* [PATCH] x86: Fix static memory detection
@ 2020-01-31 2:11 Guenter Roeck
2020-03-17 13:44 ` Guenter Roeck
2020-03-19 14:17 ` [tip: x86/boot] x86/setup: " tip-bot2 for Guenter Roeck
0 siblings, 2 replies; 3+ messages in thread
From: Guenter Roeck @ 2020-01-31 2:11 UTC (permalink / raw)
To: x86
Cc: Thomas Gleixner, Ingo Molnar, linux-kernel, Borislav Petkov,
H . Peter Anvin, Guenter Roeck
When booting x86 images in qemu, the following warning is seen
randomly if DEBUG_LOCKDEP is enabled.
WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:1119
lockdep_register_key+0xc0/0x100
static_obj() returns true if an address is between _stext and _end.
On x86, this includes the brk memory space. Problem is that this
memory block is not static on x86; its unused portions are released
after init and can be allocated. This results in the observed warning
if a lockdep object is allocated from this memory.
Solve the problem by implementing arch_is_kernel_initmem_freed()
for x86 and have it return true if an address is within the released
memory range.
The same problem was solved for s390 with commit 7a5da02de8d6e
("locking/lockdep: check for freed initmem in static_obj()"), which
introduced arch_is_kernel_initmem_freed().
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
arch/x86/include/asm/sections.h | 20 ++++++++++++++++++++
arch/x86/kernel/setup.c | 1 -
2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
index 036c360910c5..a6e8373a5170 100644
--- a/arch/x86/include/asm/sections.h
+++ b/arch/x86/include/asm/sections.h
@@ -2,6 +2,8 @@
#ifndef _ASM_X86_SECTIONS_H
#define _ASM_X86_SECTIONS_H
+#define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed
+
#include <asm-generic/sections.h>
#include <asm/extable.h>
@@ -14,4 +16,22 @@ extern char __end_rodata_hpage_align[];
extern char __end_of_kernel_reserve[];
+extern unsigned long _brk_start, _brk_end;
+
+static inline bool arch_is_kernel_initmem_freed(unsigned long addr)
+{
+ /*
+ * If _brk_start has not been cleared, brk allocation is incomplete,
+ * and we can not make assumptions about its use.
+ */
+ if (_brk_start)
+ return 0;
+
+ /*
+ * After brk allocation is complete, space between _brk_end and _end
+ * is available for allocation.
+ */
+ return addr >= _brk_end && addr < (unsigned long)&_end;
+}
+
#endif /* _ASM_X86_SECTIONS_H */
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 1e4c20a1efec..08f5ceed70e0 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -64,7 +64,6 @@ RESERVE_BRK(dmi_alloc, 65536);
* at link time, with RESERVE_BRK*() facility reserving additional
* chunks.
*/
-static __initdata
unsigned long _brk_start = (unsigned long)__brk_base;
unsigned long _brk_end = (unsigned long)__brk_base;
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] x86: Fix static memory detection
2020-01-31 2:11 [PATCH] x86: Fix static memory detection Guenter Roeck
@ 2020-03-17 13:44 ` Guenter Roeck
2020-03-19 14:17 ` [tip: x86/boot] x86/setup: " tip-bot2 for Guenter Roeck
1 sibling, 0 replies; 3+ messages in thread
From: Guenter Roeck @ 2020-03-17 13:44 UTC (permalink / raw)
To: x86
Cc: Thomas Gleixner, Ingo Molnar, linux-kernel, Borislav Petkov,
H . Peter Anvin
ping ... I still see this problem.
Guenter
On Thu, Jan 30, 2020 at 06:11:59PM -0800, Guenter Roeck wrote:
> When booting x86 images in qemu, the following warning is seen
> randomly if DEBUG_LOCKDEP is enabled.
>
> WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:1119
> lockdep_register_key+0xc0/0x100
>
> static_obj() returns true if an address is between _stext and _end.
> On x86, this includes the brk memory space. Problem is that this
> memory block is not static on x86; its unused portions are released
> after init and can be allocated. This results in the observed warning
> if a lockdep object is allocated from this memory.
>
> Solve the problem by implementing arch_is_kernel_initmem_freed()
> for x86 and have it return true if an address is within the released
> memory range.
>
> The same problem was solved for s390 with commit 7a5da02de8d6e
> ("locking/lockdep: check for freed initmem in static_obj()"), which
> introduced arch_is_kernel_initmem_freed().
>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
> arch/x86/include/asm/sections.h | 20 ++++++++++++++++++++
> arch/x86/kernel/setup.c | 1 -
> 2 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
> index 036c360910c5..a6e8373a5170 100644
> --- a/arch/x86/include/asm/sections.h
> +++ b/arch/x86/include/asm/sections.h
> @@ -2,6 +2,8 @@
> #ifndef _ASM_X86_SECTIONS_H
> #define _ASM_X86_SECTIONS_H
>
> +#define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed
> +
> #include <asm-generic/sections.h>
> #include <asm/extable.h>
>
> @@ -14,4 +16,22 @@ extern char __end_rodata_hpage_align[];
>
> extern char __end_of_kernel_reserve[];
>
> +extern unsigned long _brk_start, _brk_end;
> +
> +static inline bool arch_is_kernel_initmem_freed(unsigned long addr)
> +{
> + /*
> + * If _brk_start has not been cleared, brk allocation is incomplete,
> + * and we can not make assumptions about its use.
> + */
> + if (_brk_start)
> + return 0;
> +
> + /*
> + * After brk allocation is complete, space between _brk_end and _end
> + * is available for allocation.
> + */
> + return addr >= _brk_end && addr < (unsigned long)&_end;
> +}
> +
> #endif /* _ASM_X86_SECTIONS_H */
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 1e4c20a1efec..08f5ceed70e0 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -64,7 +64,6 @@ RESERVE_BRK(dmi_alloc, 65536);
> * at link time, with RESERVE_BRK*() facility reserving additional
> * chunks.
> */
> -static __initdata
> unsigned long _brk_start = (unsigned long)__brk_base;
> unsigned long _brk_end = (unsigned long)__brk_base;
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* [tip: x86/boot] x86/setup: Fix static memory detection
2020-01-31 2:11 [PATCH] x86: Fix static memory detection Guenter Roeck
2020-03-17 13:44 ` Guenter Roeck
@ 2020-03-19 14:17 ` tip-bot2 for Guenter Roeck
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot2 for Guenter Roeck @ 2020-03-19 14:17 UTC (permalink / raw)
To: linux-tip-commits
Cc: Guenter Roeck, Borislav Petkov, Peter Zijlstra, x86, LKML
The following commit has been merged into the x86/boot branch of tip:
Commit-ID: bac59d18c7018a2fd5e800a1e72a8271bf404977
Gitweb: https://git.kernel.org/tip/bac59d18c7018a2fd5e800a1e72a8271bf404977
Author: Guenter Roeck <linux@roeck-us.net>
AuthorDate: Thu, 30 Jan 2020 18:11:59 -08:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Thu, 19 Mar 2020 11:58:13 +01:00
x86/setup: Fix static memory detection
When booting x86 images in qemu, the following warning is seen randomly
if DEBUG_LOCKDEP is enabled.
WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:1119
lockdep_register_key+0xc0/0x100
static_obj() returns true if an address is between _stext and _end.
On x86, this includes the brk memory space. Problem is that this memory
block is not static on x86; its unused portions are released after init
and can be allocated. This results in the observed warning if a lockdep
object is allocated from this memory.
Solve the problem by implementing arch_is_kernel_initmem_freed() for
x86 and have it return true if an address is within the released memory
range.
The same problem was solved for s390 with commit
7a5da02de8d6e ("locking/lockdep: check for freed initmem in static_obj()"),
which introduced arch_is_kernel_initmem_freed().
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200131021159.9178-1-linux@roeck-us.net
---
arch/x86/include/asm/sections.h | 20 ++++++++++++++++++++
arch/x86/kernel/setup.c | 1 -
2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
index 036c360..a6e8373 100644
--- a/arch/x86/include/asm/sections.h
+++ b/arch/x86/include/asm/sections.h
@@ -2,6 +2,8 @@
#ifndef _ASM_X86_SECTIONS_H
#define _ASM_X86_SECTIONS_H
+#define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed
+
#include <asm-generic/sections.h>
#include <asm/extable.h>
@@ -14,4 +16,22 @@ extern char __end_rodata_hpage_align[];
extern char __end_of_kernel_reserve[];
+extern unsigned long _brk_start, _brk_end;
+
+static inline bool arch_is_kernel_initmem_freed(unsigned long addr)
+{
+ /*
+ * If _brk_start has not been cleared, brk allocation is incomplete,
+ * and we can not make assumptions about its use.
+ */
+ if (_brk_start)
+ return 0;
+
+ /*
+ * After brk allocation is complete, space between _brk_end and _end
+ * is available for allocation.
+ */
+ return addr >= _brk_end && addr < (unsigned long)&_end;
+}
+
#endif /* _ASM_X86_SECTIONS_H */
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index a74262c..e6b5450 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -64,7 +64,6 @@ RESERVE_BRK(dmi_alloc, 65536);
* at link time, with RESERVE_BRK*() facility reserving additional
* chunks.
*/
-static __initdata
unsigned long _brk_start = (unsigned long)__brk_base;
unsigned long _brk_end = (unsigned long)__brk_base;
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2020-01-31 2:11 [PATCH] x86: Fix static memory detection Guenter Roeck
2020-03-17 13:44 ` Guenter Roeck
2020-03-19 14:17 ` [tip: x86/boot] x86/setup: " tip-bot2 for Guenter Roeck
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