* [PATCH 1/3] mm: Make generic arch_is_kernel_initmem_freed() do what it says
@ 2021-09-24 13:48 Christophe Leroy
2021-09-24 13:48 ` [PATCH 2/3] powerpc: Use generic version of arch_is_kernel_initmem_freed() Christophe Leroy
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Christophe Leroy @ 2021-09-24 13:48 UTC (permalink / raw)
To: Andrew Morton, arnd
Cc: Christophe Leroy, linux-kernel, linux-mm, linux-s390,
linuxppc-dev, linux-arch, Gerald Schaefer
Commit 7a5da02de8d6 ("locking/lockdep: check for freed initmem in
static_obj()") added arch_is_kernel_initmem_freed() which is supposed
to report whether an object is part of already freed init memory.
For the time being, the generic version of arch_is_kernel_initmem_freed()
always reports 'false', allthough free_initmem() is generically called
on all architectures.
Therefore, change the generic version of arch_is_kernel_initmem_freed()
to check whether free_initmem() has been called. If so, then check
if a given address falls into init memory.
In order to use function init_section_contains(), the fonction is
moved at the end of asm-generic/section.h
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
include/asm-generic/sections.h | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index d16302d3eb59..d1e5bb2c6b72 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -80,20 +80,6 @@ static inline int arch_is_kernel_data(unsigned long addr)
}
#endif
-/*
- * Check if an address is part of freed initmem. This is needed on architectures
- * with virt == phys kernel mapping, for code that wants to check if an address
- * is part of a static object within [_stext, _end]. After initmem is freed,
- * memory can be allocated from it, and such allocations would then have
- * addresses within the range [_stext, _end].
- */
-#ifndef arch_is_kernel_initmem_freed
-static inline int arch_is_kernel_initmem_freed(unsigned long addr)
-{
- return 0;
-}
-#endif
-
/**
* memory_contains - checks if an object is contained within a memory region
* @begin: virtual address of the beginning of the memory region
@@ -172,4 +158,21 @@ static inline bool is_kernel_rodata(unsigned long addr)
addr < (unsigned long)__end_rodata;
}
+/*
+ * Check if an address is part of freed initmem. This is needed on architectures
+ * with virt == phys kernel mapping, for code that wants to check if an address
+ * is part of a static object within [_stext, _end]. After initmem is freed,
+ * memory can be allocated from it, and such allocations would then have
+ * addresses within the range [_stext, _end].
+ */
+#ifndef arch_is_kernel_initmem_freed
+static inline int arch_is_kernel_initmem_freed(unsigned long addr)
+{
+ if (system_state < SYSTEM_RUNNING)
+ return 0;
+
+ return init_section_contains((void *)addr, 1);
+}
+#endif
+
#endif /* _ASM_GENERIC_SECTIONS_H_ */
--
2.31.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 2/3] powerpc: Use generic version of arch_is_kernel_initmem_freed()
2021-09-24 13:48 [PATCH 1/3] mm: Make generic arch_is_kernel_initmem_freed() do what it says Christophe Leroy
@ 2021-09-24 13:48 ` Christophe Leroy
2021-09-24 13:48 ` [PATCH 3/3] s390: " Christophe Leroy
2021-09-27 13:11 ` [PATCH 1/3] mm: Make generic arch_is_kernel_initmem_freed() do what it says Michael Ellerman
2 siblings, 0 replies; 5+ messages in thread
From: Christophe Leroy @ 2021-09-24 13:48 UTC (permalink / raw)
To: Andrew Morton, arnd
Cc: Christophe Leroy, linux-kernel, linux-mm, linux-s390,
linuxppc-dev, linux-arch
Generic version of arch_is_kernel_initmem_freed() now does the same
as powerpc version.
Remove the powerpc version.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/include/asm/sections.h | 13 -------------
1 file changed, 13 deletions(-)
diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index 6e4af4492a14..79cb7a25a5fb 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h
@@ -6,21 +6,8 @@
#include <linux/elf.h>
#include <linux/uaccess.h>
-#define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed
-
#include <asm-generic/sections.h>
-extern bool init_mem_is_free;
-
-static inline int arch_is_kernel_initmem_freed(unsigned long addr)
-{
- if (!init_mem_is_free)
- return 0;
-
- return addr >= (unsigned long)__init_begin &&
- addr < (unsigned long)__init_end;
-}
-
extern char __head_end[];
#ifdef __powerpc64__
--
2.31.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 3/3] s390: Use generic version of arch_is_kernel_initmem_freed()
2021-09-24 13:48 [PATCH 1/3] mm: Make generic arch_is_kernel_initmem_freed() do what it says Christophe Leroy
2021-09-24 13:48 ` [PATCH 2/3] powerpc: Use generic version of arch_is_kernel_initmem_freed() Christophe Leroy
@ 2021-09-24 13:48 ` Christophe Leroy
2021-09-27 13:11 ` [PATCH 1/3] mm: Make generic arch_is_kernel_initmem_freed() do what it says Michael Ellerman
2 siblings, 0 replies; 5+ messages in thread
From: Christophe Leroy @ 2021-09-24 13:48 UTC (permalink / raw)
To: Andrew Morton, arnd
Cc: Christophe Leroy, linux-kernel, linux-mm, linux-s390,
linuxppc-dev, linux-arch, Gerald Schaefer
Generic version of arch_is_kernel_initmem_freed() now does the same
as s390 version.
Remove the s390 version.
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/s390/include/asm/sections.h | 12 ------------
arch/s390/mm/init.c | 3 ---
2 files changed, 15 deletions(-)
diff --git a/arch/s390/include/asm/sections.h b/arch/s390/include/asm/sections.h
index 85881dd48022..3fecaa4e8b74 100644
--- a/arch/s390/include/asm/sections.h
+++ b/arch/s390/include/asm/sections.h
@@ -2,20 +2,8 @@
#ifndef _S390_SECTIONS_H
#define _S390_SECTIONS_H
-#define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed
-
#include <asm-generic/sections.h>
-extern bool initmem_freed;
-
-static inline int arch_is_kernel_initmem_freed(unsigned long addr)
-{
- if (!initmem_freed)
- return 0;
- return addr >= (unsigned long)__init_begin &&
- addr < (unsigned long)__init_end;
-}
-
/*
* .boot.data section contains variables "shared" between the decompressor and
* the decompressed kernel. The decompressor will store values in them, and
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index a04faf49001a..8c6f258a6183 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -58,8 +58,6 @@ unsigned long empty_zero_page, zero_page_mask;
EXPORT_SYMBOL(empty_zero_page);
EXPORT_SYMBOL(zero_page_mask);
-bool initmem_freed;
-
static void __init setup_zero_pages(void)
{
unsigned int order;
@@ -214,7 +212,6 @@ void __init mem_init(void)
void free_initmem(void)
{
- initmem_freed = true;
__set_memory((unsigned long)_sinittext,
(unsigned long)(_einittext - _sinittext) >> PAGE_SHIFT,
SET_MEMORY_RW | SET_MEMORY_NX);
--
2.31.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH 1/3] mm: Make generic arch_is_kernel_initmem_freed() do what it says
2021-09-24 13:48 [PATCH 1/3] mm: Make generic arch_is_kernel_initmem_freed() do what it says Christophe Leroy
2021-09-24 13:48 ` [PATCH 2/3] powerpc: Use generic version of arch_is_kernel_initmem_freed() Christophe Leroy
2021-09-24 13:48 ` [PATCH 3/3] s390: " Christophe Leroy
@ 2021-09-27 13:11 ` Michael Ellerman
2021-09-27 13:51 ` Christophe Leroy
2 siblings, 1 reply; 5+ messages in thread
From: Michael Ellerman @ 2021-09-27 13:11 UTC (permalink / raw)
To: Christophe Leroy, Andrew Morton, arnd
Cc: Christophe Leroy, linux-kernel, linux-mm, linux-s390,
linuxppc-dev, linux-arch, Gerald Schaefer
Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Commit 7a5da02de8d6 ("locking/lockdep: check for freed initmem in
> static_obj()") added arch_is_kernel_initmem_freed() which is supposed
> to report whether an object is part of already freed init memory.
>
> For the time being, the generic version of arch_is_kernel_initmem_freed()
> always reports 'false', allthough free_initmem() is generically called
> on all architectures.
>
> Therefore, change the generic version of arch_is_kernel_initmem_freed()
> to check whether free_initmem() has been called. If so, then check
> if a given address falls into init memory.
>
> In order to use function init_section_contains(), the fonction is
> moved at the end of asm-generic/section.h
>
> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
> include/asm-generic/sections.h | 31 +++++++++++++++++--------------
> 1 file changed, 17 insertions(+), 14 deletions(-)
>
> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
> index d16302d3eb59..d1e5bb2c6b72 100644
> --- a/include/asm-generic/sections.h
> +++ b/include/asm-generic/sections.h
> @@ -172,4 +158,21 @@ static inline bool is_kernel_rodata(unsigned long addr)
> addr < (unsigned long)__end_rodata;
> }
>
> +/*
> + * Check if an address is part of freed initmem. This is needed on architectures
> + * with virt == phys kernel mapping, for code that wants to check if an address
> + * is part of a static object within [_stext, _end]. After initmem is freed,
> + * memory can be allocated from it, and such allocations would then have
> + * addresses within the range [_stext, _end].
> + */
> +#ifndef arch_is_kernel_initmem_freed
> +static inline int arch_is_kernel_initmem_freed(unsigned long addr)
> +{
> + if (system_state < SYSTEM_RUNNING)
> + return 0;
> +
> + return init_section_contains((void *)addr, 1);
> +}
> +#endif
This will return an incorrect result for a short period during boot
won't it?
See init/main.c:
static int __ref kernel_init(void *unused)
{
...
free_initmem(); <- memory is freed here
mark_readonly();
/*
* Kernel mappings are now finalized - update the userspace page-table
* to finalize PTI.
*/
pti_finalize();
system_state = SYSTEM_RUNNING;
After free_initmem() we have address ranges that are now freed initmem,
but arch_is_kernel_initmem_freed() continues to return 0 (false) for all
addresses, until we update system_state.
Possibly that doesn't matter for any of the current callers, but it
seems pretty dicey to me.
cheers
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH 1/3] mm: Make generic arch_is_kernel_initmem_freed() do what it says
2021-09-27 13:11 ` [PATCH 1/3] mm: Make generic arch_is_kernel_initmem_freed() do what it says Michael Ellerman
@ 2021-09-27 13:51 ` Christophe Leroy
0 siblings, 0 replies; 5+ messages in thread
From: Christophe Leroy @ 2021-09-27 13:51 UTC (permalink / raw)
To: Michael Ellerman, Andrew Morton, arnd
Cc: linux-kernel, linux-mm, linux-s390, linuxppc-dev, linux-arch,
Gerald Schaefer
Le 27/09/2021 à 15:11, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>> Commit 7a5da02de8d6 ("locking/lockdep: check for freed initmem in
>> static_obj()") added arch_is_kernel_initmem_freed() which is supposed
>> to report whether an object is part of already freed init memory.
>>
>> For the time being, the generic version of arch_is_kernel_initmem_freed()
>> always reports 'false', allthough free_initmem() is generically called
>> on all architectures.
>>
>> Therefore, change the generic version of arch_is_kernel_initmem_freed()
>> to check whether free_initmem() has been called. If so, then check
>> if a given address falls into init memory.
>>
>> In order to use function init_section_contains(), the fonction is
>> moved at the end of asm-generic/section.h
>>
>> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> ---
>> include/asm-generic/sections.h | 31 +++++++++++++++++--------------
>> 1 file changed, 17 insertions(+), 14 deletions(-)
>>
>> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
>> index d16302d3eb59..d1e5bb2c6b72 100644
>> --- a/include/asm-generic/sections.h
>> +++ b/include/asm-generic/sections.h
>> @@ -172,4 +158,21 @@ static inline bool is_kernel_rodata(unsigned long addr)
>> addr < (unsigned long)__end_rodata;
>> }
>>
>> +/*
>> + * Check if an address is part of freed initmem. This is needed on architectures
>> + * with virt == phys kernel mapping, for code that wants to check if an address
>> + * is part of a static object within [_stext, _end]. After initmem is freed,
>> + * memory can be allocated from it, and such allocations would then have
>> + * addresses within the range [_stext, _end].
>> + */
>> +#ifndef arch_is_kernel_initmem_freed
>> +static inline int arch_is_kernel_initmem_freed(unsigned long addr)
>> +{
>> + if (system_state < SYSTEM_RUNNING)
>> + return 0;
>> +
>> + return init_section_contains((void *)addr, 1);
>> +}
>> +#endif
>
> This will return an incorrect result for a short period during boot
> won't it?
>
> See init/main.c:
>
> static int __ref kernel_init(void *unused)
> {
> ...
> free_initmem(); <- memory is freed here
> mark_readonly();
>
> /*
> * Kernel mappings are now finalized - update the userspace page-table
> * to finalize PTI.
> */
> pti_finalize();
>
> system_state = SYSTEM_RUNNING;
>
>
> After free_initmem() we have address ranges that are now freed initmem,
> but arch_is_kernel_initmem_freed() continues to return 0 (false) for all
> addresses, until we update system_state.
>
> Possibly that doesn't matter for any of the current callers, but it
> seems pretty dicey to me.
>
Yes I saw it but as function core_kernel_text() uses that criteria for
deciding whether a given init text address is valid or not, I thought it
was just ok.
Should we add an intermediate state called for exemple
SYSTEM_FREEING_INIT just before SYSTEM_RUNNING ?
Christophe
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-09-24 13:48 ` [PATCH 3/3] s390: " Christophe Leroy
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