linux-stable.git/arch/powerpc/kernel/optprobes.c, branch linux-rolling-stable

asm-generic: introduce text-patching.h

2024-11-07T22:25:15+00:00

Several architectures support text patching, but they name the header
files that declare patching functions differently.

Make all such headers consistently named text-patching.h and add an empty
header in asm-generic for architectures that do not support text patching.

Link: https://lkml.kernel.org/r/20241023162711.2579610-4-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) 
Reviewed-by: Christoph Hellwig 
Acked-by: Geert Uytterhoeven  # m68k
Acked-by: Arnd Bergmann 
Reviewed-by: Luis Chamberlain 
Tested-by: kdevops 
Cc: Andreas Larsson 
Cc: Andy Lutomirski 
Cc: Ard Biesheuvel 
Cc: Borislav Petkov (AMD) 
Cc: Brian Cain 
Cc: Catalin Marinas 
Cc: Christophe Leroy 
Cc: Dave Hansen 
Cc: Dinh Nguyen 
Cc: Guo Ren 
Cc: Helge Deller 
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: Johannes Berg 
Cc: John Paul Adrian Glaubitz 
Cc: Kent Overstreet 
Cc: Liam R. Howlett 
Cc: Mark Rutland 
Cc: Masami Hiramatsu (Google) 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Oleg Nesterov 
Cc: Palmer Dabbelt 
Cc: Peter Zijlstra 
Cc: Richard Weinberger 
Cc: Russell King 
Cc: Song Liu 
Cc: Stafford Horne 
Cc: Steven Rostedt (Google) 
Cc: Suren Baghdasaryan 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Uladzislau Rezki (Sony) 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

powerpc: Replace kretprobe code with rethook on powerpc

2024-09-05T12:25:36+00:00

This is an adaptation of commit f3a112c0c40d ("x86,rethook,kprobes:
Replace kretprobe with rethook on x86") to powerpc.

Rethook follows the existing kretprobe implementation, but separates
it from kprobes so that it can be used by fprobe (ftrace-based
function entry/exit probes). As such, this patch also enables fprobe
to work on powerpc. The only other change compared to the existing
kretprobe implementation is doing the return address fixup in
arch_rethook_fixup_return().

Reference to other archs:
commit b57c2f124098 ("riscv: add riscv rethook implementation")
commit 7b0a096436c2 ("LoongArch: Replace kretprobe with rethook")

Note:
=====

In future, rethook will be only for kretprobe, and kretprobe
will be replaced by fprobe.

https://lore.kernel.org/all/172000134410.63468.13742222887213469474.stgit@devnote2/

We will	adapt the above	implementation for powerpc once its upstream.
Until then, we can have	this implementation of rethook to serve
current	kretprobe usecases.

Reviewed-by: Naveen Rao 
Signed-off-by: Abhishek Dubey 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20240830113131.7597-1-adubey@linux.ibm.com

powerpc/kprobes: Have optimized_callback() use preempt_enable()

2022-11-24T12:31:49+00:00

Similar to x86 commit 2e62024c265aa6 ("kprobes/x86: Use preempt_enable()
in optimized_callback()"), change powerpc optprobes to use
preempt_enable() rather than preempt_enable_no_resched() since powerpc
also removed irq disabling for optprobes in commit f72180cc93a2c6
("powerpc/kprobes: Do not disable interrupts for optprobes and
kprobes_on_ftrace").

Reported-by: Nicholas Piggin 
Signed-off-by: Naveen N. Rao 
Reviewed-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/1885bab182626c33d9bf6421f430abf924c521a5.1666262278.git.naveen.n.rao@linux.vnet.ibm.com

powerpc/inst: Define ppc_inst_t as u32 on PPC32

2021-12-09T11:41:21+00:00

Unlike PPC64 ABI, PPC32 uses the stack to pass a parameter defined
as a struct, even when the struct has a single simple element.

To avoid that, define ppc_inst_t as u32 on PPC32.

Keep it as 'struct ppc_inst' when __CHECKER__ is defined so that
sparse can perform type checking.

Also revert commit 511eea5e2ccd ("powerpc/kprobes: Fix Oops by passing
ppc_inst as a pointer to emulate_step() on ppc32") as now the
instruction to be emulated is passed as a register to emulate_step().

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/c6d0c46f598f76ad0b0a88bc0d84773bd921b17c.1638208156.git.christophe.leroy@csgroup.eu

powerpc/inst: Define ppc_inst_t

2021-12-09T11:41:21+00:00

In order to stop using 'struct ppc_inst' on PPC32,
define a ppc_inst_t typedef.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/fe5baa2c66fea9db05a8b300b3e8d2880a42596c.1638208156.git.christophe.leroy@csgroup.eu

kprobes: treewide: Make it harder to refer kretprobe_trampoline directly

2021-10-01T01:24:06+00:00

Since now there is kretprobe_trampoline_addr() for referring the
address of kretprobe trampoline code, we don't need to access
kretprobe_trampoline directly.

Make it harder to refer by renaming it to __kretprobe_trampoline().

Link: https://lkml.kernel.org/r/163163045446.489837.14510577516938803097.stgit@devnote2

Suggested-by: Ingo Molnar 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware)

kprobes: treewide: Use 'kprobe_opcode_t *' for the code address in get_optimized_kprobe()

2021-10-01T01:24:05+00:00

Since get_optimized_kprobe() is only used inside kprobes,
it doesn't need to use 'unsigned long' type for 'addr' parameter.
Make it use 'kprobe_opcode_t *' for the 'addr' parameter and
subsequent call of arch_within_optimized_kprobe() also should use
'kprobe_opcode_t *'.

Note that MAX_OPTIMIZED_LENGTH and RELATIVEJUMP_SIZE are defined
by byte-size, but the size of 'kprobe_opcode_t' depends on the
architecture. Therefore, we must be careful when calculating
addresses using those macros.

Link: https://lkml.kernel.org/r/163163040680.489837.12133032364499833736.stgit@devnote2

Signed-off-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware)

powerpc/kprobes: Fix Oops by passing ppc_inst as a pointer to emulate_step() on ppc32

2021-06-25T04:46:51+00:00

Trying to use a kprobe on ppc32 results in the below splat:
    BUG: Unable to handle kernel data access on read at 0x7c0802a6
    Faulting instruction address: 0xc002e9f0
    Oops: Kernel access of bad area, sig: 11 [#1]
    BE PAGE_SIZE=4K PowerPC 44x Platform
    Modules linked in:
    CPU: 0 PID: 89 Comm: sh Not tainted 5.13.0-rc1-01824-g3a81c0495fdb #7
    NIP:  c002e9f0 LR: c0011858 CTR: 00008a47
    REGS: c292fd50 TRAP: 0300   Not tainted  (5.13.0-rc1-01824-g3a81c0495fdb)
    MSR:  00009000   CR: 24002002  XER: 20000000
    DEAR: 7c0802a6 ESR: 00000000
    
    NIP [c002e9f0] emulate_step+0x28/0x324
    LR [c0011858] optinsn_slot+0x128/0x10000
    Call Trace:
     opt_pre_handler+0x7c/0xb4 (unreliable)
     optinsn_slot+0x128/0x10000
     ret_from_syscall+0x0/0x28

The offending instruction is:
    81 24 00 00     lwz     r9,0(r4)

Here, we are trying to load the second argument to emulate_step():
struct ppc_inst, which is the instruction to be emulated. On ppc64,
structures are passed in registers when passed by value. However, per
the ppc32 ABI, structures are always passed to functions as pointers.
This isn't being adhered to when setting up the call to emulate_step()
in the optprobe trampoline. Fix the same.

Fixes: eacf4c0202654a ("powerpc: Enable OPTPROBES on PPC32")
Cc: stable@vger.kernel.org
Signed-off-by: Naveen N. Rao 
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/5bdc8cbc9a95d0779e27c9ddbf42b40f51f883c0.1624425798.git.christophe.leroy@csgroup.eu

powerpc/64s: avoid reloading (H)SRR registers if they are still valid

2021-06-24T14:06:55+00:00

When an interrupt is taken, the SRR registers are set to return to where
it left off. Unless they are modified in the meantime, or the return
address or MSR are modified, there is no need to reload these registers
when returning from interrupt.

Introduce per-CPU flags that track the validity of SRR and HSRR
registers. These are cleared when returning from interrupt, when
using the registers for something else (e.g., OPAL calls), when
adjusting the return address or MSR of a context, and when context
switching (which changes the return address and MSR).

This improves the performance of interrupt returns.

Signed-off-by: Nicholas Piggin 
[mpe: Fold in fixup patch from Nick]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210617155116.2167984-5-npiggin@gmail.com

powerpc/optprobes: use PPC_RAW_ macros

2021-06-16T14:09:07+00:00

Use PPC_RAW_ macros to simplify the code.

And use PPC_LO/PPC_HI instead of IMM_L/IMM_H which are for
internal use inside ppc-opcode.h

Those macros are self explanatory, comments can go as well.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/5a167b8ba4d33a5c09cd504f0c862e25ffe85459.1621516826.git.christophe.leroy@csgroup.eu