linux-dev/arch/powerpc/kernel/optprobes.c, branch linus/master

powerpc/inst: Define ppc_inst_t as u32 on PPC32

2021-12-09T11:41:21Z

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

2021-12-09T11:41:21Z

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

2021-10-01T01:24:06Z

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()

2021-10-01T01:24:05Z

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

2021-06-25T04:46:51Z

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

2021-06-24T14:06:55Z

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

2021-06-16T14:09:07Z

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

powerpc/optprobes: Compact code source a bit.

2021-06-16T14:09:07Z

Now that lines can be up to 100 chars long, minimise the amount of split lines to increase readability. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/8ebbd977ea8cf8d706d82458f2a21acd44562a99.1621516826.git.christophe.leroy@csgroup.eu

powerpc/optprobes: Minimise casts

2021-06-16T14:09:06Z

nip is already an unsigned long, no cast needed. op_callback_addr and emulate_step_addr are kprobe_opcode_t *. There value is obtained with ppc_kallsyms_lookup_name() which returns 'unsigned long', and there values are used create_branch() which expects 'unsigned long'. So change them to 'unsigned long' to avoid casting them back and forth. can_optimize() used p->addr several times as 'unsigned long'. Use a local 'unsigned long' variable and avoid casting multiple times. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/e03192a6d4123242a275e71ce2ba0bb4d90700c1.1621516826.git.christophe.leroy@csgroup.eu

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

2021-06-16T14:09:00Z

'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