kernel/linux.git/arch/powerpc/include/asm/sections.h, branch v6.1.168

powerpc/vmlinux.lds: Add an explicit symbol for the SRWX boundary

2022-09-26T10:58:16+00:00

Currently __init_begin is used as the boundary for strict RWX between executable/read-only text and data, and non-executable (after boot) code and data. But that's a little subtle, so add an explicit symbol to document that the SRWX boundary lies there, and add a comment making it clear that __init_begin must also begin there. Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220916131422.318752-2-mpe@ellerman.id.au

powerpc/64: Remove unused prom_init_toc symbols

2022-09-26T10:58:16+00:00

Commit 24d33ac5b8ff ("powerpc/64s: Make prom_init require RELOCATABLE") made prom_init depend on CONFIG_RELOCATABLE. But it missed cleaning up a case in the linker script for RELOCATABLE=n, and associated symbols. Remove them now. Fixes: 24d33ac5b8ff ("powerpc/64s: Make prom_init require RELOCATABLE") Reported-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220920131157.1032707-1-mpe@ellerman.id.au

powerpc: Move patch sites out of asm-prototypes.h

2022-08-26T01:02:20+00:00

The definitions for the patch sites etc. don't belong in asm-prototypes.h, they are not EXPORT'ed asm symbols. Move them into sections.h which is traditionally used for asm symbols. Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220818050659.187181-1-mpe@ellerman.id.au

asm-generic: Refactor dereference_[kernel]_function_descriptor()

2022-02-16T12:25:11+00:00

dereference_function_descriptor() and dereference_kernel_function_descriptor() are identical on the three architectures implementing them. Make them common and put them out-of-line in kernel/extable.c which is one of the users and has similar type of functions. Signed-off-by: Christophe Leroy Reviewed-by: Kees Cook Reviewed-by: Arnd Bergmann Acked-by: Helge Deller Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/449db09b2eba57f4ab05f80102a67d8675bc8bcd.1644928018.git.christophe.leroy@csgroup.eu

asm-generic: Define 'func_desc_t' to commonly describe function descriptors

2022-02-16T12:25:11+00:00

We have three architectures using function descriptors, each with its own type and name. Add a common typedef that can be used in generic code. Also add a stub typedef for architecture without function descriptors, to avoid a forest of #ifdefs. It replaces the similar 'func_desc_t' previously defined in arch/powerpc/kernel/module_64.c Signed-off-by: Christophe Leroy Reviewed-by: Kees Cook Acked-by: Arnd Bergmann Acked-by: Helge Deller Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/f1f91b142b3c1082bdc1586ce71c9bac1e75213c.1644928018.git.christophe.leroy@csgroup.eu

asm-generic: Define CONFIG_HAVE_FUNCTION_DESCRIPTORS

2022-02-16T12:25:11+00:00

Replace HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR by a config option named CONFIG_HAVE_FUNCTION_DESCRIPTORS and use it instead of 'dereference_function_descriptor' macro to know whether an arch has function descriptors. To limit churn in one of the following patches, use an #ifdef/#else construct with empty first part instead of an #ifndef in asm-generic/sections.h On powerpc, make sure the config option matches the ABI used by the compiler with a BUILD_BUG_ON() and add missing _CALL_ELF=2 when calling 'sparse' so that sparse sees the same piece of code as GCC. And include a helper to check whether an arch has function descriptors or not : have_function_descriptors() Signed-off-by: Christophe Leroy Reviewed-by: Kees Cook Reviewed-by: Nicholas Piggin Acked-by: Helge Deller Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/4a0f11fb0ea74a3197bc44dd7ba25e53a24fd03d.1644928018.git.christophe.leroy@csgroup.eu

powerpc: Use 'struct func_desc' instead of 'struct ppc64_opd_entry'

2022-02-16T12:25:10+00:00

'struct ppc64_opd_entry' is somehow redundant with 'struct func_desc', the later is more correct/complete as it includes the third field which is unused. So use 'struct func_desc' instead of 'struct ppc64_opd_entry' Signed-off-by: Christophe Leroy Reviewed-by: Kees Cook Reviewed-by: Daniel Axtens Reviewed-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/34e76bac6cbe95a63ecd37df69fb7feb93b0ea7c.1644928018.git.christophe.leroy@csgroup.eu

powerpc/toc: Future proof kernel toc

2021-12-23T11:35:01+00:00

This patch future-proofs the kernel against linker changes that might put the toc pointer at some location other than .got+0x8000, by replacing __toc_start+0x8000 with .TOC. throughout. If the kernel's idea of the toc pointer doesn't agree with the linker, bad things happen. prom_init.c code relocating its toc is also changed so that a symbolic __prom_init_toc_start toc-pointer relative address is calculated rather than assuming that it is always at toc-pointer - 0x8000. The length calculations loading values from the toc are also avoided. It's a little incestuous to do that with unreloc_toc picking up adjusted values (which is fine in practice, they both adjust by the same amount if all goes well). I've also changed the way .got is aligned in vmlinux.lds and zImage.lds, mostly so that dumping out section info by objdump or readelf plainly shows the alignment is 256. This linker script feature was added 2005-09-27, available in FSF binutils releases from 2.17 onwards. Should be safe to use in the kernel, I think. Finally, put *(.got) before the prom_init.o entry which only needs *(.toc), so that the GOT header goes in the correct place. I don't believe this makes any difference for the kernel as it would for dynamic objects being loaded by ld.so. That change is just to stop lusers who blindly copy kernel scripts being led astray. Of course, this change needs the prom_init.c changes. Some notes on .toc and .got. .toc is a compiler generated section of addresses. .got is a linker generated section of addresses, generally built when the linker sees R_*_*GOT* relocations. In the case of powerpc64 ld.bfd, there are multiple generated .got sections, one per input object file. So you can somewhat reasonably write in a linker script an input section statement like *prom_init.o(.got .toc) to mean "the .got and .toc section for files matching *prom_init.o". On other architectures that doesn't make sense, because the linker generally has just one .got section. Even on powerpc64, note well that the GOT entries for prom_init.o may be merged with GOT entries from other objects. That means that if prom_init.o references, say, _end via some GOT relocation, and some other object also references _end via a GOT relocation, the GOT entry for _end may be in the range __prom_init_toc_start to __prom_init_toc_end and if the kernel does something special to GOT/TOC entries in that range then the value of _end as seen by objects other than prom_init.o will be affected. On the other hand the GOT entry for _end may not be in the range __prom_init_toc_start to __prom_init_toc_end. Which way it turns out is deterministic but a detail of linker operation that should not be relied on. A feature of ld.bfd is that input .toc (and .got) sections matching one linker input section statement may be sorted, to put entries used by small-model code first, near the toc base. This is why scripts for powerpc64 normally use *(.got .toc) rather than *(.got) *(.toc), since the first form allows more freedom to sort. Another feature of ld.bfd is that indirect addressing sequences using the GOT/TOC may be edited by the linker to relative addressing. In many cases relative addressing would be emitted by gcc for -mcmodel=medium if you appropriately decorate variable declarations with non-default visibility. The original patch is here: https://lore.kernel.org/linuxppc-dev/20210310034813.GM6042@bubble.grove.modra.org/ Signed-off-by: Alan Modra [aik: removed non-relocatable which is gone in 24d33ac5b8ffb] [aik: added <=2.24 check] [aik: because of llvm-as, kernel_toc_addr() uses "mr" instead of global register variable] Signed-off-by: Alexey Kardashevskiy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211221055904.555763-2-aik@ozlabs.ru

powerpc: use generic version of arch_is_kernel_initmem_freed()

2021-11-06T20:30:38+00:00

The generic version of arch_is_kernel_initmem_freed() now does the same as powerpc version. Remove the powerpc version. Link: https://lkml.kernel.org/r/c53764eb45d41491e2b21da2e7812239897dbebb.1633001016.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy Cc: Kefeng Wang Cc: Benjamin Herrenschmidt Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Paul Mackerras Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

powerpc: Remove in_kernel_text()

2021-08-10T13:14:55+00:00

Last user of in_kernel_text() stopped using in with commit 549e8152de80 ("powerpc: Make the 64-bit kernel as a position-independent executable"). Generic function is_kernel_text() does the same. So remote it. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/2a3a5b6f8cc0ef4e854d7b764f66aa8d2ee270d2.1624813698.git.christophe.leroy@csgroup.eu