| Message ID | 1d40783e676e07858be97d881f449ee7ea8adfb1.1633001016.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,1/4] mm: Create a new system state and fix core_kernel_text() | expand |
> #ifdef __KERNEL__ > +/* > + * Check if an address is part of freed initmem. 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 int arch_is_kernel_initmem_freed(unsigned long addr) > +{ > + if (system_state < SYSTEM_FREEING_INITMEM) > + return 0; > + > + return init_section_contains((void *)addr, 1); Is init_section_contains sufficient here? include/asm-generic/sections.h says: * [__init_begin, __init_end]: contains .init.* sections, but .init.text.* * may be out of this range on some architectures. * [_sinittext, _einittext]: contains .init.text.* sections init_section_contains only checks __init_*: static inline bool init_section_contains(void *virt, size_t size) { return memory_contains(__init_begin, __init_end, virt, size); } Do we need to check against _sinittext and _einittext? Your proposed generic code will work for powerpc and s390 because those archs only test against __init_* anyway. I don't know if any platform actually does place .init.text outside of __init_begin=>__init_end, but the comment seems to suggest that they could. Kind regards, Daniel
On Fri, 01 Oct 2021 17:14:41 +1000 Daniel Axtens <dja@axtens.net> wrote: > > #ifdef __KERNEL__ > > +/* > > + * Check if an address is part of freed initmem. 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 int arch_is_kernel_initmem_freed(unsigned long addr) > > +{ > > + if (system_state < SYSTEM_FREEING_INITMEM) > > + return 0; > > + > > + return init_section_contains((void *)addr, 1); > > Is init_section_contains sufficient here? > > include/asm-generic/sections.h says: > * [__init_begin, __init_end]: contains .init.* sections, but .init.text.* > * may be out of this range on some architectures. > * [_sinittext, _einittext]: contains .init.text.* sections > > init_section_contains only checks __init_*: > static inline bool init_section_contains(void *virt, size_t size) > { > return memory_contains(__init_begin, __init_end, virt, size); > } > > Do we need to check against _sinittext and _einittext? > > Your proposed generic code will work for powerpc and s390 because those > archs only test against __init_* anyway. I don't know if any platform > actually does place .init.text outside of __init_begin=>__init_end, but > the comment seems to suggest that they could. > Christophe?
Le 04/11/2021 à 22:44, Andrew Morton a écrit : > On Fri, 01 Oct 2021 17:14:41 +1000 Daniel Axtens <dja@axtens.net> wrote: > >>> #ifdef __KERNEL__ >>> +/* >>> + * Check if an address is part of freed initmem. 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 int arch_is_kernel_initmem_freed(unsigned long addr) >>> +{ >>> + if (system_state < SYSTEM_FREEING_INITMEM) >>> + return 0; >>> + >>> + return init_section_contains((void *)addr, 1); >> >> Is init_section_contains sufficient here? >> >> include/asm-generic/sections.h says: >> * [__init_begin, __init_end]: contains .init.* sections, but .init.text.* >> * may be out of this range on some architectures. >> * [_sinittext, _einittext]: contains .init.text.* sections >> >> init_section_contains only checks __init_*: >> static inline bool init_section_contains(void *virt, size_t size) >> { >> return memory_contains(__init_begin, __init_end, virt, size); >> } >> >> Do we need to check against _sinittext and _einittext? >> >> Your proposed generic code will work for powerpc and s390 because those >> archs only test against __init_* anyway. I don't know if any platform >> actually does place .init.text outside of __init_begin=>__init_end, but >> the comment seems to suggest that they could. >> > > Christophe? > Sorry for answering late. I've been thorugh free_initmem() in each architecture. The only sections involved in the freeing actions are [__init_begin, __init_end], so I think checking against __init_being, __init_end is enough. If some architecture has init text outside of this section, then it is not freed hence not necessary to check. Christophe
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h index d16302d3eb59..596ab2092289 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 diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index bf1c00c881e4..8e118caf835e 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -788,6 +788,21 @@ static int very_verbose(struct lock_class *class) * Is this the address of a static object: */ #ifdef __KERNEL__ +/* + * Check if an address is part of freed initmem. 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 int arch_is_kernel_initmem_freed(unsigned long addr) +{ + if (system_state < SYSTEM_FREEING_INITMEM) + return 0; + + return init_section_contains((void *)addr, 1); +} +#endif + static int static_obj(const void *obj) { unsigned long start = (unsigned long) &_stext,
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. To ease the use of system_state, move it out of line into its only caller which is lockdep.c Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- v3: Move it out of sections.h into lockdep.c and fix the comment. v2: Change to using the new SYSTEM_FREEING_INITMEM state Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- include/asm-generic/sections.h | 14 -------------- kernel/locking/lockdep.c | 15 +++++++++++++++ 2 files changed, 15 insertions(+), 14 deletions(-)