..c2c8ff1b6940 100644
--- a/kexec/arch/arm64/kexec-arm64.c
+++ b/kexec/arch/arm64/kexec-arm64.c
@@ -24,6 +24,45 @@
 #include "kexec-syscall.h"
 #include "arch/options.h"
 
+/*
+ * kexec creates identity page table to be used in purgatory so that
+ * dcache verification becomes faster.
+ *
+ * These are the definitions to be used by page table creation routine.
+ *
+ * Only 4K page table, 3 level, 2M block mapping, 48bit VA is supported
+ */
+#define PGDIR_SHIFT		39
+#define PUD_SHIFT		30
+#define PMD_SHIFT		21
+#define PTRS_PER_PGD		0x1FF
+#define PTRS_PER_PUD		0x1FF
+#define PTRS_PER_PMD		0x1FF
+#define PMD_TYPE_TABLE		(3UL << 0)
+#define PMD_TYPE_SECT		(1UL << 0)
+#define PMD_SECT_AF		(1UL << 10)
+#define PMD_ATTRINDX(t)		((unsigned long)(t) << 2)
+#define MT_NORMAL		4
+#define PMD_FLAGS_NORMAL	(PMD_TYPE_SECT | PMD_SECT_AF)
+#define MMU_FLAGS_NORMAL	(PMD_ATTRINDX(MT_NORMAL) | PMD_FLAGS_NORMAL)
+#define SECTION_SIZE		(2 * 1024 * 1024)
+#define PAGE_SIZE		(4 * 1024)
+/* Since we are using 3 level of page tables, therefore minimum number of
+ * table will be 3. Most likely we will never need more than 3. Each entry
+ * in level 3 page table can map 2MB memory area. Thus a level 3 page table
+ * indexed by bit 29:21 can map a total of 1G memory area. Therefore, if
+ * any segment crosses 1G boundary, then we will need one more level 3
+ * table. Similarly, level 2 page table indexed by bit 38:30 can map a
+ * total of 512G memory area. If segment addresses are more than 512G apart
+ * then we will need two more table for each such block. We do not expect
+ * any memory segment to cross 512G boundary, however if we will ever wish
+ * to support uart debugging in purgatory then that might cross the
+ * boundary and therefore additional 2 more table space. Thus we will need
+ * maximum of 6 table space.
+ */
+#define MAX_PGTBLE_SZ	(6 * 4096)
+static int next_tbl_cnt = 1;
+
 /* Global varables the core kexec routines expect. */
 
 unsigned char reuse_initrd;
@@ -316,6 +355,117 @@ unsigned long arm64_locate_kernel_segment(struct kexec_info *info)
 	return hole;
 }
 
+static unsigned long *create_table_entry(unsigned long *pgtbl_buf,
+		unsigned long pgtbl_mem, unsigned long *tbl,
+		unsigned long virt, int shift,
+		unsigned long ptrs)
+{
+	unsigned long index, desc, offset;
+
+	index = (virt >> shift) & ptrs;
+	/* check if we have allocated a table already for this index */
+	if (tbl[index]) {
+		/*
+		 * table index will have entry as per purgatory page table
+		 * memory. Find out corresponding buffer address of table.
+		 */
+		desc = tbl[index] & ~3UL;
+		offset = desc - pgtbl_mem;
+		return &pgtbl_buf[offset >> 3];
+	}
+
+	/*
+	 * Always write page table content as per page table memory allocated
+	 * for purgaory area, but return corresponding buffer area alloced
+	 * in kexec
+	 */
+	if (next_tbl_cnt > 5)
+		die("%s: No more memory for page table\n", __func__);
+
+	tbl[index] = (pgtbl_mem + PAGE_SIZE * next_tbl_cnt) | PMD_TYPE_TABLE;
+
+	return &pgtbl_buf[(next_tbl_cnt++ * PAGE_SIZE) >> 3];
+}
+
+static void craete_block_entry(unsigned long *tbl, unsigned long flags,
+		unsigned long phys, unsigned long virt)
+{
+	unsigned long index;
+	unsigned long desc;
+
+	index = (virt >> PMD_SHIFT) & PTRS_PER_PMD;
+	desc = (phys >> PMD_SHIFT) << PMD_SHIFT;
+	desc |= flags;
+	tbl[index] = desc;
+}
+
+static void create_identity_entry(unsigned long *pgtbl_buf,
+		unsigned long pgtbl_mem, unsigned long virt,
+		unsigned long flags)
+{
+	unsigned long *tbl = pgtbl_buf;
+
+	tbl = create_table_entry(pgtbl_buf, pgtbl_mem, tbl, virt,
+			PGDIR_SHIFT, PTRS_PER_PGD);
+	tbl = create_table_entry(pgtbl_buf, pgtbl_mem, tbl, virt,
+			PUD_SHIFT, PTRS_PER_PUD);
+	craete_block_entry(tbl, flags, virt, virt);
+}
+
+/**
+ * arm64_create_pgtbl_segment - Create page table segments to be used by
+ * purgatory. Page table will have entries to access memory area of all
+ * those segments which becomes part of sha verification in purgatory.
+ * Additionaly, we also create page table for purgatory segment as well.
+ */
+
+static int arm64_create_pgtbl_segment(struct kexec_info *info,
+		unsigned long hole_min, unsigned long hole_max)
+{
+	unsigned long *pgtbl_buf;
+	int i;
+	unsigned long mstart, mend, pgtbl_mem;
+	unsigned long purgatory_base, purgatory_len;
+
+	pgtbl_buf = xmalloc(MAX_PGTBLE_SZ);
+	memset(pgtbl_buf, 0, MAX_PGTBLE_SZ);
+	pgtbl_mem = add_buffer_phys_virt(info, pgtbl_buf, MAX_PGTBLE_SZ,
+			MAX_PGTBLE_SZ, PAGE_SIZE, hole_min, hole_max, 1, 0);
+	for (i = 0; i < info->nr_segments; i++) {
+		if (info->segment[i].mem == (void *)info->rhdr.rel_addr) {
+			purgatory_base = (unsigned long)info->segment[i].mem;
+			purgatory_len = info->segment[i].memsz;
+		}
+		mstart = (unsigned long)info->segment[i].mem;
+		mend = mstart + info->segment[i].memsz;
+		mstart &= ~(SECTION_SIZE - 1);
+		while (mstart < mend) {
+			create_identity_entry(pgtbl_buf, pgtbl_mem,
+					mstart, MMU_FLAGS_NORMAL);
+			mstart += SECTION_SIZE;
+		}
+	}
+
+	/* we will need pgtble_base in purgatory for enabling d-cache */
+	elf_rel_set_symbol(&info->rhdr, "pgtble_base", &pgtbl_mem,
+		sizeof(pgtbl_mem));
+	/*
+	 * We need to disable d-cache before we exit from purgatory.
+	 * Since, only dcache flush by VAs is recomeneded, therefore we
+	 * will also need memory location of all those area which will be
+	 * accessed in purgatory with enabled d-cache. sha256_regions
+	 * already have start and length for all the segments except
+	 * purgatory. Therefore, we will need to pass start and length of
+	 * purgatory additionaly.
+	 */
+	elf_rel_set_symbol(&info->rhdr, "purgatory_base", &purgatory_base,
+		sizeof(purgatory_base));
+	elf_rel_set_symbol(&info->rhdr, "purgatory_len", &purgatory_len,
+		sizeof(purgatory_len));
+
+	return 0;
+}
+
 /**
  * arm64_load_other_segments - Prepare the dtb, initrd and purgatory segments.
  */
@@ -423,6 +573,8 @@ int arm64_load_other_segments(struct kexec_info *info,
 	elf_rel_set_symbol(&info->rhdr, "arm64_dtb_addr", &dtb_base,
 		sizeof(dtb_base));
 
+	arm64_create_pgtbl_segment(info, hole_min, hole_max);
+
 	return 0;
 }
 
-- 
2.7.4

[PATCH V2 1/2] kexec: arm64: create identity page table to be used in purgatory

[Maxim Uvarov]

2016-12-19 10:13 GMT+03:00 Pratyush Anand <panand@redhat.com>:
> Purgatory sha verification is very slow when D-cache is not enabled there.
> We need to enable MMU as well to enable D-Cache.Therefore,we need to an
> identity mapped page table in purgatory.
>
> Since debugging is very difficult in purgatory therefore we prefer to do as
> much work as possible in kexec.
>
> This patch prepares page table for purgatory in advance. We support only 4K
> page table,because it will be available on most of the platform. This page
> table is passed to the purgatory as a new segment.
>
> VA bit is fixed as 48, page table level is 3 where 3rd level page table
> contains 2M block entries.
>
> Signed-off-by: Pratyush Anand <panand@redhat.com>
> ---
>  kexec/arch/arm64/kexec-arm64.c | 152 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 152 insertions(+)
>
> diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
> index 04fd3968bb52..c2c8ff1b6940 100644
> --- a/kexec/arch/arm64/kexec-arm64.c
> +++ b/kexec/arch/arm64/kexec-arm64.c
> @@ -24,6 +24,45 @@
>  #include "kexec-syscall.h"
>  #include "arch/options.h"
>
> +/*
> + * kexec creates identity page table to be used in purgatory so that
> + * dcache verification becomes faster.
> + *
> + * These are the definitions to be used by page table creation routine.
> + *
> + * Only 4K page table, 3 level, 2M block mapping, 48bit VA is supported
> + */
> +#define PGDIR_SHIFT            39
> +#define PUD_SHIFT              30
> +#define PMD_SHIFT              21
> +#define PTRS_PER_PGD           0x1FF
> +#define PTRS_PER_PUD           0x1FF
> +#define PTRS_PER_PMD           0x1FF
> +#define PMD_TYPE_TABLE         (3UL << 0)
> +#define PMD_TYPE_SECT          (1UL << 0)
> +#define PMD_SECT_AF            (1UL << 10)
> +#define PMD_ATTRINDX(t)                ((unsigned long)(t) << 2)
> +#define MT_NORMAL              4
> +#define PMD_FLAGS_NORMAL       (PMD_TYPE_SECT | PMD_SECT_AF)
> +#define MMU_FLAGS_NORMAL       (PMD_ATTRINDX(MT_NORMAL) | PMD_FLAGS_NORMAL)
> +#define SECTION_SIZE           (2 * 1024 * 1024)
> +#define PAGE_SIZE              (4 * 1024)
> +/* Since we are using 3 level of page tables, therefore minimum number of
> + * table will be 3. Most likely we will never need more than 3. Each entry
> + * in level 3 page table can map 2MB memory area. Thus a level 3 page table
> + * indexed by bit 29:21 can map a total of 1G memory area. Therefore, if
> + * any segment crosses 1G boundary, then we will need one more level 3
> + * table. Similarly, level 2 page table indexed by bit 38:30 can map a
> + * total of 512G memory area. If segment addresses are more than 512G apart
> + * then we will need two more table for each such block. We do not expect
> + * any memory segment to cross 512G boundary, however if we will ever wish
> + * to support uart debugging in purgatory then that might cross the
> + * boundary and therefore additional 2 more table space. Thus we will need
> + * maximum of 6 table space.
> + */
> +#define MAX_PGTBLE_SZ  (6 * 4096)
> +static int next_tbl_cnt = 1;
> +
>  /* Global varables the core kexec routines expect. */
>
>  unsigned char reuse_initrd;
> @@ -316,6 +355,117 @@ unsigned long arm64_locate_kernel_segment(struct kexec_info *info)
>         return hole;
>  }
>
> +static unsigned long *create_table_entry(unsigned long *pgtbl_buf,
> +               unsigned long pgtbl_mem, unsigned long *tbl,
> +               unsigned long virt, int shift,
> +               unsigned long ptrs)
> +{
> +       unsigned long index, desc, offset;
> +
> +       index = (virt >> shift) & ptrs;
> +       /* check if we have allocated a table already for this index */
> +       if (tbl[index]) {
> +               /*
> +                * table index will have entry as per purgatory page table
> +                * memory. Find out corresponding buffer address of table.
> +                */
> +               desc = tbl[index] & ~3UL;
> +               offset = desc - pgtbl_mem;
> +               return &pgtbl_buf[offset >> 3];
> +       }
> +
> +       /*
> +        * Always write page table content as per page table memory allocated
> +        * for purgaory area, but return corresponding buffer area alloced
> +        * in kexec
> +        */
> +       if (next_tbl_cnt > 5)
> +               die("%s: No more memory for page table\n", __func__);
> +
> +       tbl[index] = (pgtbl_mem + PAGE_SIZE * next_tbl_cnt) | PMD_TYPE_TABLE;
> +
> +       return &pgtbl_buf[(next_tbl_cnt++ * PAGE_SIZE) >> 3];
> +}
> +
> +static void craete_block_entry(unsigned long *tbl, unsigned long flags,

typo in name

> +               unsigned long phys, unsigned long virt)
> +{
> +       unsigned long index;
> +       unsigned long desc;
> +
> +       index = (virt >> PMD_SHIFT) & PTRS_PER_PMD;
> +       desc = (phys >> PMD_SHIFT) << PMD_SHIFT;
> +       desc |= flags;
> +       tbl[index] = desc;
> +}
> +
> +static void create_identity_entry(unsigned long *pgtbl_buf,
> +               unsigned long pgtbl_mem, unsigned long virt,
> +               unsigned long flags)
> +{
> +       unsigned long *tbl = pgtbl_buf;
> +
> +       tbl = create_table_entry(pgtbl_buf, pgtbl_mem, tbl, virt,
> +                       PGDIR_SHIFT, PTRS_PER_PGD);
> +       tbl = create_table_entry(pgtbl_buf, pgtbl_mem, tbl, virt,
> +                       PUD_SHIFT, PTRS_PER_PUD);
> +       craete_block_entry(tbl, flags, virt, virt);
> +}
> +
> +/**
> + * arm64_create_pgtbl_segment - Create page table segments to be used by
> + * purgatory. Page table will have entries to access memory area of all
> + * those segments which becomes part of sha verification in purgatory.
> + * Additionaly, we also create page table for purgatory segment as well.
> + */
> +
> +static int arm64_create_pgtbl_segment(struct kexec_info *info,
> +               unsigned long hole_min, unsigned long hole_max)
> +{
> +       unsigned long *pgtbl_buf;
> +       int i;
> +       unsigned long mstart, mend, pgtbl_mem;
> +       unsigned long purgatory_base, purgatory_len;
> +
> +       pgtbl_buf = xmalloc(MAX_PGTBLE_SZ);
> +       memset(pgtbl_buf, 0, MAX_PGTBLE_SZ);
> +       pgtbl_mem = add_buffer_phys_virt(info, pgtbl_buf, MAX_PGTBLE_SZ,
> +                       MAX_PGTBLE_SZ, PAGE_SIZE, hole_min, hole_max, 1, 0);
> +       for (i = 0; i < info->nr_segments; i++) {
> +               if (info->segment[i].mem == (void *)info->rhdr.rel_addr) {
> +                       purgatory_base = (unsigned long)info->segment[i].mem;
> +                       purgatory_len = info->segment[i].memsz;
> +               }
> +               mstart = (unsigned long)info->segment[i].mem;
> +               mend = mstart + info->segment[i].memsz;
> +               mstart &= ~(SECTION_SIZE - 1);
> +               while (mstart < mend) {
> +                       create_identity_entry(pgtbl_buf, pgtbl_mem,
> +                                       mstart, MMU_FLAGS_NORMAL);
> +                       mstart += SECTION_SIZE;
> +               }
> +       }
> +
> +       /* we will need pgtble_base in purgatory for enabling d-cache */
> +       elf_rel_set_symbol(&info->rhdr, "pgtble_base", &pgtbl_mem,
> +               sizeof(pgtbl_mem));
> +       /*
> +        * We need to disable d-cache before we exit from purgatory.
> +        * Since, only dcache flush by VAs is recomeneded, therefore we
> +        * will also need memory location of all those area which will be
> +        * accessed in purgatory with enabled d-cache. sha256_regions
> +        * already have start and length for all the segments except
> +        * purgatory. Therefore, we will need to pass start and length of
> +        * purgatory additionaly.
> +        */
> +       elf_rel_set_symbol(&info->rhdr, "purgatory_base", &purgatory_base,
> +               sizeof(purgatory_base));
> +       elf_rel_set_symbol(&info->rhdr, "purgatory_len", &purgatory_len,
> +               sizeof(purgatory_len));
> +
> +       return 0;
> +}
> +
>  /**
>   * arm64_load_other_segments - Prepare the dtb, initrd and purgatory segments.
>   */
> @@ -423,6 +573,8 @@ int arm64_load_other_segments(struct kexec_info *info,
>         elf_rel_set_symbol(&info->rhdr, "arm64_dtb_addr", &dtb_base,
>                 sizeof(dtb_base));
>
> +       arm64_create_pgtbl_segment(info, hole_min, hole_max);
> +
>         return 0;
>  }
>
> --
> 2.7.4
>
>
> _______________________________________________
> kexec mailing list
> kexec at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec



-- 
Best regards,
Maxim Uvarov

[PATCH V2 1/2] kexec: arm64: create identity page table to be used in purgatory

[Pratyush Anand]

On Monday 19 December 2016 12:51 PM, Maxim Uvarov wrote:
>> +
>> > +static void craete_block_entry(unsigned long *tbl, unsigned long flags,
> typo in name
>

Thanks.
Will fix.

~Pratyush

[PATCH V2 1/2] kexec: arm64: create identity page table to be used in purgatory

[James Morse]

Hi Pratyush,

On 19/12/16 07:13, Pratyush Anand wrote:
> Purgatory sha verification is very slow when D-cache is not enabled there.
> We need to enable MMU as well to enable D-Cache.Therefore,we need to an
> identity mapped page table in purgatory.
> 
> Since debugging is very difficult in purgatory therefore we prefer to do as
> much work as possible in kexec.
> 
> This patch prepares page table for purgatory in advance. We support only 4K
> page table,because it will be available on most of the platform. This page
> table is passed to the purgatory as a new segment.
> 
> VA bit is fixed as 48, page table level is 3 where 3rd level page table
> contains 2M block entries.

> diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
> index 04fd3968bb52..c2c8ff1b6940 100644
> --- a/kexec/arch/arm64/kexec-arm64.c
> +++ b/kexec/arch/arm64/kexec-arm64.c
> @@ -24,6 +24,45 @@
>  #include "kexec-syscall.h"
>  #include "arch/options.h"
>  
> +/*
> + * kexec creates identity page table to be used in purgatory so that
> + * dcache verification becomes faster.
> + *
> + * These are the definitions to be used by page table creation routine.
> + *
> + * Only 4K page table, 3 level, 2M block mapping, 48bit VA is supported
> + */
> +#define PGDIR_SHIFT		39
> +#define PUD_SHIFT		30
> +#define PMD_SHIFT		21
> +#define PTRS_PER_PGD		0x1FF
> +#define PTRS_PER_PUD		0x1FF
> +#define PTRS_PER_PMD		0x1FF

Aren't these 0x200 for 4K pages in the kernel? It looks like you use them as a
mask instead.


> +#define PMD_TYPE_TABLE		(3UL << 0)
> +#define PMD_TYPE_SECT		(1UL << 0)
> +#define PMD_SECT_AF		(1UL << 10)
> +#define PMD_ATTRINDX(t)		((unsigned long)(t) << 2)

> +#define MT_NORMAL		4

This needs to correspond to the part of MAIR that describes the memory type for
'normal'. You define MT_NORMAL again in the next patch, it would be better to
share the definition so they can't be different. (I don't see why you can't use 0!)


> +#define PMD_FLAGS_NORMAL	(PMD_TYPE_SECT | PMD_SECT_AF)
> +#define MMU_FLAGS_NORMAL	(PMD_ATTRINDX(MT_NORMAL) | PMD_FLAGS_NORMAL)

The SH and AP bits are left as zero, which means non-shareable, read/writeable,
(which I think is fine).


> +#define SECTION_SIZE		(2 * 1024 * 1024)
> +#define PAGE_SIZE		(4 * 1024)
> +/* Since we are using 3 level of page tables, therefore minimum number of
> + * table will be 3. Most likely we will never need more than 3. Each entry
> + * in level 3 page table can map 2MB memory area. Thus a level 3 page table
> + * indexed by bit 29:21 can map a total of 1G memory area. Therefore, if
> + * any segment crosses 1G boundary, then we will need one more level 3
> + * table. Similarly, level 2 page table indexed by bit 38:30 can map a
> + * total of 512G memory area. If segment addresses are more than 512G apart
> + * then we will need two more table for each such block. We do not expect
> + * any memory segment to cross 512G boundary, however if we will ever wish
> + * to support uart debugging in purgatory then that might cross the
> + * boundary and therefore additional 2 more table space. Thus we will need
> + * maximum of 6 table space.

Surely we only need 6 page_size table entries if we support uart debugging,
which your 'if we ever' suggests we don't. So surely we only need 3, and a
comment that this needs expanding to 6 if we need to map two distinct areas.


> + */
> +#define MAX_PGTBLE_SZ	(6 * 4096)
> +static int next_tbl_cnt = 1;
> +
>  /* Global varables the core kexec routines expect. */
>  
>  unsigned char reuse_initrd;
> @@ -316,6 +355,117 @@ unsigned long arm64_locate_kernel_segment(struct kexec_info *info)
>  	return hole;
>  }
>  
> +static unsigned long *create_table_entry(unsigned long *pgtbl_buf,
> +		unsigned long pgtbl_mem, unsigned long *tbl,
> +		unsigned long virt, int shift,
> +		unsigned long ptrs)
> +{
> +	unsigned long index, desc, offset;
> +
> +	index = (virt >> shift) & ptrs;
> +	/* check if we have allocated a table already for this index */
> +	if (tbl[index]) {
> +		/*
> +		 * table index will have entry as per purgatory page table
> +		 * memory. Find out corresponding buffer address of table.
> +		 */
> +		desc = tbl[index] & ~3UL;
> +		offset = desc - pgtbl_mem;

wait .. no .. pgtbl_mem is also a guest physical address, so this is fine... its
not obvious at first glance!  You could do with a typedef to make it clear which
addresses are the guests (pgtable_mem) and which are the hosts (pgtable_buf).
Something like phys_addr_t?


> +		return &pgtbl_buf[offset >> 3];
> +	}
> +
> +	/*
> +	 * Always write page table content as per page table memory allocated
> +	 * for purgaory area, but return corresponding buffer area alloced

Nit: purgatory, allocated,

> +	 * in kexec
> +	 */
> +	if (next_tbl_cnt > 5)
> +		die("%s: No more memory for page table\n", __func__);

die()? With a bit of juggling can't we return an error so we never try to enable
the MMU+dcache instead?


> +
> +	tbl[index] = (pgtbl_mem + PAGE_SIZE * next_tbl_cnt) | PMD_TYPE_TABLE;
> +
> +	return &pgtbl_buf[(next_tbl_cnt++ * PAGE_SIZE) >> 3];
> +}
> +
> +static void craete_block_entry(unsigned long *tbl, unsigned long flags,
> +		unsigned long phys, unsigned long virt)

Why have separate phys and virt parameters if all this ever does is idmap?


> +{
> +	unsigned long index;
> +	unsigned long desc;
> +
> +	index = (virt >> PMD_SHIFT) & PTRS_PER_PMD;

Copying the pmd_index() macro would make this clearer.


> +	desc = (phys >> PMD_SHIFT) << PMD_SHIFT;

Looks like you wanted a PMD_MASK.


> +	desc |= flags;
> +	tbl[index] = desc;
> +}
> +
> +static void create_identity_entry(unsigned long *pgtbl_buf,
> +		unsigned long pgtbl_mem, unsigned long virt,
> +		unsigned long flags)
> +{
> +	unsigned long *tbl = pgtbl_buf;
> +
> +	tbl = create_table_entry(pgtbl_buf, pgtbl_mem, tbl, virt,
> +			PGDIR_SHIFT, PTRS_PER_PGD);
> +	tbl = create_table_entry(pgtbl_buf, pgtbl_mem, tbl, virt,
> +			PUD_SHIFT, PTRS_PER_PUD);
> +	craete_block_entry(tbl, flags, virt, virt);

Nit: create

> +}
> +
> +/**
> + * arm64_create_pgtbl_segment - Create page table segments to be used by
> + * purgatory. Page table will have entries to access memory area of all
> + * those segments which becomes part of sha verification in purgatory.
> + * Additionaly, we also create page table for purgatory segment as well.

Nit: additionally,

> + */
> +
> +static int arm64_create_pgtbl_segment(struct kexec_info *info,
> +		unsigned long hole_min, unsigned long hole_max)
> +{
> +	unsigned long *pgtbl_buf;
> +	int i;
> +	unsigned long mstart, mend, pgtbl_mem;
> +	unsigned long purgatory_base, purgatory_len;
> +
> +	pgtbl_buf = xmalloc(MAX_PGTBLE_SZ);
> +	memset(pgtbl_buf, 0, MAX_PGTBLE_SZ);

> +	pgtbl_mem = add_buffer_phys_virt(info, pgtbl_buf, MAX_PGTBLE_SZ,
> +			MAX_PGTBLE_SZ, PAGE_SIZE, hole_min, hole_max, 1, 0);

I want to check what this does, but this all looks like it is doing the right thing.


> +	for (i = 0; i < info->nr_segments; i++) {
> +		if (info->segment[i].mem == (void *)info->rhdr.rel_addr) {
> +			purgatory_base = (unsigned long)info->segment[i].mem;
> +			purgatory_len = info->segment[i].memsz;
> +		}
> +		mstart = (unsigned long)info->segment[i].mem;
> +		mend = mstart + info->segment[i].memsz;
> +		mstart &= ~(SECTION_SIZE - 1);
> +		while (mstart < mend) {
> +			create_identity_entry(pgtbl_buf, pgtbl_mem,
> +					mstart, MMU_FLAGS_NORMAL);
> +			mstart += SECTION_SIZE;
> +		}
> +	}


Thanks,

James

[PATCH V2 1/2] kexec: arm64: create identity page table to be used in purgatory

[Pratyush Anand]

Hi James,

Thanks for your review.

On Tuesday 17 January 2017 10:55 PM, James Morse wrote:
> Hi Pratyush,
>
> On 19/12/16 07:13, Pratyush Anand wrote:
>> Purgatory sha verification is very slow when D-cache is not enabled there.
>> We need to enable MMU as well to enable D-Cache.Therefore,we need to an
>> identity mapped page table in purgatory.
>>
>> Since debugging is very difficult in purgatory therefore we prefer to do as
>> much work as possible in kexec.
>>
>> This patch prepares page table for purgatory in advance. We support only 4K
>> page table,because it will be available on most of the platform. This page
>> table is passed to the purgatory as a new segment.
>>
>> VA bit is fixed as 48, page table level is 3 where 3rd level page table
>> contains 2M block entries.
>
>> diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
>> index 04fd3968bb52..c2c8ff1b6940 100644
>> --- a/kexec/arch/arm64/kexec-arm64.c
>> +++ b/kexec/arch/arm64/kexec-arm64.c
>> @@ -24,6 +24,45 @@
>>  #include "kexec-syscall.h"
>>  #include "arch/options.h"
>>
>> +/*
>> + * kexec creates identity page table to be used in purgatory so that
>> + * dcache verification becomes faster.
>> + *
>> + * These are the definitions to be used by page table creation routine.
>> + *
>> + * Only 4K page table, 3 level, 2M block mapping, 48bit VA is supported
>> + */
>> +#define PGDIR_SHIFT		39
>> +#define PUD_SHIFT		30
>> +#define PMD_SHIFT		21
>> +#define PTRS_PER_PGD		0x1FF
>> +#define PTRS_PER_PUD		0x1FF
>> +#define PTRS_PER_PMD		0x1FF
>
> Aren't these 0x200 for 4K pages in the kernel? It looks like you use them as a
> mask instead.
>

will use definitions as in kernel.

>
>> +#define PMD_TYPE_TABLE		(3UL << 0)
>> +#define PMD_TYPE_SECT		(1UL << 0)
>> +#define PMD_SECT_AF		(1UL << 10)
>> +#define PMD_ATTRINDX(t)		((unsigned long)(t) << 2)
>
>> +#define MT_NORMAL		4
>
> This needs to correspond to the part of MAIR that describes the memory type for
> 'normal'. You define MT_NORMAL again in the next patch, it would be better to
> share the definition so they can't be different. (I don't see why you can't use 0!)

Hummm...Had thought to share the definition, but inclusion of header 
file into purgatory code looked like ugly. But I see 
purgatory/purgatory.c is including "../kexec/kexec-sha256.h". So, 
probably I can do that similarly.

Yes, can use 0 as well, as there is no other memory type now.

>
>
>> +#define PMD_FLAGS_NORMAL	(PMD_TYPE_SECT | PMD_SECT_AF)
>> +#define MMU_FLAGS_NORMAL	(PMD_ATTRINDX(MT_NORMAL) | PMD_FLAGS_NORMAL)
>
> The SH and AP bits are left as zero, which means non-shareable, read/writeable,
> (which I think is fine).
>
>
>> +#define SECTION_SIZE		(2 * 1024 * 1024)
>> +#define PAGE_SIZE		(4 * 1024)
>> +/* Since we are using 3 level of page tables, therefore minimum number of
>> + * table will be 3. Most likely we will never need more than 3. Each entry
>> + * in level 3 page table can map 2MB memory area. Thus a level 3 page table
>> + * indexed by bit 29:21 can map a total of 1G memory area. Therefore, if
>> + * any segment crosses 1G boundary, then we will need one more level 3
>> + * table. Similarly, level 2 page table indexed by bit 38:30 can map a
>> + * total of 512G memory area. If segment addresses are more than 512G apart
>> + * then we will need two more table for each such block. We do not expect
>> + * any memory segment to cross 512G boundary, however if we will ever wish
>> + * to support uart debugging in purgatory then that might cross the
>> + * boundary and therefore additional 2 more table space. Thus we will need
>> + * maximum of 6 table space.
>
> Surely we only need 6 page_size table entries if we support uart debugging,
> which your 'if we ever' suggests we don't. So surely we only need 3, and a
> comment that this needs expanding to 6 if we need to map two distinct areas.
>

OK, will use 3 now and write comments accordingly.

>
>> + */
>> +#define MAX_PGTBLE_SZ	(6 * 4096)
>> +static int next_tbl_cnt = 1;
>> +
>>  /* Global varables the core kexec routines expect. */
>>
>>  unsigned char reuse_initrd;
>> @@ -316,6 +355,117 @@ unsigned long arm64_locate_kernel_segment(struct kexec_info *info)
>>  	return hole;
>>  }
>>
>> +static unsigned long *create_table_entry(unsigned long *pgtbl_buf,
>> +		unsigned long pgtbl_mem, unsigned long *tbl,
>> +		unsigned long virt, int shift,
>> +		unsigned long ptrs)
>> +{
>> +	unsigned long index, desc, offset;
>> +
>> +	index = (virt >> shift) & ptrs;
>> +	/* check if we have allocated a table already for this index */
>> +	if (tbl[index]) {
>> +		/*
>> +		 * table index will have entry as per purgatory page table
>> +		 * memory. Find out corresponding buffer address of table.
>> +		 */
>> +		desc = tbl[index] & ~3UL;
>> +		offset = desc - pgtbl_mem;
>
> wait .. no .. pgtbl_mem is also a guest physical address, so this is fine... its
> not obvious at first glance!  You could do with a typedef to make it clear which
> addresses are the guests (pgtable_mem) and which are the hosts (pgtable_buf).
> Something like phys_addr_t?

so may be host_addr_t and guest_addr_t??

>
>
>> +		return &pgtbl_buf[offset >> 3];
>> +	}
>> +
>> +	/*
>> +	 * Always write page table content as per page table memory allocated
>> +	 * for purgaory area, but return corresponding buffer area alloced
>
> Nit: purgatory, allocated,

ok.

>
>> +	 * in kexec
>> +	 */
>> +	if (next_tbl_cnt > 5)
>> +		die("%s: No more memory for page table\n", __func__);
>
> die()? With a bit of juggling can't we return an error so we never try to enable
> the MMU+dcache instead?
>

OK. can do that.

>
>> +
>> +	tbl[index] = (pgtbl_mem + PAGE_SIZE * next_tbl_cnt) | PMD_TYPE_TABLE;
>> +
>> +	return &pgtbl_buf[(next_tbl_cnt++ * PAGE_SIZE) >> 3];
>> +}
>> +
>> +static void craete_block_entry(unsigned long *tbl, unsigned long flags,
>> +		unsigned long phys, unsigned long virt)
>
> Why have separate phys and virt parameters if all this ever does is idmap?

Agreed.

>
>
>> +{
>> +	unsigned long index;
>> +	unsigned long desc;
>> +
>> +	index = (virt >> PMD_SHIFT) & PTRS_PER_PMD;
>
> Copying the pmd_index() macro would make this clearer.

Right.

>
>
>> +	desc = (phys >> PMD_SHIFT) << PMD_SHIFT;
>
> Looks like you wanted a PMD_MASK.

Right.

>
>
>> +	desc |= flags;
>> +	tbl[index] = desc;
>> +}
>> +
>> +static void create_identity_entry(unsigned long *pgtbl_buf,
>> +		unsigned long pgtbl_mem, unsigned long virt,
>> +		unsigned long flags)
>> +{
>> +	unsigned long *tbl = pgtbl_buf;
>> +
>> +	tbl = create_table_entry(pgtbl_buf, pgtbl_mem, tbl, virt,
>> +			PGDIR_SHIFT, PTRS_PER_PGD);
>> +	tbl = create_table_entry(pgtbl_buf, pgtbl_mem, tbl, virt,
>> +			PUD_SHIFT, PTRS_PER_PUD);
>> +	craete_block_entry(tbl, flags, virt, virt);
>
> Nit: create

Ok.

>
>> +}
>> +
>> +/**
>> + * arm64_create_pgtbl_segment - Create page table segments to be used by
>> + * purgatory. Page table will have entries to access memory area of all
>> + * those segments which becomes part of sha verification in purgatory.
>> + * Additionaly, we also create page table for purgatory segment as well.
>
> Nit: additionally,

Ok.

>
>> + */
>> +
>> +static int arm64_create_pgtbl_segment(struct kexec_info *info,
>> +		unsigned long hole_min, unsigned long hole_max)
>> +{
>> +	unsigned long *pgtbl_buf;
>> +	int i;
>> +	unsigned long mstart, mend, pgtbl_mem;
>> +	unsigned long purgatory_base, purgatory_len;
>> +
>> +	pgtbl_buf = xmalloc(MAX_PGTBLE_SZ);
>> +	memset(pgtbl_buf, 0, MAX_PGTBLE_SZ);
>
>> +	pgtbl_mem = add_buffer_phys_virt(info, pgtbl_buf, MAX_PGTBLE_SZ,
>> +			MAX_PGTBLE_SZ, PAGE_SIZE, hole_min, hole_max, 1, 0);
>
> I want to check what this does, but this all looks like it is doing the right thing.
>
>
>> +	for (i = 0; i < info->nr_segments; i++) {
>> +		if (info->segment[i].mem == (void *)info->rhdr.rel_addr) {
>> +			purgatory_base = (unsigned long)info->segment[i].mem;
>> +			purgatory_len = info->segment[i].memsz;
>> +		}
>> +		mstart = (unsigned long)info->segment[i].mem;
>> +		mend = mstart + info->segment[i].memsz;
>> +		mstart &= ~(SECTION_SIZE - 1);
>> +		while (mstart < mend) {
>> +			create_identity_entry(pgtbl_buf, pgtbl_mem,
>> +					mstart, MMU_FLAGS_NORMAL);
>> +			mstart += SECTION_SIZE;
>> +		}
>> +	}
>


~Pratyush

[PATCH V2 1/2] kexec: arm64: create identity page table to be used in purgatory

[Pratyush Anand]

Hi James,

On Wednesday 18 January 2017 01:13 PM, Pratyush Anand wrote:
>
>>
>>> +     * in kexec
>>> +     */
>>> +    if (next_tbl_cnt > 5)
>>> +        die("%s: No more memory for page table\n", __func__);
>>
>> die()? With a bit of juggling can't we return an error so we never try
>> to enable
>> the MMU+dcache instead?
>>
>
> OK. can do that.

It does not seem easy to do that. We will have to revert job of 
add_buffer_phys_virt() in case of failure, and it will need lot of new 
code. So, IMHO it would be better to keep die() as of now.
What do you say?

~Pratyush

[PATCH V2 2/2] arm64: enable d-cache support during purgatory sha verification

[Pratyush Anand]

If a platform supports 4K page table then enable D-cache in purgatory
before SHA verification. Disable it before switching to kernel.

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
 purgatory/arch/arm64/Makefile          |   1 +
 purgatory/arch/arm64/cache.S           | 281 +++++++++++++++++++++++++++++++++
 purgatory/arch/arm64/purgatory-arm64.c |   5 +
 3 files changed, 287 insertions(+)
 create mode 100644 purgatory/arch/arm64/cache.S

diff --git a/purgatory/arch/arm64/Makefile b/purgatory/arch/arm64/Makefile
index 636abeab17b2..db28a0de6891 100644
--- a/purgatory/arch/arm64/Makefile
+++ b/purgatory/arch/arm64/Makefile
@@ -11,6 +11,7 @@ arm64_PURGATORY_EXTRA_CFLAGS = \
 
 arm64_PURGATORY_SRCS += \
 	purgatory/arch/arm64/entry.S \
+	purgatory/arch/arm64/cache.S \
 	purgatory/arch/arm64/purgatory-arm64.c
 
 dist += \
diff --git a/purgatory/arch/arm64/cache.S b/purgatory/arch/arm64/cache.S
new file mode 100644
index 000000000000..48123866ad5f
--- /dev/null
+++ b/purgatory/arch/arm64/cache.S
@@ -0,0 +1,281 @@
+/*
+ * Some of the routines have been copied from Linux Kernel, therefore
+ * copying the license as well.
+ *
+ * Copyright (C) 2001 Deep Blue Solutions Ltd.
+ * Copyright (C) 2012 ARM Ltd.
+ * Copyright (C) 2016 Pratyush Anand <panand@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define SCTLR_ELx_I		(1 << 12)
+#define SCTLR_ELx_C		(1 << 2)
+#define SCTLR_ELx_M		(1 << 0)
+#define SCTLR_ELx_FLAGS 	(SCTLR_ELx_M | SCTLR_ELx_C | SCTLR_ELx_I)
+#define TCR_SHARED_NONE		(0 << 12)
+#define TCR_ORGN_WBWA		(1 << 10)
+#define TCR_IRGN_WBWA		(1 << 8)
+#define TCR_T0SZ_48		16
+#define TCR_TG0_4K		(0 << 14)
+#define TCR_FLAGS 		(TCR_SHARED_NONE | TCR_ORGN_WBWA |\
+				TCR_IRGN_WBWA | TCR_T0SZ_48 | TCR_TG0_4K)
+#define TCR_IPS_EL1_SHIFT	32
+#define TCR_IPS_EL2_SHIFT	16
+#define ID_AA64MMFR0_TGRAN4_SHIFT	28
+#define ID_AA64MMFR0_PARANGE_MASK	0xF
+#define MT_NORMAL		4
+#define MEMORY_ATTRIBUTES	(0xFF << (MT_NORMAL*8))
+
+/*
+ * 	dcache_line_size - get the minimum D-cache line size from the CTR register.
+ */
+	.macro	dcache_line_size, reg, tmp
+	mrs	\tmp, ctr_el0			// read CTR
+	ubfm	\tmp, \tmp, #16, #19		// cache line size encoding
+	mov	\reg, #4			// bytes per word
+	lsl	\reg, \reg, \tmp		// actual cache line size
+	.endm
+
+/*
+ *	flush_dcache_range(start, end)
+ *	- x0 - start	- start address of region
+ *	- x1 - end	- end address of region
+ *
+ */
+flush_dcache_range:
+	dcache_line_size x2, x3
+	sub	x3, x2, #1
+	bic	x0, x0, x3
+1:	dc	civac, x0			// clean & invalidate D line / unified line
+	add	x0, x0, x2
+	cmp	x0, x1
+	b.lo	1b
+	dsb	sy
+	ret
+
+/*
+ *	invalidate_tlbs_el1()
+ */
+invalidate_tlbs_el1:
+	dsb	nshst
+	tlbi	vmalle1
+	dsb	nsh
+	isb
+	ret
+
+/*
+ *	invalidate_tlbs_el2()
+ */
+invalidate_tlbs_el2:
+	dsb	nshst
+	tlbi	alle2
+	dsb	nsh
+	isb
+	ret
+/*
+ *	is_4k_page_not_supported - return nonzero if 4k page is not supported
+ */
+is_4k_page_not_supported:
+	mrs	x0, ID_AA64MMFR0_EL1
+	and	x0, x0, #(0xF << ID_AA64MMFR0_TGRAN4_SHIFT)
+	ret
+
+/*
+ *	get_ips_bits - return supported IPS bits
+ */
+get_ips_bits:
+	mrs	x0, ID_AA64MMFR0_EL1
+	and	x0, x0, #ID_AA64MMFR0_PARANGE_MASK
+	ret
+
+/*
+ * 	get_current_el - Get information about current exception level
+ */
+get_current_el:
+	mrs 	x0, CurrentEL
+	lsr	x0, x0, #2
+	ret
+
+/*
+ * 	invalidate_icache - Invalidate I-cache
+ */
+invalidate_icache:
+	ic	iallu
+	dsb	nsh
+	isb
+	ret
+
+/*
+ * 	set_mair_tcr_ttbr_sctlr_el1(page_table, tcr_flags) - sets MAIR, TCR , TTBR and SCTLR registers
+ * 	x0 - page_table - Page Table Base
+ * 	x1 - tcr_flags - TCR Flags to be set
+ */
+set_mair_tcr_ttbr_sctlr_el1:
+	ldr	x2, =MEMORY_ATTRIBUTES
+	msr	mair_el1, x2
+	msr	tcr_el1, x1
+	msr	ttbr0_el1, x0
+	isb
+	mrs	x0, sctlr_el1
+	ldr	x3, =SCTLR_ELx_FLAGS
+	orr	x0, x0, x3
+	msr	sctlr_el1, x0
+	isb
+	ret
+
+/*
+ * 	set_mair_tcr_ttbr_sctlr_el2(page_table, tcr_flags) - sets MAIR, TCR , TTBR and SCTLR registers
+ * 	x0 - page_table - Page Table Base
+ * 	x1 - tcr_flags - TCR Flags to be set
+ */
+set_mair_tcr_ttbr_sctlr_el2:
+	ldr	x2, =MEMORY_ATTRIBUTES
+	msr	mair_el2, x2
+	msr	tcr_el2, x1
+	msr	ttbr0_el2, x0
+	isb
+	mrs	x0, sctlr_el2
+	ldr	x3, =SCTLR_ELx_FLAGS
+	orr	x0, x0, x3
+	msr	sctlr_el2, x0
+	isb
+	ret
+
+/*
+ * reset_sctlr_el1 - disables cache and mmu
+ */
+reset_sctlr_el1:
+	mrs	x0, sctlr_el1
+	bic	x0, x0, #SCTLR_ELx_C
+	bic	x0, x0, #SCTLR_ELx_M
+	msr	sctlr_el1, x0
+	isb
+	ret
+
+/*
+ * reset_sctlr_el2 - disables cache and mmu
+ */
+reset_sctlr_el2:
+	mrs	x0, sctlr_el2
+	bic	x0, x0, #SCTLR_ELx_C
+	bic	x0, x0, #SCTLR_ELx_M
+	msr	sctlr_el2, x0
+	isb
+	ret
+
+.globl enable_dcache
+/*
+ * x6 - pgtble_base
+ * x7 - tcr_flags
+ * x8 - current_el
+ */
+enable_dcache:
+	stp	x29, x30, [sp,#-16]!
+	stp	x6, x7, [sp,#-16]!
+	stp	x8, x9, [sp,#-16]!
+	bl	is_4k_page_not_supported
+	cmp	x0, #0
+	b.ne	1f
+	ldr	x6, pgtble_base
+	ldr	x7, =TCR_FLAGS
+	bl	get_current_el
+	mov	x8, x0
+	cmp	x8, #2
+	b.ne	2f
+	bl	invalidate_tlbs_el2
+	bl	get_ips_bits
+	lsl	x1, x0, #TCR_IPS_EL2_SHIFT
+	orr	x1, x1, x7
+	mov	x0, x6
+	bl	set_mair_tcr_ttbr_sctlr_el2
+	b	1f
+2:
+	cmp	x8, #1
+	b.ne	1f
+	bl	invalidate_tlbs_el1
+	bl	get_ips_bits
+	lsl	x1, x0, #TCR_IPS_EL1_SHIFT
+	orr	x1, x1, x7
+	mov	x0, x6
+	bl	set_mair_tcr_ttbr_sctlr_el1
+1:
+	ldp	x8, x9, [sp],#16
+	ldp	x6, x7, [sp],#16
+	ldp	x29, x30, [sp],#16
+	ret
+
+.extern sha256_regions
+.globl disable_dcache
+/*
+ * x6 - pgtble_base
+ * x7 - current_el
+ */
+disable_dcache:
+	stp	x29, x30, [sp,#-16]!
+	stp	x6, x7, [sp,#-16]!
+	bl	is_4k_page_not_supported
+	cmp	x0, #0
+	b.ne	1f
+	ldr	x6, pgtble_base
+	bl	get_current_el
+	mov	x7, x0
+	cmp	x7, #2
+	b.ne	2f
+	bl	reset_sctlr_el2
+	b	3f
+2:
+	cmp	x7, #1
+	b.ne	1f
+	bl	reset_sctlr_el1
+3:
+	/*
+	 * we can only branch to function which does not use stack, until
+	 * all memories are flushed.
+	 */
+	bl	invalidate_icache
+	/* flush d cache for purgatory region */
+	ldr	x0, purgatory_base
+	ldr	x1, purgatory_len
+	add	x1, x1, x0
+	bl	flush_dcache_range
+	/* flush d cache for rest of the regions */
+	ldr	x6, =sha256_regions
+4:
+	ldp	x0, x1, [x6],#16
+	cmp	x1, #0
+	b.eq	1f
+	add	x1, x1, x0
+	bl	flush_dcache_range
+	b	4b
+1:
+	ldp	x6, x7, [sp],#16
+	ldp	x29, x30, [sp],#16
+	ret
+
+.align 3
+
+.globl pgtble_base
+pgtble_base:
+	.quad	0
+	.size	pgtble_base, .-pgtble_base
+
+.globl purgatory_base
+purgatory_base:
+	.quad	0
+	.size	purgatory_base, .-purgatory_base
+
+.globl purgatory_len
+purgatory_len:
+	.quad	0
+	.size	purgatory_len, .-purgatory_len
diff --git a/purgatory/arch/arm64/purgatory-arm64.c b/purgatory/arch/arm64/purgatory-arm64.c
index fe50fcf8ebc3..638fb11d9843 100644
--- a/purgatory/arch/arm64/purgatory-arm64.c
+++ b/purgatory/arch/arm64/purgatory-arm64.c
@@ -5,6 +5,9 @@
 #include <stdint.h>
 #include <purgatory.h>
 
+void enable_dcache(void);
+void disable_dcache(void);
+
 void putchar(int ch)
 {
 	/* Nothing for now */
@@ -12,8 +15,10 @@ void putchar(int ch)
 
 void post_verification_setup_arch(void)
 {
+	disable_dcache();
 }
 
 void setup_arch(void)
 {
+	enable_dcache();
 }
-- 
2.7.4

[PATCH V2 0/2] kexec-tools: arm64: Enable D-cache in purgatory

[Pratyush Anand]

Hi James and All,

Any feedback/review comment on it?

~Pratyush

On Monday 19 December 2016 12:43 PM, Pratyush Anand wrote:
> It takes more that 2 minutes to verify SHA in purgatory when vmlinuz image
> is around 13MB and initramfs is around 30MB. It takes more than 20 second
> even when we have -O2 optimization enabled. However, if dcache is enabled
> during purgatory execution then, it takes just a second in SHA
> verification.
>
> Therefore, these patches adds support for dcache enabling facility during
> purgatory execution.
>
> Although I have simplified the logic a bit now, however I understand that
> there are reservations for introducing this complexity for gaining few
> seconding of execution time during kexec or crash reboot.  But, I believe
> if d-cache enabling code is stable enough then there should not be any
> hindrances to accept it. So, please give it a try with your platform and
> let me know if you see any issue or it does not work. I am still open to
> improve it further if needed.
>
> Changes since V1:
> 	- Moved page table creation logic from purgatory to kexec code.
> 	- Only 4K page table is supported, with 48 bit VA and 2M block size
> 	- if platform supports a 4K page size, then D-cache is always
> 	  enabled now.
>
> Pratyush Anand (2):
>   kexec: arm64: create identity page table to be used in purgatory
>   arm64: enable d-cache support during purgatory sha verification
>
>  kexec/arch/arm64/kexec-arm64.c         | 152 ++++++++++++++++++
>  purgatory/arch/arm64/Makefile          |   1 +
>  purgatory/arch/arm64/cache.S           | 281 +++++++++++++++++++++++++++++++++
>  purgatory/arch/arm64/purgatory-arm64.c |   5 +
>  4 files changed, 439 insertions(+)
>  create mode 100644 purgatory/arch/arm64/cache.S
>

[PATCH V2 0/2] kexec-tools: arm64: Enable D-cache in purgatory

[James Morse]

Hi Pratyush,

On 06/01/17 03:31, Pratyush Anand wrote:
> Any feedback/review comment on it?

I started going through this last week, I hope to get back to it later this
week. (I also need to learn/remember how some of the kexec-tools stuff works).


Thanks,

James

[PATCH V2 0/2] kexec-tools: arm64: Enable D-cache in purgatory

[Pratyush Anand]

Hi James and all,

Any review comment for patch 2/2?

If no, then I will address comment for 1/2 and will send v3.

~Pratyush

On Tuesday 10 January 2017 07:41 PM, James Morse wrote:
> Hi Pratyush,
>
> On 06/01/17 03:31, Pratyush Anand wrote:
>> Any feedback/review comment on it?
>
> I started going through this last week, I hope to get back to it later this
> week. (I also need to learn/remember how some of the kexec-tools stuff works).
>
>
> Thanks,
>
> James
>
>