linux.git/arch/powerpc/kernel/module_64.c, branch v5.10

maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault

2020-06-17T17:57:41+00:00

Better describe what these functions do.

Suggested-by: Linus Torvalds 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Linus Torvalds

powerpc/module_64: Use special stub for _mcount() with -mprofile-kernel

2020-06-02T10:59:16+00:00

Since commit c55d7b5e64265f ("powerpc: Remove STRICT_KERNEL_RWX
incompatibility with RELOCATABLE"), powerpc kernels with
-mprofile-kernel can crash in certain scenarios with a trace like below:

    BUG: Unable to handle kernel instruction fetch (NULL pointer?)
    Faulting instruction address: 0x00000000
    Oops: Kernel access of bad area, sig: 11 [#1]
    LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA PowerNV
    
    NIP [0000000000000000] 0x0
    LR [c0080000102c0048] ext4_iomap_end+0x8/0x30 [ext4]
    Call Trace:
     iomap_apply+0x20c/0x920 (unreliable)
     iomap_bmap+0xfc/0x160
     ext4_bmap+0xa4/0x180 [ext4]
     bmap+0x4c/0x80
     jbd2_journal_init_inode+0x44/0x1a0 [jbd2]
     ext4_load_journal+0x440/0x860 [ext4]
     ext4_fill_super+0x342c/0x3ab0 [ext4]
     mount_bdev+0x25c/0x290
     ext4_mount+0x28/0x50 [ext4]
     legacy_get_tree+0x4c/0xb0
     vfs_get_tree+0x4c/0x130
     do_mount+0xa18/0xc50
     sys_mount+0x158/0x180
     system_call+0x5c/0x68

The NIP points to NULL, or a random location (data even), while the LR
always points to the LEP of a function (with an offset of 8), indicating
that something went wrong with ftrace. However, ftrace is not
necessarily active when such crashes occur.

The kernel OOPS sometimes follows a warning from ftrace indicating that
some module functions could not be patched with a nop. Other times, if a
module is loaded early during boot, instruction patching can fail due to
a separate bug, but the error is not reported due to missing error
reporting.

In all the above cases when instruction patching fails, ftrace will be
disabled but certain kernel module functions will be left with default
calls to _mcount(). This is not a problem with ELFv1. However, with
-mprofile-kernel, the default stub is problematic since it depends on a
valid module TOC in r2. If the kernel (or a different module) calls into
a function that does not use the TOC, the function won't have a prologue
to setup the module TOC. When that function calls into _mcount(), we
will end up in the relocation stub that will use the previous TOC, and
end up trying to jump into a random location. From the above trace:

	iomap_apply+0x20c/0x920 [kernel TOC]
			|
			V
	ext4_iomap_end+0x8/0x30 [no GEP == kernel TOC]
			|
			V
		_mcount() stub
	[uses kernel TOC -> random entry]

To address this, let's change over to using the special stub that is
used for ftrace_[regs_]caller() for _mcount(). This ensures that we are
not dependent on a valid module TOC in r2 for default _mcount()
handling.

Reported-by: Qian Cai 
Signed-off-by: Naveen N. Rao 
Tested-by: Qian Cai 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/8affd4298d22099bbd82544fab8185700a6222b1.1587488954.git.naveen.n.rao@linux.vnet.ibm.com

powerpc/module_64: Simplify check for -mprofile-kernel ftrace relocations

2020-06-02T10:59:15+00:00

For -mprofile-kernel, we need special handling when generating stubs for
ftrace calls such as _mcount(). To faciliate this, we check if a
R_PPC64_REL24 relocation is for a symbol named "_mcount()" along with
also checking the instruction sequence. The latter is not really
required since "_mcount()" is an exported symbol and kernel modules
cannot use it. As such, drop the additional checking and simplify the
code. This helps unify stub creation for ftrace stubs with
-mprofile-kernel and aids in code reuse.

Also rename is_mprofile_mcount_callsite() to is_mprofile_ftrace_call()
to reflect the checking being done.

Signed-off-by: Naveen N. Rao 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/7d9c316adfa1fb787ad268bb4691e7e4059ff2d5.1587488954.git.naveen.n.rao@linux.vnet.ibm.com

powerpc/module_64: Consolidate ftrace code

2020-06-02T10:59:15+00:00

module_trampoline_target() is only used by ftrace. Move the prototype
within the appropriate #ifdef in the header. Also, move the function
body to the end of module_64.c so as to consolidate all ftrace code in
one place.

No functional changes.

Signed-off-by: Naveen N. Rao 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/2527351f65c53c5866068ae130dc34c5d4ee8ad9.1587488954.git.naveen.n.rao@linux.vnet.ibm.com

powerpc: Use a macro for creating instructions from u32s

2020-05-18T14:10:36+00:00

In preparation for instructions having a more complex data type start
using a macro, ppc_inst(), for making an instruction out of a u32.  A
macro is used so that instructions can be used as initializer elements.
Currently this does nothing, but it will allow for creating a data type
that can represent prefixed instructions.

Signed-off-by: Jordan Niethe 
[mpe: Change include guard to _ASM_POWERPC_INST_H]
Signed-off-by: Michael Ellerman 
Reviewed-by: Alistair Popple 
Link: https://lore.kernel.org/r/20200506034050.24806-7-jniethe5@gmail.com

powerpc: module_[32|64].c: replace swap function with built-in one

2020-05-11T13:15:14+00:00

Replace relaswap with built-in one, because relaswap
does a simple byte to byte swap.

Since Spectre mitigations have made indirect function calls more
expensive, and the default simple byte copies swap is implemented
without them, an "optimized" custom swap function is now
a waste of time as well as code.

Signed-off-by: Andrey Abramov 
Reviewed-by: George Spelvin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/994931554238042@iva8-b333b7f98ab0.qloud-c.yandex.net

Merge tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2019-07-13T23:08:36+00:00

Pull powerpc updates from Michael Ellerman:
"Notable changes:

- Removal of the NPU DMA code, used by the out-of-tree Nvidia driver,
as well as some other functions only used by drivers that haven't
(yet?) made it upstream.

- A fix for a bug in our handling of hardware watchpoints (eg. perf
record -e mem: ...) which could lead to register corruption and
kernel crashes.

- Enable HAVE_ARCH_HUGE_VMAP, which allows us to use large pages for
vmalloc when using the Radix MMU.

- A large but incremental rewrite of our exception handling code to
use gas macros rather than multiple levels of nested CPP macros.

And the usual small fixes, cleanups and improvements.

Thanks to: Alastair D'Silva, Alexey Kardashevskiy, Andreas Schwab,
Aneesh Kumar K.V, Anju T Sudhakar, Anton Blanchard, Arnd Bergmann,
Athira Rajeev, Cédric Le Goater, Christian Lamparter, Christophe
Leroy, Christophe Lombard, Christoph Hellwig, Daniel Axtens, Denis
Efremov, Enrico Weigelt, Frederic Barrat, Gautham R. Shenoy, Geert
Uytterhoeven, Geliang Tang, Gen Zhang, Greg Kroah-Hartman, Greg Kurz,
Gustavo Romero, Krzysztof Kozlowski, Madhavan Srinivasan, Masahiro
Yamada, Mathieu Malaterre, Michael Neuling, Nathan Lynch, Naveen N.
Rao, Nicholas Piggin, Nishad Kamdar, Oliver O'Halloran, Qian Cai, Ravi
Bangoria, Sachin Sant, Sam Bobroff, Satheesh Rajendran, Segher
Boessenkool, Shaokun Zhang, Shawn Anastasio, Stewart Smith, Suraj
Jitindar Singh, Thiago Jung Bauermann, YueHaibing"

* tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (163 commits)
powerpc/powernv/idle: Fix restore of SPRN_LDBAR for POWER9 stop state.
powerpc/eeh: Handle hugepages in ioremap space
ocxl: Update for AFU descriptor template version 1.1
powerpc/boot: pass CONFIG options in a simpler and more robust way
powerpc/boot: add {get, put}_unaligned_be32 to xz_config.h
powerpc/irq: Don't WARN continuously in arch_local_irq_restore()
powerpc/module64: Use symbolic instructions names.
powerpc/module32: Use symbolic instructions names.
powerpc: Move PPC_HA() PPC_HI() and PPC_LO() to ppc-opcode.h
powerpc/module64: Fix comment in R_PPC64_ENTRY handling
powerpc/boot: Add lzo support for uImage
powerpc/boot: Add lzma support for uImage
powerpc/boot: don't force gzipped uImage
powerpc/8xx: Add microcode patch to move SMC parameter RAM.
powerpc/8xx: Use IO accessors in microcode programming.
powerpc/8xx: replace #ifdefs by IS_ENABLED() in microcode.c
powerpc/8xx: refactor programming of microcode CPM params.
powerpc/8xx: refactor printing of microcode patch name.
powerpc/8xx: Refactor microcode write
powerpc/8xx: refactor writing of CPM microcode arrays
...

powerpc/module64: Use symbolic instructions names.

2019-07-05T14:29:50+00:00

To increase readability/maintainability, replace hard coded
instructions values by symbolic names.

Signed-off-by: Christophe Leroy 
[mpe: Fix R_PPC64_ENTRY case, the addi reads from r2 not r12]
Signed-off-by: Michael Ellerman

powerpc: Move PPC_HA() PPC_HI() and PPC_LO() to ppc-opcode.h

2019-07-05T14:29:50+00:00

PPC_HA() PPC_HI() and PPC_LO() macros are nice macros. Move them
from module64.c to ppc-opcode.h in order to use them in other places.

Signed-off-by: Christophe Leroy 
[mpe: Clean up formatting in new code, drop duplicates in ftrace.c]
Signed-off-by: Michael Ellerman

powerpc/module64: Fix comment in R_PPC64_ENTRY handling

2019-07-05T14:29:50+00:00

The comment here is wrong, the addi reads from r2 not r12. The code is
correct, 0x38420000 = addi r2,r2,0.

Fixes: a61674bdfc7c ("powerpc/module: Handle R_PPC64_ENTRY relocations")
Signed-off-by: Michael Ellerman