[ Adding Greg and Kamal ]
On Wed, Jan 06, 2016 at 01:31:55PM +0000, Matt Fleming wrote:
> On Wed, 06 Jan, at 11:24:55AM, Luis Henriques wrote:
> > On Wed, Jan 06, 2016 at 11:00:31AM +0000, Matt Fleming wrote:
> > > On Wed, 06 Jan, at 11:47:20AM, Paolo Bonzini wrote:
> > > >
> > > > Without testing the problematic scenario explicitly (32-bit UEFI
> > > > kernel), I think this patch and 26/91 should not be backported to
> > > > kernels that do not have 23a0d4e8fa6d.
> > >
> > > I tend to agree.
> >
> > I can see these 2 commits in kernels as old as 3.10 (which definitely do
> > not include 23a0d4e8fa6d). Does this mean these should be reverted from
> > stable kernels that already include these patches? Or would you rather
> > recommend to backport 23a0d4e8fa6d?
>
> That depends on your appetite for risk ;-)
>
Heh, I guess stable kernels aren't really about appetite for risk :-)
> 23a0d4e8fa6d does fix a legitimate bug, albeit one that no one seems
> to have ever hit. Personally, I'd go for backporting 23a0d4e8fa6d.
This commit doesn't seem to be too bad to backport. I'm attaching 2
backports:
- one is for the 3.16 stable kernel,
- the other can be applied to 3.10, 3.12 and 3.13
(For the other kernels, I believe 23a0d4e8fa6d will be a clean
cherry-pick.)
Cheers,
--
Luís
>From 6b58a852d51e7d1991d759c331bc276b2461c4c3 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mi...@kernel.org>
Date: Tue, 3 Mar 2015 07:34:33 +0100
Subject: efi: Disable interrupts around EFI calls, not in the epilog/prolog
calls
commit 23a0d4e8fa6d3a1d7fb819f79bcc0a3739c30ba9 upstream.
Tapasweni Pathak reported that we do a kmalloc() in efi_call_phys_prolog()
on x86-64 while having interrupts disabled, which is a big no-no, as
kmalloc() can sleep.
Solve this by removing the irq disabling from the prolog/epilog calls
around EFI calls: it's unnecessary, as in this stage we are single
threaded in the boot thread, and we don't ever execute this from
interrupt contexts.
Reported-by: Tapasweni Pathak <tapaswenipat...@gmail.com>
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Matt Fleming <matt.flem...@intel.com>
[ luis: backported to 3.10: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriq...@canonical.com>
---
arch/x86/platform/efi/efi.c | 7 +++++++
arch/x86/platform/efi/efi_32.c | 11 +++--------
arch/x86/platform/efi/efi_64.c | 3 ---
3 files changed, 10 insertions(+), 11 deletions(-)
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 6033be9ff81a..3c8bffdc71c8 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -250,12 +250,19 @@ static efi_status_t __init phys_efi_set_virtual_address_map(
efi_memory_desc_t *virtual_map)
{
efi_status_t status;
+ unsigned long flags;
efi_call_phys_prelog();
+
+ /* Disable interrupts around EFI calls: */
+ local_irq_save(flags);
status = efi_call_phys4(efi_phys.set_virtual_address_map,
memory_map_size, descriptor_size,
descriptor_version, virtual_map);
+ local_irq_restore(flags);
+
efi_call_phys_epilog();
+
return status;
}
diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index 40e446941dd7..bebbee05e331 100644
--- a/arch/x86/platform/efi/efi_32.c
+++ b/arch/x86/platform/efi/efi_32.c
@@ -33,19 +33,16 @@
/*
* To make EFI call EFI runtime service in physical addressing mode we need
- * prelog/epilog before/after the invocation to disable interrupt, to
- * claim EFI runtime service handler exclusively and to duplicate a memory in
- * low memory space say 0 - 3G.
+ * prolog/epilog before/after the invocation to claim the EFI runtime service
+ * handler exclusively and to duplicate a memory mapping in low memory space,
+ * say 0 - 3G.
*/
-static unsigned long efi_rt_eflags;
void efi_call_phys_prelog(void)
{
struct desc_ptr gdt_descr;
- local_irq_save(efi_rt_eflags);
-
load_cr3(initial_page_table);
__flush_tlb_all();
@@ -64,6 +61,4 @@ void efi_call_phys_epilog(void)
load_cr3(swapper_pg_dir);
__flush_tlb_all();
-
- local_irq_restore(efi_rt_eflags);
}
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 39a0e7f1f0a3..2f6c1a9734c8 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -40,7 +40,6 @@
#include <asm/fixmap.h>
static pgd_t *save_pgd __initdata;
-static unsigned long efi_flags __initdata;
static void __init early_code_mapping_set_exec(int executable)
{
@@ -66,7 +65,6 @@ void __init efi_call_phys_prelog(void)
int n_pgds;
early_code_mapping_set_exec(1);
- local_irq_save(efi_flags);
n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE);
save_pgd = kmalloc(n_pgds * sizeof(pgd_t), GFP_KERNEL);
@@ -90,7 +88,6 @@ void __init efi_call_phys_epilog(void)
set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), save_pgd[pgd]);
kfree(save_pgd);
__flush_tlb_all();
- local_irq_restore(efi_flags);
early_code_mapping_set_exec(0);
}
>From 466b891857a536af2a9b7ad058e1cc00b702a528 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mi...@kernel.org>
Date: Tue, 3 Mar 2015 07:34:33 +0100
Subject: [PATCH] efi: Disable interrupts around EFI calls, not in the
epilog/prolog calls
commit 23a0d4e8fa6d3a1d7fb819f79bcc0a3739c30ba9 upstream.
Tapasweni Pathak reported that we do a kmalloc() in efi_call_phys_prolog()
on x86-64 while having interrupts disabled, which is a big no-no, as
kmalloc() can sleep.
Solve this by removing the irq disabling from the prolog/epilog calls
around EFI calls: it's unnecessary, as in this stage we are single
threaded in the boot thread, and we don't ever execute this from
interrupt contexts.
Reported-by: Tapasweni Pathak <tapaswenipat...@gmail.com>
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Matt Fleming <matt.flem...@intel.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriq...@canonical.com>
---
arch/x86/platform/efi/efi.c | 7 +++++++
arch/x86/platform/efi/efi_32.c | 11 +++--------
arch/x86/platform/efi/efi_64.c | 3 ---
3 files changed, 10 insertions(+), 11 deletions(-)
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 5bbb477f5c2a..09c8ac286cd5 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -236,12 +236,19 @@ static efi_status_t __init phys_efi_set_virtual_address_map(
efi_memory_desc_t *virtual_map)
{
efi_status_t status;
+ unsigned long flags;
efi_call_phys_prelog();
+
+ /* Disable interrupts around EFI calls: */
+ local_irq_save(flags);
status = efi_call_phys(efi_phys.set_virtual_address_map,
memory_map_size, descriptor_size,
descriptor_version, virtual_map);
+ local_irq_restore(flags);
+
efi_call_phys_epilog();
+
return status;
}
diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index 9ee3491e31fb..be4e7eb41674 100644
--- a/arch/x86/platform/efi/efi_32.c
+++ b/arch/x86/platform/efi/efi_32.c
@@ -33,11 +33,10 @@
/*
* To make EFI call EFI runtime service in physical addressing mode we need
- * prelog/epilog before/after the invocation to disable interrupt, to
- * claim EFI runtime service handler exclusively and to duplicate a memory in
- * low memory space say 0 - 3G.
+ * prolog/epilog before/after the invocation to claim the EFI runtime service
+ * handler exclusively and to duplicate a memory mapping in low memory space,
+ * say 0 - 3G.
*/
-static unsigned long efi_rt_eflags;
void efi_sync_low_kernel_mappings(void) {}
void __init efi_dump_pagetable(void) {}
@@ -59,8 +58,6 @@ void efi_call_phys_prelog(void)
{
struct desc_ptr gdt_descr;
- local_irq_save(efi_rt_eflags);
-
load_cr3(initial_page_table);
__flush_tlb_all();
@@ -79,8 +76,6 @@ void efi_call_phys_epilog(void)
load_cr3(swapper_pg_dir);
__flush_tlb_all();
-
- local_irq_restore(efi_rt_eflags);
}
void __init efi_runtime_mkexec(void)
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 290d397e1dd9..8139b4858403 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -42,7 +42,6 @@
#include <asm/time.h>
static pgd_t *save_pgd __initdata;
-static unsigned long efi_flags __initdata;
/*
* We allocate runtime services regions bottom-up, starting from -4G, i.e.
@@ -89,7 +88,6 @@ void __init efi_call_phys_prelog(void)
return;
early_code_mapping_set_exec(1);
- local_irq_save(efi_flags);
n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE);
save_pgd = kmalloc(n_pgds * sizeof(pgd_t), GFP_KERNEL);
@@ -117,7 +115,6 @@ void __init efi_call_phys_epilog(void)
set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), save_pgd[pgd]);
kfree(save_pgd);
__flush_tlb_all();
- local_irq_restore(efi_flags);
early_code_mapping_set_exec(0);
}
