[01/11] x86/efi: Allocate e820 buffer before calling efi_exit_boot_service

Message ID 20181129171230.18699-2-ard.biesheuvel@linaro.org
State New
Headers show
Series
  • EFI updates
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Commit Message

Ard Biesheuvel Nov. 29, 2018, 5:12 p.m.
From: Eric Snowberg <eric.snowberg@oracle.com>


Commit d64934019f6c ("x86/efi: Use efi_exit_boot_services()")
introduced a regression on systems with large memory maps
causing them to hang on boot. The first "goto get_map" that was removed
from exit_boot insured there was enough room for the memory map when
efi_call_early(exit_boot_services) was called. This happens when
(nr_desc > ARRAY_SIZE(params->e820_table).

Chain of events:
  exit_boot()
    efi_exit_boot_services()
      efi_get_memory_map <- at this point the mm can't grow over 8 desc
      priv_func()
        exit_boot_func()
          allocate_e820ext() <- new mm grows over 8 desc from e820 alloc
      efi_call_early(exit_boot_services) <- mm key doesn't match so retry
      efi_call_early(get_memory_map) <- not enough room for new mm
      system hangs

This patch allocates the e820 buffer before calling efi_exit_boot_services
and fixes the regression.

Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---
 arch/x86/boot/compressed/eboot.c | 65 ++++++++++++++++++++------------
 1 file changed, 41 insertions(+), 24 deletions(-)

-- 
2.19.1

Comments

Ingo Molnar Nov. 30, 2018, 8:36 a.m. | #1
* Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:

> On Fri, 30 Nov 2018 at 08:29, Ingo Molnar <mingo@kernel.org> wrote:

> >

> >

> > * Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:

> >

> > > From: Eric Snowberg <eric.snowberg@oracle.com>

> > >

> > > Commit d64934019f6c ("x86/efi: Use efi_exit_boot_services()")

> > > introduced a regression on systems with large memory maps

> > > causing them to hang on boot. The first "goto get_map" that was removed

> > > from exit_boot insured there was enough room for the memory map when

> > > efi_call_early(exit_boot_services) was called. This happens when

> > > (nr_desc > ARRAY_SIZE(params->e820_table).

> > >

> > > Chain of events:

> > >   exit_boot()

> > >     efi_exit_boot_services()

> > >       efi_get_memory_map <- at this point the mm can't grow over 8 desc

> > >       priv_func()

> > >         exit_boot_func()

> > >           allocate_e820ext() <- new mm grows over 8 desc from e820 alloc

> > >       efi_call_early(exit_boot_services) <- mm key doesn't match so retry

> > >       efi_call_early(get_memory_map) <- not enough room for new mm

> > >       system hangs

> > >

> > > This patch allocates the e820 buffer before calling efi_exit_boot_services

> > > and fixes the regression.

> > >

> > > Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>

> > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

> > > ---

> > >  arch/x86/boot/compressed/eboot.c | 65 ++++++++++++++++++++------------

> > >  1 file changed, 41 insertions(+), 24 deletions(-)

> >

> > Any objections against marking this for -stable and filing it in

> > efi/urgent? Boot hangs are show-stopper bugs, so distributions would want

> > to backport this fix anyway.

> >

> 

> No objections per se, but this is the kind of patch that might go the

> other way as well, so I would prefer to give it some wider coverage at

> first, given how quickly patches are taken into -stable.

> 

> I can make a note of it and send it to Greg halfway into the next -rc cycle.


So there should be at least one week of testing because I just sent the 
EFI fixes to Linus, plus -stable gets at least a week of testing as well.

Also, in practice, -next and early -rc cycles get only the fraction of 
testing that later -rc's or -stable gets. So if we want this in -stable 
we might as well do it now - or the real testing gets delayed by ~3 
months in practice. That's also the pattern encouraged by Linus: if it's 
a fix that matters then it should be upstreamed with the usual regression 
fixes.

Anyway, your call!

Thanks,

	Ingo

Patch

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 8b4c5e001157..f7bad07bb251 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -1,3 +1,4 @@ 
+
 /* -----------------------------------------------------------------------
  *
  *   Copyright 2011 Intel Corporation; author Matt Fleming
@@ -634,37 +635,54 @@  static efi_status_t alloc_e820ext(u32 nr_desc, struct setup_data **e820ext,
 	return status;
 }
 
+static efi_status_t allocate_e820(struct boot_params *params,
+				  struct setup_data **e820ext,
+				  u32 *e820ext_size)
+{
+	unsigned long map_size, desc_size, buff_size;
+	struct efi_boot_memmap boot_map;
+	efi_memory_desc_t *map;
+	efi_status_t status;
+	__u32 nr_desc;
+
+	boot_map.map =		&map;
+	boot_map.map_size =	&map_size;
+	boot_map.desc_size =	&desc_size;
+	boot_map.desc_ver =	NULL;
+	boot_map.key_ptr =	NULL;
+	boot_map.buff_size =	&buff_size;
+
+	status = efi_get_memory_map(sys_table, &boot_map);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	nr_desc = buff_size / desc_size;
+
+	if (nr_desc > ARRAY_SIZE(params->e820_table)) {
+		u32 nr_e820ext = nr_desc - ARRAY_SIZE(params->e820_table);
+
+		status = alloc_e820ext(nr_e820ext, e820ext, e820ext_size);
+		if (status != EFI_SUCCESS)
+			return status;
+	}
+
+	return EFI_SUCCESS;
+}
+
 struct exit_boot_struct {
 	struct boot_params	*boot_params;
 	struct efi_info		*efi;
-	struct setup_data	*e820ext;
-	__u32			e820ext_size;
 };
 
 static efi_status_t exit_boot_func(efi_system_table_t *sys_table_arg,
 				   struct efi_boot_memmap *map,
 				   void *priv)
 {
-	static bool first = true;
 	const char *signature;
 	__u32 nr_desc;
 	efi_status_t status;
 	struct exit_boot_struct *p = priv;
 
-	if (first) {
-		nr_desc = *map->buff_size / *map->desc_size;
-		if (nr_desc > ARRAY_SIZE(p->boot_params->e820_table)) {
-			u32 nr_e820ext = nr_desc -
-					ARRAY_SIZE(p->boot_params->e820_table);
-
-			status = alloc_e820ext(nr_e820ext, &p->e820ext,
-					       &p->e820ext_size);
-			if (status != EFI_SUCCESS)
-				return status;
-		}
-		first = false;
-	}
-
 	signature = efi_is_64bit() ? EFI64_LOADER_SIGNATURE
 				   : EFI32_LOADER_SIGNATURE;
 	memcpy(&p->efi->efi_loader_signature, signature, sizeof(__u32));
@@ -687,8 +705,8 @@  static efi_status_t exit_boot(struct boot_params *boot_params, void *handle)
 {
 	unsigned long map_sz, key, desc_size, buff_size;
 	efi_memory_desc_t *mem_map;
-	struct setup_data *e820ext;
-	__u32 e820ext_size;
+	struct setup_data *e820ext = NULL;
+	__u32 e820ext_size = 0;
 	efi_status_t status;
 	__u32 desc_version;
 	struct efi_boot_memmap map;
@@ -702,8 +720,10 @@  static efi_status_t exit_boot(struct boot_params *boot_params, void *handle)
 	map.buff_size		= &buff_size;
 	priv.boot_params	= boot_params;
 	priv.efi		= &boot_params->efi_info;
-	priv.e820ext		= NULL;
-	priv.e820ext_size	= 0;
+
+	status = allocate_e820(boot_params, &e820ext, &e820ext_size);
+	if (status != EFI_SUCCESS)
+		return status;
 
 	/* Might as well exit boot services now */
 	status = efi_exit_boot_services(sys_table, handle, &map, &priv,
@@ -711,9 +731,6 @@  static efi_status_t exit_boot(struct boot_params *boot_params, void *handle)
 	if (status != EFI_SUCCESS)
 		return status;
 
-	e820ext			= priv.e820ext;
-	e820ext_size		= priv.e820ext_size;
-
 	/* Historic? */
 	boot_params->alt_mem_k	= 32 * 1024;