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authorGuenter Roeck <linux@roeck-us.net>2020-01-30 18:11:59 -0800
committerBorislav Petkov <bp@suse.de>2020-03-19 11:58:13 +0100
commitbac59d18c7018a2fd5e800a1e72a8271bf404977 (patch)
tree7d047657b3491b41a1049a2aff514c7ef141b369 /arch/x86/include
parent6f8f0dc980028e98ae339876a8403edae4d20e39 (diff)
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
Diffstat (limited to 'arch/x86/include')
-rw-r--r--arch/x86/include/asm/sections.h20
1 files changed, 20 insertions, 0 deletions
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 */

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