Cannot load linux after recent efi-related changes

Cannot load linux after recent efi-related changes

[Mike Krinkin]

Hello,

after commit 3dad6f7f6975 ("x86/efi: Defer efi_esrt_init until after
memblock_x86_fill") kernel hits BUG_ON __efi_enter_virtual_mode because
efi.systab is NULL. With older kernel versions i face the problem with
efi_mem_reserve described in the commit.

AFAICS, get_systab_virt_addr called from efi_map_regions should set
efi.systab, but i dumped memory desciptors in efi_map_regions and
apparently none of them describes region that contains efi_phys.systab,
so efi.systab remains unset.

Re: Cannot load linux after recent efi-related changes

[Mike Krinkin]

On Sat, Sep 17, 2016 at 07:23:57PM +0300, Mike Krinkin wrote:
> Hello,
> 
> after commit 3dad6f7f6975 ("x86/efi: Defer efi_esrt_init until after
> memblock_x86_fill") kernel hits BUG_ON __efi_enter_virtual_mode because
> efi.systab is NULL. With older kernel versions i face the problem with
> efi_mem_reserve described in the commit.
> 
> AFAICS, get_systab_virt_addr called from efi_map_regions should set
> efi.systab, but i dumped memory desciptors in efi_map_regions and
> apparently none of them describes region that contains efi_phys.systab,
> so efi.systab remains unset.

I investigated it a bit further, and apparently problem occurs because
efi_esrt_init calls efi_mem_reserve with unaligned range boundaries, and
efi_memmap_insert doesn't handle unaligned ranges properly. The following
fix solves problem for me:

>From 23f7134a6dd3a3c47f875395933a68e1a83d0f0e Mon Sep 17 00:00:00 2001
From: Mike Krinkin <krinkin.m.u-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Date: Sun, 18 Sep 2016 03:53:52 +0300
Subject: [PATCH] efi: force page alignment in efi_mem_insert

efi_mem_insert might be called with unaligned range boundaries,
for example, for me it happens because esrt size is not page
aligned, that, in turn, results in wrong memory map and triggers
BUG_ON in __efi_enter_virtual_mode.

Force page alignment on memory range boundaries in efi_mem_insert.

Signed-off-by: Mike Krinkin <krinkin.m.u-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/firmware/efi/memmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
index cd96086..34322d1 100644
--- a/drivers/firmware/efi/memmap.c
+++ b/drivers/firmware/efi/memmap.c
@@ -221,8 +221,8 @@ void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
 	void *old, *new;
 
 	/* modifying range */
-	m_start = mem->range.start;
-	m_end = mem->range.end;
+	m_start = mem->range.start & ~(u64)EFI_PAGE_SIZE;
+	m_end = ALIGN(mem->range.end, EFI_PAGE_SIZE) - 1;
 	m_attr = mem->attribute;
 
 	for (old = old_memmap->map, new = buf;
-- 
2.7.4

Re: Cannot load linux after recent efi-related changes

[Matt Fleming]

On Sun, 18 Sep, at 04:14:45AM, Mike Krinkin wrote:
> 
> diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
> index cd96086..34322d1 100644
> --- a/drivers/firmware/efi/memmap.c
> +++ b/drivers/firmware/efi/memmap.c
> @@ -221,8 +221,8 @@ void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
>  	void *old, *new;
>  
>  	/* modifying range */
> -	m_start = mem->range.start;
> -	m_end = mem->range.end;
> +	m_start = mem->range.start & ~(u64)EFI_PAGE_SIZE;
> +	m_end = ALIGN(mem->range.end, EFI_PAGE_SIZE) - 1;
>  	m_attr = mem->attribute;
>  
>  	for (old = old_memmap->map, new = buf;

Thanks for the analysis and patch Mike, but this needs fixing further
up the call stack so that we don't map things the caller didn't
expect.

This bug was also reported in this thread,

  https://lkml.kernel.org/r/1474005912.3930.10.camel@gmail.com

Could you try this patch?

---->8----

>From 7e750e3289a44fe3ad693bde45aea1ad8577dd2a Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt@codeblueprint.co.uk>
Date: Fri, 16 Sep 2016 15:12:47 +0100
Subject: [PATCH] x86/efi: Round EFI memmap reservations to EFI_PAGE_SIZE

Mike Galbraith reported that his machine started rebooting during boot
after,

  commit 8e80632fb23f ("efi/esrt: Use efi_mem_reserve() and avoid a kmalloc()")

The ESRT table on his machine is 56 bytes and at no point in the
efi_arch_mem_reserve() call path is that size rounded up to
EFI_PAGE_SIZE, nor is the start address on an EFI_PAGE_SIZE boundary.

Since the EFI memory map only deals with whole pages, inserting an EFI
memory region with 56 bytes results in a new entry covering zero
pages, and completely screws up the calculations for the old regions
that were trimmed.

Round all sizes upwards, and start addresses downwards, to the nearest
EFI_PAGE_SIZE boundary.

Additionally, efi_memmap_insert() expects the mem::range::end value to
be one less than the end address for the region.

Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Reported-by: Mike Krinkin <krinkin.m.u@gmail.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
 arch/x86/platform/efi/quirks.c |  6 +++++-
 drivers/firmware/efi/memmap.c  | 11 +++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index f14b7a9da24b..10aca63a50d7 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -201,8 +201,12 @@ void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size)
 		return;
 	}
 
+	size += addr % EFI_PAGE_SIZE;
+	size = round_up(size, EFI_PAGE_SIZE);
+	addr = round_down(addr, EFI_PAGE_SIZE);
+
 	mr.range.start = addr;
-	mr.range.end = addr + size;
+	mr.range.end = addr + size - 1;
 	mr.attribute = md.attribute | EFI_MEMORY_RUNTIME;
 
 	num_entries = efi_memmap_split_count(&md, &mr.range);
diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
index cd96086fd851..f03ddecd232b 100644
--- a/drivers/firmware/efi/memmap.c
+++ b/drivers/firmware/efi/memmap.c
@@ -225,6 +225,17 @@ void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
 	m_end = mem->range.end;
 	m_attr = mem->attribute;
 
+	/*
+	 * The EFI memory map deals with regions in EFI_PAGE_SIZE
+	 * units. Ensure that the region described by 'mem' is aligned
+	 * correctly.
+	 */
+	if (!IS_ALIGNED(m_start, EFI_PAGE_SIZE) ||
+	    !IS_ALIGNED(m_end + 1, EFI_PAGE_SIZE)) {
+		WARN_ON(1);
+		return;
+	}
+
 	for (old = old_memmap->map, new = buf;
 	     old < old_memmap->map_end;
 	     old += old_memmap->desc_size, new += old_memmap->desc_size) {
-- 
2.9.3

Re: Cannot load linux after recent efi-related changes

[Mike Krinkin]

On Mon, Sep 19, 2016 at 12:14:24PM +0100, Matt Fleming wrote:
> On Sun, 18 Sep, at 04:14:45AM, Mike Krinkin wrote:
> > 
> > diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
> > index cd96086..34322d1 100644
> > --- a/drivers/firmware/efi/memmap.c
> > +++ b/drivers/firmware/efi/memmap.c
> > @@ -221,8 +221,8 @@ void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
> >  	void *old, *new;
> >  
> >  	/* modifying range */
> > -	m_start = mem->range.start;
> > -	m_end = mem->range.end;
> > +	m_start = mem->range.start & ~(u64)EFI_PAGE_SIZE;
> > +	m_end = ALIGN(mem->range.end, EFI_PAGE_SIZE) - 1;
> >  	m_attr = mem->attribute;
> >  
> >  	for (old = old_memmap->map, new = buf;
> 
> Thanks for the analysis and patch Mike, but this needs fixing further
> up the call stack so that we don't map things the caller didn't
> expect.
> 
> This bug was also reported in this thread,
> 
>   https://lkml.kernel.org/r/1474005912.3930.10.camel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

Sorry, i haven't seen that.

> 
> Could you try this patch?

Works fine for me.

> 
> ---->8----
> 
> From 7e750e3289a44fe3ad693bde45aea1ad8577dd2a Mon Sep 17 00:00:00 2001
> From: Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
> Date: Fri, 16 Sep 2016 15:12:47 +0100
> Subject: [PATCH] x86/efi: Round EFI memmap reservations to EFI_PAGE_SIZE
> 
> Mike Galbraith reported that his machine started rebooting during boot
> after,
> 
>   commit 8e80632fb23f ("efi/esrt: Use efi_mem_reserve() and avoid a kmalloc()")
> 
> The ESRT table on his machine is 56 bytes and at no point in the
> efi_arch_mem_reserve() call path is that size rounded up to
> EFI_PAGE_SIZE, nor is the start address on an EFI_PAGE_SIZE boundary.
> 
> Since the EFI memory map only deals with whole pages, inserting an EFI
> memory region with 56 bytes results in a new entry covering zero
> pages, and completely screws up the calculations for the old regions
> that were trimmed.
> 
> Round all sizes upwards, and start addresses downwards, to the nearest
> EFI_PAGE_SIZE boundary.
> 
> Additionally, efi_memmap_insert() expects the mem::range::end value to
> be one less than the end address for the region.
> 
> Reported-by: Mike Galbraith <umgwanakikbuti-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Reported-by: Mike Krinkin <krinkin.m.u-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Cc: Peter Jones <pjones-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Cc: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> Cc: Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>
> Cc: Taku Izumi <izumi.taku-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
> Signed-off-by: Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
> ---
>  arch/x86/platform/efi/quirks.c |  6 +++++-
>  drivers/firmware/efi/memmap.c  | 11 +++++++++++
>  2 files changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> index f14b7a9da24b..10aca63a50d7 100644
> --- a/arch/x86/platform/efi/quirks.c
> +++ b/arch/x86/platform/efi/quirks.c
> @@ -201,8 +201,12 @@ void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size)
>  		return;
>  	}
>  
> +	size += addr % EFI_PAGE_SIZE;
> +	size = round_up(size, EFI_PAGE_SIZE);
> +	addr = round_down(addr, EFI_PAGE_SIZE);
> +
>  	mr.range.start = addr;
> -	mr.range.end = addr + size;
> +	mr.range.end = addr + size - 1;
>  	mr.attribute = md.attribute | EFI_MEMORY_RUNTIME;
>  
>  	num_entries = efi_memmap_split_count(&md, &mr.range);
> diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
> index cd96086fd851..f03ddecd232b 100644
> --- a/drivers/firmware/efi/memmap.c
> +++ b/drivers/firmware/efi/memmap.c
> @@ -225,6 +225,17 @@ void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
>  	m_end = mem->range.end;
>  	m_attr = mem->attribute;
>  
> +	/*
> +	 * The EFI memory map deals with regions in EFI_PAGE_SIZE
> +	 * units. Ensure that the region described by 'mem' is aligned
> +	 * correctly.
> +	 */
> +	if (!IS_ALIGNED(m_start, EFI_PAGE_SIZE) ||
> +	    !IS_ALIGNED(m_end + 1, EFI_PAGE_SIZE)) {
> +		WARN_ON(1);
> +		return;
> +	}
> +
>  	for (old = old_memmap->map, new = buf;
>  	     old < old_memmap->map_end;
>  	     old += old_memmap->desc_size, new += old_memmap->desc_size) {
> -- 
> 2.9.3
> 

Re: Cannot load linux after recent efi-related changes

[Matt Fleming]

On Mon, 19 Sep, at 02:36:36PM, Mike Krinkin wrote:
> On Mon, Sep 19, 2016 at 12:14:24PM +0100, Matt Fleming wrote:
> > On Sun, 18 Sep, at 04:14:45AM, Mike Krinkin wrote:
> > > 
> > > diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
> > > index cd96086..34322d1 100644
> > > --- a/drivers/firmware/efi/memmap.c
> > > +++ b/drivers/firmware/efi/memmap.c
> > > @@ -221,8 +221,8 @@ void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
> > >  	void *old, *new;
> > >  
> > >  	/* modifying range */
> > > -	m_start = mem->range.start;
> > > -	m_end = mem->range.end;
> > > +	m_start = mem->range.start & ~(u64)EFI_PAGE_SIZE;
> > > +	m_end = ALIGN(mem->range.end, EFI_PAGE_SIZE) - 1;
> > >  	m_attr = mem->attribute;
> > >  
> > >  	for (old = old_memmap->map, new = buf;
> > 
> > Thanks for the analysis and patch Mike, but this needs fixing further
> > up the call stack so that we don't map things the caller didn't
> > expect.
> > 
> > This bug was also reported in this thread,
> > 
> >   https://lkml.kernel.org/r/1474005912.3930.10.camel@gmail.com
> 
> Sorry, i haven't seen that.
 
No problem.

> > 
> > Could you try this patch?
> 
> Works fine for me.

Thanks, I've added your Tested-by.