The following is schematic diagram of the program before and after the
modification.
Before:
if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a)
if (memory_limit != PHYS_ADDR_MAX) {} --(b)
if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c)
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)*
After:
if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a)
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)*
if (memory_limit != PHYS_ADDR_MAX) {} --(b)
if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c)
After grouping modification of memstart_address by moving linear region
randomization ahead of memory_init, driver can safely using macro,
__phys_to_virt, in (b) or (c), if necessary.
Signed-off-by: pierre Kuo <[email protected]>
---
Changes in v2:
- add Fixes tag
Changes in v3:
- adding patch of shifting linear region randomization ahead of
memory_limit
arch/arm64/mm/init.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 7205a9085b4d..5142020fc146 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -389,6 +389,23 @@ void __init arm64_memblock_init(void)
memblock_remove(0, memstart_addr);
}
+ if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+ extern u16 memstart_offset_seed;
+ u64 range = linear_region_size -
+ (memblock_end_of_DRAM() - memblock_start_of_DRAM());
+
+ /*
+ * If the size of the linear region exceeds, by a sufficient
+ * margin, the size of the region that the available physical
+ * memory spans, randomize the linear region as well.
+ */
+ if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
+ range /= ARM64_MEMSTART_ALIGN;
+ memstart_addr -= ARM64_MEMSTART_ALIGN *
+ ((range * memstart_offset_seed) >> 16);
+ }
+ }
+
/*
* Apply the memory limit if it was set. Since the kernel may be loaded
* high up in memory, add back the kernel region that must be accessible
@@ -428,22 +445,6 @@ void __init arm64_memblock_init(void)
}
}
- if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
- extern u16 memstart_offset_seed;
- u64 range = linear_region_size -
- (memblock_end_of_DRAM() - memblock_start_of_DRAM());
-
- /*
- * If the size of the linear region exceeds, by a sufficient
- * margin, the size of the region that the available physical
- * memory spans, randomize the linear region as well.
- */
- if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
- range /= ARM64_MEMSTART_ALIGN;
- memstart_addr -= ARM64_MEMSTART_ALIGN *
- ((range * memstart_offset_seed) >> 16);
- }
- }
/*
* Register the kernel text, kernel data, initrd, and initial
--
2.17.1
in the previous case, initrd_start and initrd_end can be successfully
returned either (base < memblock_start_of_DRAM()) or (base + size >
memblock_start_of_DRAM() + linear_region_size).
That means even linear mapping range check fail for initrd_start and
initrd_end, it still can get virtual address. Here we put
initrd_start/initrd_end to be calculated only when linear mapping check
pass.
Fixes: c756c592e442 ("arm64: Utilize phys_initrd_start/phys_initrd_size")
Reviewed-by: Steven Price <[email protected]>
Signed-off-by: pierre Kuo <[email protected]>
---
Changes in v2:
- add Fixes tag
Changes in v3:
- adding patch of shifting linear region randomization ahead of
memory_limit
arch/arm64/mm/init.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 5142020fc146..566761da5719 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -442,6 +442,9 @@ void __init arm64_memblock_init(void)
memblock_remove(base, size); /* clear MEMBLOCK_ flags */
memblock_add(base, size);
memblock_reserve(base, size);
+ /* the generic initrd code expects virtual addresses */
+ initrd_start = __phys_to_virt(phys_initrd_start);
+ initrd_end = initrd_start + phys_initrd_size;
}
}
@@ -451,11 +454,6 @@ void __init arm64_memblock_init(void)
* pagetables with memblock.
*/
memblock_reserve(__pa_symbol(_text), _end - _text);
- if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
- /* the generic initrd code expects virtual addresses */
- initrd_start = __phys_to_virt(phys_initrd_start);
- initrd_end = initrd_start + phys_initrd_size;
- }
early_init_fdt_scan_reserved_mem();
--
2.17.1
hi will and all:
>
> The following is schematic diagram of the program before and after the
> modification.
>
> Before:
> if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a)
> if (memory_limit != PHYS_ADDR_MAX) {} --(b)
> if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c)
> if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)*
>
> After:
> if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a)
> if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)*
> if (memory_limit != PHYS_ADDR_MAX) {} --(b)
> if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c)
>
> After grouping modification of memstart_address by moving linear region
> randomization ahead of memory_init, driver can safely using macro,
> __phys_to_virt, in (b) or (c), if necessary.
>
> Signed-off-by: pierre Kuo <[email protected]>
> ---
> Changes in v2:
> - add Fixes tag
>
> Changes in v3:
> - adding patch of shifting linear region randomization ahead of
> memory_limit
>
> arch/arm64/mm/init.c | 33 +++++++++++++++++----------------
> 1 file changed, 17 insertions(+), 16 deletions(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 7205a9085b4d..5142020fc146 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -389,6 +389,23 @@ void __init arm64_memblock_init(void)
> memblock_remove(0, memstart_addr);
> }
>
> + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
> + extern u16 memstart_offset_seed;
> + u64 range = linear_region_size -
> + (memblock_end_of_DRAM() - memblock_start_of_DRAM());
> +
> + /*
> + * If the size of the linear region exceeds, by a sufficient
> + * margin, the size of the region that the available physical
> + * memory spans, randomize the linear region as well.
> + */
> + if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
> + range /= ARM64_MEMSTART_ALIGN;
> + memstart_addr -= ARM64_MEMSTART_ALIGN *
> + ((range * memstart_offset_seed) >> 16);
> + }
> + }
> +
> /*
> * Apply the memory limit if it was set. Since the kernel may be loaded
> * high up in memory, add back the kernel region that must be accessible
> @@ -428,22 +445,6 @@ void __init arm64_memblock_init(void)
> }
> }
>
> - if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
> - extern u16 memstart_offset_seed;
> - u64 range = linear_region_size -
> - (memblock_end_of_DRAM() - memblock_start_of_DRAM());
> -
> - /*
> - * If the size of the linear region exceeds, by a sufficient
> - * margin, the size of the region that the available physical
> - * memory spans, randomize the linear region as well.
> - */
> - if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
> - range /= ARM64_MEMSTART_ALIGN;
> - memstart_addr -= ARM64_MEMSTART_ALIGN *
> - ((range * memstart_offset_seed) >> 16);
> - }
> - }
>
> /*
> * Register the kernel text, kernel data, initrd, and initial
Would you mind to give some comment and suggestion for these v3 patches?
https://lkml.org/lkml/2019/4/8/682
https://lkml.org/lkml/2019/4/8/683
Sincerely appreciate your kind help,
On Mon, 8 Apr 2019 at 18:33, pierre Kuo <[email protected]> wrote:
>
> The following is schematic diagram of the program before and after the
> modification.
>
> Before:
> if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a)
> if (memory_limit != PHYS_ADDR_MAX) {} --(b)
> if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c)
> if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)*
>
> After:
> if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a)
> if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)*
> if (memory_limit != PHYS_ADDR_MAX) {} --(b)
> if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c)
>
> After grouping modification of memstart_address by moving linear region
> randomization ahead of memory_init, driver can safely using macro,
> __phys_to_virt, in (b) or (c), if necessary.
>
Why is this an advantage?
> Signed-off-by: pierre Kuo <[email protected]>
> ---
> Changes in v2:
> - add Fixes tag
>
> Changes in v3:
> - adding patch of shifting linear region randomization ahead of
> memory_limit
>
> arch/arm64/mm/init.c | 33 +++++++++++++++++----------------
> 1 file changed, 17 insertions(+), 16 deletions(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 7205a9085b4d..5142020fc146 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -389,6 +389,23 @@ void __init arm64_memblock_init(void)
> memblock_remove(0, memstart_addr);
> }
>
> + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
> + extern u16 memstart_offset_seed;
> + u64 range = linear_region_size -
> + (memblock_end_of_DRAM() - memblock_start_of_DRAM());
> +
> + /*
> + * If the size of the linear region exceeds, by a sufficient
> + * margin, the size of the region that the available physical
> + * memory spans, randomize the linear region as well.
> + */
> + if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
> + range /= ARM64_MEMSTART_ALIGN;
> + memstart_addr -= ARM64_MEMSTART_ALIGN *
> + ((range * memstart_offset_seed) >> 16);
> + }
> + }
> +
> /*
> * Apply the memory limit if it was set. Since the kernel may be loaded
> * high up in memory, add back the kernel region that must be accessible
> @@ -428,22 +445,6 @@ void __init arm64_memblock_init(void)
> }
> }
>
> - if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
> - extern u16 memstart_offset_seed;
> - u64 range = linear_region_size -
> - (memblock_end_of_DRAM() - memblock_start_of_DRAM());
> -
> - /*
> - * If the size of the linear region exceeds, by a sufficient
> - * margin, the size of the region that the available physical
> - * memory spans, randomize the linear region as well.
> - */
> - if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
> - range /= ARM64_MEMSTART_ALIGN;
> - memstart_addr -= ARM64_MEMSTART_ALIGN *
> - ((range * memstart_offset_seed) >> 16);
> - }
> - }
>
> /*
> * Register the kernel text, kernel data, initrd, and initial
> --
> 2.17.1
>
hi Ard:
> > The following is schematic diagram of the program before and after the
> > modification.
> >
> > Before:
> > if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a)
> > if (memory_limit != PHYS_ADDR_MAX) {} --(b)
> > if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c)
> > if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)*
> >
> > After:
> > if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a)
> > if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)*
> > if (memory_limit != PHYS_ADDR_MAX) {} --(b)
> > if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c)
> >
> > After grouping modification of memstart_address by moving linear region
> > randomization ahead of memory_init, driver can safely using macro,
> > __phys_to_virt, in (b) or (c), if necessary.
> >
>
> Why is this an advantage?
1st, by putting (d) right behind (a), driver can safely uses macro,
__phys_to_virt that depends on memstart_address, in (b) and (c) if necessary.
That means:
(a)
(d)
----- finish modification of memstart_address --------
(b) --> can safely use __phys_to_virt
(c) --> can safely use __phys_to_virt
2nd, it can make current driver more concise.
Letting (d) right behind (a), as below v3 patch shows,
https://lkml.org/lkml/2019/4/8/683
it can put initrd_start/initrd_end to be calculated only when linear
mapping check
pass and concise the driver by eliminating
"if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) " as patch shows.
Thanks for your message.