Re: [PATCH] powerpc: Add ppc_inst_as_u64()
From: Jordan Niethe <hidden>
Date: 2020-05-26 02:41:05
On Mon, May 25, 2020 at 3:49 PM Michael Ellerman [off-list ref] wrote:
The code patching code wants to get the value of a struct ppc_inst as
Might need to change the wording here as it also gets used in arch_prepare_optimized_kprobe()
quoted hunk ↗ jump to hunk
a u64 when the instruction is prefixed, so we can pass the u64 down to __put_user_asm() and write it with a single store. This is a bit awkward because the value differs based on the CPU endianness, so add a helper to do the conversion. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/include/asm/inst.h | 9 +++++++++ arch/powerpc/kernel/optprobes.c | 3 +-- arch/powerpc/lib/code-patching.c | 8 +------- 3 files changed, 11 insertions(+), 9 deletions(-)diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h index d82e0c99cfa1..d61e07fb2937 100644 --- a/arch/powerpc/include/asm/inst.h +++ b/arch/powerpc/include/asm/inst.h@@ -100,6 +100,15 @@ static inline int ppc_inst_len(struct ppc_inst x) return ppc_inst_prefixed(x) ? 8 : 4; } +static inline u64 ppc_inst_as_u64(struct ppc_inst x) +{ +#ifdef CONFIG_CPU_LITTLE_ENDIAN + return (u64)ppc_inst_suffix(x) << 32 | ppc_inst_val(x); +#else + return (u64)ppc_inst_val(x) << 32 | ppc_inst_suffix(x); +#endif +} + int probe_user_read_inst(struct ppc_inst *inst, struct ppc_inst __user *nip);diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c index 3ac105e7faae..69bfe96884e2 100644 --- a/arch/powerpc/kernel/optprobes.c +++ b/arch/powerpc/kernel/optprobes.c@@ -283,8 +283,7 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p) * 3. load instruction to be emulated into relevant register, and */ temp = ppc_inst_read((struct ppc_inst *)p->ainsn.insn); - patch_imm64_load_insns(ppc_inst_val(temp) | ((u64)ppc_inst_suffix(temp) << 32), - 4, buff + TMPL_INSN_IDX); + patch_imm64_load_insns(ppc_inst_as_u64(temp), 4, buff + TMPL_INSN_IDX); /* * 4. branch back from trampolinediff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 64cf621e5b00..5ecf0d635a8d 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c@@ -27,13 +27,7 @@ static int __patch_instruction(struct ppc_inst *exec_addr, struct ppc_inst instr if (!ppc_inst_prefixed(instr)) { __put_user_asm(ppc_inst_val(instr), patch_addr, err, "stw"); } else { -#ifdef CONFIG_CPU_LITTLE_ENDIAN - __put_user_asm((u64)ppc_inst_suffix(instr) << 32 | - ppc_inst_val(instr), patch_addr, err, "std"); -#else - __put_user_asm((u64)ppc_inst_val(instr) << 32 | - ppc_inst_suffix(instr), patch_addr, err, "std"); -#endif + __put_user_asm(ppc_inst_as_u64(instr), patch_addr, err, "std"); } if (err) --2.25.1
I booted a BE and LE kernel - test_prefixed_patching() worked on both. Also on BE and LE kernels I put optprobes on prefixed and non prefixed instructions. The correct value was passed via r4 to emulate_step(). Tested-by: Jordan Niethe <redacted>