Re: [PATCH v3 3/5] arm64/mm: Create initial page tables in init_pg_dir
Hi James,
On Fri, Jul 06, 2018 at 03:41:07PM +0100, James Morse wrote:
> I missed one: head.S has a call to kasan_early_init() before start_kernel(),
> this goes messing with the page tables, and calls pgd_offset_k(), which pulls
> in
> swapper_pg_dir. This one is enabled by CONFIG_KASAN.
>
> Something like that same hunk [0] in kasan_early_init() fixes it. This is
> still
> within arch/arm64, so I still think we should get away without some #ifdeffery
> to override the core-code's initial setup of swapper_pg_dir...
I'm sorry to reply you so late, I missed this email before.
In order to ensure that pgd_offset_k() works properly, I update
init_mm.pgd by introducing set_init_mm_pgd(). And its implementation is
like this:
>diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>index 65f86271f02b..e4f0868b4cfd 100644
>--- a/arch/arm64/mm/mmu.c
>+++ b/arch/arm64/mm/mmu.c
>@@ -623,6 +623,19 @@ static void __init map_kernel(pgd_t *pgdp)
>kasan_copy_shadow(pgdp);
> }
>
>+void __init set_init_mm_pgd(pgd_t *pgd)
>+{
>+ pgd_t **addr = &(init_mm.pgd);
>+
>+ asm volatile("str %x0, [%1]\n"
>+ : : "r" (pgd), "r" (addr) : "memory");
>+}
> /*
> * paging_init() sets up the page tables, initialises the zone memory
> * maps and sets up the zero page.
The purpose of using assembly is to prevent KASAN instrumentation, as
KASAN has not been initialized when this function is called:
>diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
>index c3e4b1886cde..ede2e964592b 100644
>--- a/arch/arm64/kernel/head.S
>+++ b/arch/arm64/kernel/head.S
>@@ -439,6 +438,9 @@ __primary_switched:
>bl __pi_memset
>dsb ishst // Make zero page visible to
> PTW
>
>+ adrpx0, init_pg_dir
>+ bl set_init_mm_pgd
>+
> #ifdef CONFIG_KASAN
>bl kasan_early_init
> #endif
What do you think?
Re: [PATCH v3 3/5] arm64/mm: Create initial page tables in init_pg_dir
Hi James,
On Fri, Jul 06, 2018 at 03:41:07PM +0100, James Morse wrote:
> I missed one: head.S has a call to kasan_early_init() before start_kernel(),
> this goes messing with the page tables, and calls pgd_offset_k(), which pulls
> in
> swapper_pg_dir. This one is enabled by CONFIG_KASAN.
>
> Something like that same hunk [0] in kasan_early_init() fixes it. This is
> still
> within arch/arm64, so I still think we should get away without some #ifdeffery
> to override the core-code's initial setup of swapper_pg_dir...
I'm sorry to reply you so late, I missed this email before.
In order to ensure that pgd_offset_k() works properly, I update
init_mm.pgd by introducing set_init_mm_pgd(). And its implementation is
like this:
>diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>index 65f86271f02b..e4f0868b4cfd 100644
>--- a/arch/arm64/mm/mmu.c
>+++ b/arch/arm64/mm/mmu.c
>@@ -623,6 +623,19 @@ static void __init map_kernel(pgd_t *pgdp)
>kasan_copy_shadow(pgdp);
> }
>
>+void __init set_init_mm_pgd(pgd_t *pgd)
>+{
>+ pgd_t **addr = &(init_mm.pgd);
>+
>+ asm volatile("str %x0, [%1]\n"
>+ : : "r" (pgd), "r" (addr) : "memory");
>+}
> /*
> * paging_init() sets up the page tables, initialises the zone memory
> * maps and sets up the zero page.
The purpose of using assembly is to prevent KASAN instrumentation, as
KASAN has not been initialized when this function is called:
>diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
>index c3e4b1886cde..ede2e964592b 100644
>--- a/arch/arm64/kernel/head.S
>+++ b/arch/arm64/kernel/head.S
>@@ -439,6 +438,9 @@ __primary_switched:
>bl __pi_memset
>dsb ishst // Make zero page visible to
> PTW
>
>+ adrpx0, init_pg_dir
>+ bl set_init_mm_pgd
>+
> #ifdef CONFIG_KASAN
>bl kasan_early_init
> #endif
What do you think?
Re: [PATCH v3 3/5] arm64/mm: Create initial page tables in init_pg_dir
Hi Jun, On 06/07/18 09:58, James Morse wrote: > The series so far fails to boot from me. This is because the kaslr code tries > to > read the kaslr-seed from the DT, via the fixmap. To do this, it needs the > fixmap > tables installed, which early_fixmap_init() does. > > early_fixmap_init() calls pgd_offset_k(), which assumes init_mm.pgd is in use, > so we hit a BUG_ON() when trying to setup the fixmap because we added the > tables > to the wrong page tables. > > If you enable 'CONFIG_RANDOMIZE_BASE', even without EFI you should see the > same > thing happen. > > > I think we should move this hunk: >> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c >> index 30ad2f085d1f..b065c08d4008 100644 >> --- a/arch/arm64/kernel/setup.c >> +++ b/arch/arm64/kernel/setup.c >> @@ -249,6 +249,7 @@ void __init setup_arch(char **cmdline_p) >> init_mm.end_code = (unsigned long) _etext; >> init_mm.end_data = (unsigned long) _edata; >> init_mm.brk= (unsigned long) _end; >> +init_mm.pgd= init_pg_dir; >> >> *cmdline_p = boot_command_line; >> > > into early_fixmap_init(), which is the first thing setup_arch() calls. > Something like [0] fixes it. > > This looks to be the only thing that goes near init_mm.pgd before > paging_init(). I missed one: head.S has a call to kasan_early_init() before start_kernel(), this goes messing with the page tables, and calls pgd_offset_k(), which pulls in swapper_pg_dir. This one is enabled by CONFIG_KASAN. Something like that same hunk [0] in kasan_early_init() fixes it. This is still within arch/arm64, so I still think we should get away without some #ifdeffery to override the core-code's initial setup of swapper_pg_dir... Thanks, James > [0] make sure fixmap tables go in the init page tables > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 117d080639b3..e097c78a66f8 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -770,6 +771,13 @@ void __init early_fixmap_init(void) > pmd_t *pmdp; > unsigned long addr = FIXADDR_START; > > + /* > +* During early setup we use init_pg_dir, update init_mm so its > +* implicit use by pgd_offset_k() gets the live page tables. > +* swapper_pg_dir is restored by paging_init(). > +*/ > + init_mm.pgd = init_pg_dir; > + > pgdp = pgd_offset_k(addr); > pgd = READ_ONCE(*pgdp); > if (CONFIG_PGTABLE_LEVELS > 3 && > > >
Re: [PATCH v3 3/5] arm64/mm: Create initial page tables in init_pg_dir
Hi Jun, On 06/07/18 09:58, James Morse wrote: > The series so far fails to boot from me. This is because the kaslr code tries > to > read the kaslr-seed from the DT, via the fixmap. To do this, it needs the > fixmap > tables installed, which early_fixmap_init() does. > > early_fixmap_init() calls pgd_offset_k(), which assumes init_mm.pgd is in use, > so we hit a BUG_ON() when trying to setup the fixmap because we added the > tables > to the wrong page tables. > > If you enable 'CONFIG_RANDOMIZE_BASE', even without EFI you should see the > same > thing happen. > > > I think we should move this hunk: >> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c >> index 30ad2f085d1f..b065c08d4008 100644 >> --- a/arch/arm64/kernel/setup.c >> +++ b/arch/arm64/kernel/setup.c >> @@ -249,6 +249,7 @@ void __init setup_arch(char **cmdline_p) >> init_mm.end_code = (unsigned long) _etext; >> init_mm.end_data = (unsigned long) _edata; >> init_mm.brk= (unsigned long) _end; >> +init_mm.pgd= init_pg_dir; >> >> *cmdline_p = boot_command_line; >> > > into early_fixmap_init(), which is the first thing setup_arch() calls. > Something like [0] fixes it. > > This looks to be the only thing that goes near init_mm.pgd before > paging_init(). I missed one: head.S has a call to kasan_early_init() before start_kernel(), this goes messing with the page tables, and calls pgd_offset_k(), which pulls in swapper_pg_dir. This one is enabled by CONFIG_KASAN. Something like that same hunk [0] in kasan_early_init() fixes it. This is still within arch/arm64, so I still think we should get away without some #ifdeffery to override the core-code's initial setup of swapper_pg_dir... Thanks, James > [0] make sure fixmap tables go in the init page tables > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 117d080639b3..e097c78a66f8 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -770,6 +771,13 @@ void __init early_fixmap_init(void) > pmd_t *pmdp; > unsigned long addr = FIXADDR_START; > > + /* > +* During early setup we use init_pg_dir, update init_mm so its > +* implicit use by pgd_offset_k() gets the live page tables. > +* swapper_pg_dir is restored by paging_init(). > +*/ > + init_mm.pgd = init_pg_dir; > + > pgdp = pgd_offset_k(addr); > pgd = READ_ONCE(*pgdp); > if (CONFIG_PGTABLE_LEVELS > 3 && > > >
Re: [PATCH v3 3/5] arm64/mm: Create initial page tables in init_pg_dir
Hi Jun,
On 02/07/18 12:16, Jun Yao wrote:
> Create initial page tables in init_pg_dir and then create final
> page tables in swapper_pg_dir directly.
This is what the patch does, but doesn't preserve the why for the git-log. Could
you expand it to describe why we're doing this.
The series so far fails to boot from me. This is because the kaslr code tries to
read the kaslr-seed from the DT, via the fixmap. To do this, it needs the fixmap
tables installed, which early_fixmap_init() does.
early_fixmap_init() calls pgd_offset_k(), which assumes init_mm.pgd is in use,
so we hit a BUG_ON() when trying to setup the fixmap because we added the tables
to the wrong page tables.
If you enable 'CONFIG_RANDOMIZE_BASE', even without EFI you should see the same
thing happen.
I think we should move this hunk:
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 30ad2f085d1f..b065c08d4008 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -249,6 +249,7 @@ void __init setup_arch(char **cmdline_p)
> init_mm.end_code = (unsigned long) _etext;
> init_mm.end_data = (unsigned long) _edata;
> init_mm.brk= (unsigned long) _end;
> + init_mm.pgd= init_pg_dir;
>
> *cmdline_p = boot_command_line;
>
into early_fixmap_init(), which is the first thing setup_arch() calls.
Something like [0] fixes it.
This looks to be the only thing that goes near init_mm.pgd before paging_init().
> diff --git a/arch/arm64/include/asm/pgtable.h
> b/arch/arm64/include/asm/pgtable.h
> index 7c4c8f318ba9..3b408f21fe2e 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -718,6 +718,8 @@ static inline pmd_t pmdp_establish(struct vm_area_struct
> *vma,
> }
> #endif
>
> +extern pgd_t init_pg_dir[PTRS_PER_PGD] __section(.init.data);
> +extern pgd_t init_pg_end[] __section(.init.data);
normally we'd spell this '__initdata', but if we move them out of the
'.init.data' section we shouldn't, otherwise the extern definition doesn't match
where the symbol appears. (Looks like I was wrong to think that tools like
sparse pick this up, that's just the __iomem/__user stuff.)
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 2dbb2c9f1ec1..a7ab0010ff80 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -628,26 +628,10 @@ static void __init map_kernel(pgd_t *pgdp)
> */
> void __init paging_init(void)
> {
> - phys_addr_t pgd_phys = early_pgtable_alloc();
> - pgd_t *pgdp = pgd_set_fixmap(pgd_phys);
> -
> - map_kernel(pgdp);
> - map_mem(pgdp);
> -
> - /*
> - * We want to reuse the original swapper_pg_dir so we don't have to
> - * communicate the new address to non-coherent secondaries in
> - * secondary_entry, and so cpu_switch_mm can generate the address with
> - * adrp+add rather than a load from some global variable.
> - *
> - * To do this we need to go via a temporary pgd.
> - */
> - cpu_replace_ttbr1(__va(pgd_phys));
> - memcpy(swapper_pg_dir, pgdp, PGD_SIZE);
> - cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
> -
> - pgd_clear_fixmap();
> - memblock_free(pgd_phys, PAGE_SIZE);
> + map_kernel(swapper_pg_dir);
> + map_mem(swapper_pg_dir);
> + cpu_replace_ttbr1(swapper_pg_dir);
The lm_alias() here is important: cpu_replace_ttbr1() calls virt_to_phys() on
its argument, virt_to_phys() is only intended for addresses in the linear-map
region of the VA space, as it works by doing some arithmetic with the address.
swapper_pg_dir is the name of the kernel symbol, so its address will be in the
kernel-text region of the VA space.
Today virt_to_phys() catches this happening and fixes it, CONFIG_DEBUG_VIRTUAL
will give you a warning, at some point virt_to_phys()'s safety net will go-away.
The original call that did this was wrapped in lm_alias(), which gives you the
linear-map address of a symbol in the kernel-text.
Thanks,
James
[0] make sure fixmap tables go in the init page tables
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 117d080639b3..e097c78a66f8 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -770,6 +771,13 @@ void __init early_fixmap_init(void)
pmd_t *pmdp;
unsigned long addr = FIXADDR_START;
+ /*
+* During early setup we use init_pg_dir, update init_mm so its
+* implicit use by pgd_offset_k() gets the live page tables.
+* swapper_pg_dir is restored by paging_init().
+*/
+ init_mm.pgd = init_pg_dir;
+
pgdp = pgd_offset_k(addr);
pgd = READ_ONCE(*pgdp);
if (CONFIG_PGTABLE_LEVELS > 3 &&
Re: [PATCH v3 3/5] arm64/mm: Create initial page tables in init_pg_dir
Hi Jun,
On 02/07/18 12:16, Jun Yao wrote:
> Create initial page tables in init_pg_dir and then create final
> page tables in swapper_pg_dir directly.
This is what the patch does, but doesn't preserve the why for the git-log. Could
you expand it to describe why we're doing this.
The series so far fails to boot from me. This is because the kaslr code tries to
read the kaslr-seed from the DT, via the fixmap. To do this, it needs the fixmap
tables installed, which early_fixmap_init() does.
early_fixmap_init() calls pgd_offset_k(), which assumes init_mm.pgd is in use,
so we hit a BUG_ON() when trying to setup the fixmap because we added the tables
to the wrong page tables.
If you enable 'CONFIG_RANDOMIZE_BASE', even without EFI you should see the same
thing happen.
I think we should move this hunk:
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 30ad2f085d1f..b065c08d4008 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -249,6 +249,7 @@ void __init setup_arch(char **cmdline_p)
> init_mm.end_code = (unsigned long) _etext;
> init_mm.end_data = (unsigned long) _edata;
> init_mm.brk= (unsigned long) _end;
> + init_mm.pgd= init_pg_dir;
>
> *cmdline_p = boot_command_line;
>
into early_fixmap_init(), which is the first thing setup_arch() calls.
Something like [0] fixes it.
This looks to be the only thing that goes near init_mm.pgd before paging_init().
> diff --git a/arch/arm64/include/asm/pgtable.h
> b/arch/arm64/include/asm/pgtable.h
> index 7c4c8f318ba9..3b408f21fe2e 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -718,6 +718,8 @@ static inline pmd_t pmdp_establish(struct vm_area_struct
> *vma,
> }
> #endif
>
> +extern pgd_t init_pg_dir[PTRS_PER_PGD] __section(.init.data);
> +extern pgd_t init_pg_end[] __section(.init.data);
normally we'd spell this '__initdata', but if we move them out of the
'.init.data' section we shouldn't, otherwise the extern definition doesn't match
where the symbol appears. (Looks like I was wrong to think that tools like
sparse pick this up, that's just the __iomem/__user stuff.)
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 2dbb2c9f1ec1..a7ab0010ff80 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -628,26 +628,10 @@ static void __init map_kernel(pgd_t *pgdp)
> */
> void __init paging_init(void)
> {
> - phys_addr_t pgd_phys = early_pgtable_alloc();
> - pgd_t *pgdp = pgd_set_fixmap(pgd_phys);
> -
> - map_kernel(pgdp);
> - map_mem(pgdp);
> -
> - /*
> - * We want to reuse the original swapper_pg_dir so we don't have to
> - * communicate the new address to non-coherent secondaries in
> - * secondary_entry, and so cpu_switch_mm can generate the address with
> - * adrp+add rather than a load from some global variable.
> - *
> - * To do this we need to go via a temporary pgd.
> - */
> - cpu_replace_ttbr1(__va(pgd_phys));
> - memcpy(swapper_pg_dir, pgdp, PGD_SIZE);
> - cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
> -
> - pgd_clear_fixmap();
> - memblock_free(pgd_phys, PAGE_SIZE);
> + map_kernel(swapper_pg_dir);
> + map_mem(swapper_pg_dir);
> + cpu_replace_ttbr1(swapper_pg_dir);
The lm_alias() here is important: cpu_replace_ttbr1() calls virt_to_phys() on
its argument, virt_to_phys() is only intended for addresses in the linear-map
region of the VA space, as it works by doing some arithmetic with the address.
swapper_pg_dir is the name of the kernel symbol, so its address will be in the
kernel-text region of the VA space.
Today virt_to_phys() catches this happening and fixes it, CONFIG_DEBUG_VIRTUAL
will give you a warning, at some point virt_to_phys()'s safety net will go-away.
The original call that did this was wrapped in lm_alias(), which gives you the
linear-map address of a symbol in the kernel-text.
Thanks,
James
[0] make sure fixmap tables go in the init page tables
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 117d080639b3..e097c78a66f8 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -770,6 +771,13 @@ void __init early_fixmap_init(void)
pmd_t *pmdp;
unsigned long addr = FIXADDR_START;
+ /*
+* During early setup we use init_pg_dir, update init_mm so its
+* implicit use by pgd_offset_k() gets the live page tables.
+* swapper_pg_dir is restored by paging_init().
+*/
+ init_mm.pgd = init_pg_dir;
+
pgdp = pgd_offset_k(addr);
pgd = READ_ONCE(*pgdp);
if (CONFIG_PGTABLE_LEVELS > 3 &&
[PATCH v3 3/5] arm64/mm: Create initial page tables in init_pg_dir
Create initial page tables in init_pg_dir and then create final
page tables in swapper_pg_dir directly.
Signed-off-by: Jun Yao
---
arch/arm64/include/asm/pgtable.h | 2 ++
arch/arm64/kernel/head.S | 4 ++--
arch/arm64/kernel/setup.c| 1 +
arch/arm64/mm/mmu.c | 24
4 files changed, 9 insertions(+), 22 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7c4c8f318ba9..3b408f21fe2e 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -718,6 +718,8 @@ static inline pmd_t pmdp_establish(struct vm_area_struct
*vma,
}
#endif
+extern pgd_t init_pg_dir[PTRS_PER_PGD] __section(.init.data);
+extern pgd_t init_pg_end[] __section(.init.data);
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
extern pgd_t swapper_pg_end[];
extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index a1c7a4d3b9f3..a8e9432ffa8a 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -380,7 +380,7 @@ __create_page_tables:
/*
* Map the kernel image (starting with PHYS_OFFSET).
*/
- adrpx0, swapper_pg_dir
+ adrpx0, init_pg_dir
mov_q x5, KIMAGE_VADDR + TEXT_OFFSET // compile time __va(_text)
add x5, x5, x23 // add KASLR displacement
mov x4, PTRS_PER_PGD
@@ -837,7 +837,7 @@ __primary_switch:
mrs x20, sctlr_el1 // preserve old SCTLR_EL1 value
#endif
- adrpx26, swapper_pg_dir
+ adrpx26, init_pg_dir
bl __enable_mmu
#ifdef CONFIG_RELOCATABLE
bl __relocate_kernel
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 30ad2f085d1f..b065c08d4008 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -249,6 +249,7 @@ void __init setup_arch(char **cmdline_p)
init_mm.end_code = (unsigned long) _etext;
init_mm.end_data = (unsigned long) _edata;
init_mm.brk= (unsigned long) _end;
+ init_mm.pgd= init_pg_dir;
*cmdline_p = boot_command_line;
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 2dbb2c9f1ec1..a7ab0010ff80 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -628,26 +628,10 @@ static void __init map_kernel(pgd_t *pgdp)
*/
void __init paging_init(void)
{
- phys_addr_t pgd_phys = early_pgtable_alloc();
- pgd_t *pgdp = pgd_set_fixmap(pgd_phys);
-
- map_kernel(pgdp);
- map_mem(pgdp);
-
- /*
-* We want to reuse the original swapper_pg_dir so we don't have to
-* communicate the new address to non-coherent secondaries in
-* secondary_entry, and so cpu_switch_mm can generate the address with
-* adrp+add rather than a load from some global variable.
-*
-* To do this we need to go via a temporary pgd.
-*/
- cpu_replace_ttbr1(__va(pgd_phys));
- memcpy(swapper_pg_dir, pgdp, PGD_SIZE);
- cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
-
- pgd_clear_fixmap();
- memblock_free(pgd_phys, PAGE_SIZE);
+ map_kernel(swapper_pg_dir);
+ map_mem(swapper_pg_dir);
+ cpu_replace_ttbr1(swapper_pg_dir);
+ init_mm.pgd = swapper_pg_dir;
/*
* We only reuse the PGD from the swapper_pg_dir, not the pud + pmd
--
2.17.1
[PATCH v3 3/5] arm64/mm: Create initial page tables in init_pg_dir
Create initial page tables in init_pg_dir and then create final
page tables in swapper_pg_dir directly.
Signed-off-by: Jun Yao
---
arch/arm64/include/asm/pgtable.h | 2 ++
arch/arm64/kernel/head.S | 4 ++--
arch/arm64/kernel/setup.c| 1 +
arch/arm64/mm/mmu.c | 24
4 files changed, 9 insertions(+), 22 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7c4c8f318ba9..3b408f21fe2e 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -718,6 +718,8 @@ static inline pmd_t pmdp_establish(struct vm_area_struct
*vma,
}
#endif
+extern pgd_t init_pg_dir[PTRS_PER_PGD] __section(.init.data);
+extern pgd_t init_pg_end[] __section(.init.data);
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
extern pgd_t swapper_pg_end[];
extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index a1c7a4d3b9f3..a8e9432ffa8a 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -380,7 +380,7 @@ __create_page_tables:
/*
* Map the kernel image (starting with PHYS_OFFSET).
*/
- adrpx0, swapper_pg_dir
+ adrpx0, init_pg_dir
mov_q x5, KIMAGE_VADDR + TEXT_OFFSET // compile time __va(_text)
add x5, x5, x23 // add KASLR displacement
mov x4, PTRS_PER_PGD
@@ -837,7 +837,7 @@ __primary_switch:
mrs x20, sctlr_el1 // preserve old SCTLR_EL1 value
#endif
- adrpx26, swapper_pg_dir
+ adrpx26, init_pg_dir
bl __enable_mmu
#ifdef CONFIG_RELOCATABLE
bl __relocate_kernel
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 30ad2f085d1f..b065c08d4008 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -249,6 +249,7 @@ void __init setup_arch(char **cmdline_p)
init_mm.end_code = (unsigned long) _etext;
init_mm.end_data = (unsigned long) _edata;
init_mm.brk= (unsigned long) _end;
+ init_mm.pgd= init_pg_dir;
*cmdline_p = boot_command_line;
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 2dbb2c9f1ec1..a7ab0010ff80 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -628,26 +628,10 @@ static void __init map_kernel(pgd_t *pgdp)
*/
void __init paging_init(void)
{
- phys_addr_t pgd_phys = early_pgtable_alloc();
- pgd_t *pgdp = pgd_set_fixmap(pgd_phys);
-
- map_kernel(pgdp);
- map_mem(pgdp);
-
- /*
-* We want to reuse the original swapper_pg_dir so we don't have to
-* communicate the new address to non-coherent secondaries in
-* secondary_entry, and so cpu_switch_mm can generate the address with
-* adrp+add rather than a load from some global variable.
-*
-* To do this we need to go via a temporary pgd.
-*/
- cpu_replace_ttbr1(__va(pgd_phys));
- memcpy(swapper_pg_dir, pgdp, PGD_SIZE);
- cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
-
- pgd_clear_fixmap();
- memblock_free(pgd_phys, PAGE_SIZE);
+ map_kernel(swapper_pg_dir);
+ map_mem(swapper_pg_dir);
+ cpu_replace_ttbr1(swapper_pg_dir);
+ init_mm.pgd = swapper_pg_dir;
/*
* We only reuse the PGD from the swapper_pg_dir, not the pud + pmd
--
2.17.1
