linux-stable.git/arch/powerpc/lib/code-patching.c, branch v5.16.2

powerpc/lib: Add helper to check if offset is within conditional branch range

2021-10-07T07:52:33+00:00

Add a helper to check if a given offset is within the branch range for a
powerpc conditional branch instruction, and update some sites to use the
new helper.

Signed-off-by: Naveen N. Rao 
Reviewed-by: Christophe Leroy 
Acked-by: Song Liu 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/442b69a34ced32ca346a0d9a855f3f6cfdbbbd41.1633464148.git.naveen.n.rao@linux.vnet.ibm.com

powerpc/lib/code-patching: Set up Strict RWX patching earlier

2021-06-21T11:13:20+00:00

setup_text_poke_area() is a late init call so it runs before
mark_rodata_ro() and after the init calls. This lets all the init code
patching simply write to their locations. In the future, kprobes is
going to allocate its instruction pages RO which means they will need
setup_text__poke_area() to have been already called for their code
patching. However, init_kprobes() (which allocates and patches some
instruction pages) is an early init call so it happens before
setup_text__poke_area().

start_kernel() calls poking_init() before any of the init calls. On
powerpc, poking_init() is currently a nop. setup_text_poke_area() relies
on kernel virtual memory, cpu hotplug and per_cpu_areas being setup.
setup_per_cpu_areas(), boot_cpu_hotplug_init() and mm_init() are called
before poking_init().

Turn setup_text_poke_area() into poking_init().

Signed-off-by: Jordan Niethe 
Reviewed-by: Christophe Leroy 
Reviewed-by: Russell Currey 
[mpe: Fold in missing prototype for poking_init() from lkp]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210609013431.9805-3-jniethe5@gmail.com

powerpc: Don't use 'struct ppc_inst' to reference instruction location

2021-06-16T14:09:00+00:00

'struct ppc_inst' is an internal representation of an instruction, but
in-memory instructions are and will remain a table of 'u32' forever.

Replace all 'struct ppc_inst *' used for locating an instruction in
memory by 'u32 *'. This removes a lot of undue casts to 'struct
ppc_inst *'.

It also helps locating ab-use of 'struct ppc_inst' dereference.

Signed-off-by: Christophe Leroy 
[mpe: Fix ppc_inst_next(), use u32 instead of unsigned int]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/7062722b087228e42cbd896e39bfdf526d6a340a.1621516826.git.christophe.leroy@csgroup.eu

powerpc/lib/code-patching: Don't use struct 'ppc_inst' for runnable code in tests.

2021-06-16T14:07:51+00:00

'struct ppc_inst' is meant to represent an instruction internally, it
is not meant to dereference code in memory.

For testing code patching, use patch_instruction() to properly
write into memory the code to be tested.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/d8425fb42a4adebc35b7509f121817eeb02fac31.1621516826.git.christophe.leroy@csgroup.eu

powerpc/lib/code-patching: Make instr_is_branch_to_addr() static

2021-06-16T13:35:57+00:00

instr_is_branch_to_addr() is only used in code-patching.c

Make it static.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/5f6b9c8c83170ed310953eac2f5b14539bfc964a.1621516826.git.christophe.leroy@csgroup.eu

powerpc: Do not dereference code as 'struct ppc_inst' (uprobe, code-patching, feature-fixups)

2021-06-16T13:35:57+00:00

'struct ppc_inst' is an internal structure to represent an instruction,
it is not directly the representation of that instruction in text code.
It is not meant to map and dereference code.

Dereferencing code directly through 'struct ppc_inst' has two main issues:
- On powerpc, structs are expected to be 8 bytes aligned while code is
spread every 4 byte.
- Should a non prefixed instruction lie at the end of the page and the
following page not be mapped, it would generate a page fault.

In-memory code must be accessed with ppc_inst_read().

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/c9a1201dd0a66b4a0f91f0fb46d9385cbf030feb.1621516826.git.christophe.leroy@csgroup.eu

powerpc/inst: ppc_inst_as_u64() becomes ppc_inst_as_ulong()

2021-04-21T12:52:32+00:00

In order to simplify use on PPC32, change ppc_inst_as_u64()
into ppc_inst_as_ulong() that returns the 32 bits instruction
on PPC32.

Will be used when porting OPTPROBES to PPC32.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/22cadf29620664b600b82026d2a72b8b23351777.1618927318.git.christophe.leroy@csgroup.eu

powerpc/lib: Don't use __put_user_asm_goto() outside of uaccess.h

2021-03-26T12:19:42+00:00

__put_user_asm_goto() is internal to uaccess.h

Use __put_kernel_nofault() instead. The generated code is identical.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/3e32c4f0361933909368b68f5ee569e5de661c1b.1615398498.git.christophe.leroy@csgroup.eu

powerpc/uaccess: Switch __patch_instruction() to __put_user_asm_goto()

2020-09-15T12:13:32+00:00

__patch_instruction() is the only user of __put_user_asm() outside
of asm/uaccess.h

Switch to the new __put_user_asm_goto() to enable retirement of
__put_user_asm() in a later patch.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/b9745b122f4a9ae72cef445c61320022ab8b77b7.1599216721.git.christophe.leroy@csgroup.eu

powerpc/lib: Prepare code-patching for modules allocated outside vmalloc space

2020-07-26T14:01:30+00:00

Use is_vmalloc_or_module_addr() instead of is_vmalloc_addr()

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/7d884db0e5a6f521331639d8c0f13e520d5a4fef.1593428200.git.christophe.leroy@csgroup.eu