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Rao" , Mark Rutland , Daniel Borkmann , Masahiro Yamada , Nicholas Piggin , Alexei Starovoitov , Steven Rostedt , Masami Hiramatsu , Andrii Nakryiko , Christophe Leroy , Vishal Chourasia , Mahesh J Salgaonkar Subject: [PATCH v6 14/17] powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPS Date: Fri, 18 Oct 2024 23:06:29 +0530 Message-ID: <20241018173632.277333-15-hbathini@linux.ibm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241018173632.277333-1-hbathini@linux.ibm.com> References: <20241018173632.277333-1-hbathini@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 8PsWW1uuVYjNgKAh16cJMLi_NYoM670d X-Proofpoint-ORIG-GUID: _vyDM6ZQAjg0I4oByXi4m-BgMfNtt8Dy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1051,Hydra:6.0.680,FMLib:17.12.62.30 definitions=2024-10-15_01,2024-10-11_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 mlxscore=0 spamscore=0 priorityscore=1501 phishscore=0 clxscore=1015 mlxlogscore=651 impostorscore=0 bulkscore=0 malwarescore=0 lowpriorityscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2410180111 Content-Type: text/plain; charset="utf-8" From: Naveen N Rao Implement support for DYNAMIC_FTRACE_WITH_CALL_OPS similar to the arm64 implementation. This works by patching-in a pointer to an associated ftrace_ops structure before each traceable function. If multiple ftrace_ops are associated with a call site, then a special ftrace_list_ops is used to enable iterating over all the registered ftrace_ops. If no ftrace_ops are associated with a call site, then a special ftrace_nop_ops structure is used to render the ftrace call as a no-op. ftrace trampoline can then read the associated ftrace_ops for a call site by loading from an offset from the LR, and branch directly to the associated function. The primary advantage with this approach is that we don't have to iterate over all the registered ftrace_ops for call sites that have a single ftrace_ops registered. This is the equivalent of implementing support for dynamic ftrace trampolines, which set up a special ftrace trampoline for each registered ftrace_ops and have individual call sites branch into those directly. A secondary advantage is that this gives us a way to add support for direct ftrace callers without having to resort to using stubs. The address of the direct call trampoline can be loaded from the ftrace_ops structure. To support this, we reserve a nop before each function on 32-bit powerpc. For 64-bit powerpc, two nops are reserved before each out-of-line stub. During ftrace activation, we update this location with the associated ftrace_ops pointer. Then, on ftrace entry, we load from this location and call into ftrace_ops->func(). For 64-bit powerpc, we ensure that the out-of-line stub area is doubleword aligned so that ftrace_ops address can be updated atomically. Signed-off-by: Naveen N Rao --- arch/powerpc/Kconfig | 1 + arch/powerpc/Makefile | 4 ++ arch/powerpc/include/asm/ftrace.h | 5 +- arch/powerpc/kernel/asm-offsets.c | 4 ++ arch/powerpc/kernel/trace/ftrace.c | 59 +++++++++++++++++++++- arch/powerpc/kernel/trace/ftrace_entry.S | 36 ++++++++++--- arch/powerpc/tools/ftrace-gen-ool-stubs.sh | 5 +- 7 files changed, 102 insertions(+), 12 deletions(-) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 2e347f682c15..5c5db85c2097 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -234,6 +234,7 @@ config PPC select HAVE_DEBUG_STACKOVERFLOW select HAVE_DYNAMIC_FTRACE select HAVE_DYNAMIC_FTRACE_WITH_ARGS if ARCH_USING_PATCHABLE_FUNCTION_ENT= RY || MPROFILE_KERNEL || PPC32 + select HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS if PPC_FTRACE_OUT_OF_LINE || (PP= C32 && ARCH_USING_PATCHABLE_FUNCTION_ENTRY) select HAVE_DYNAMIC_FTRACE_WITH_REGS if ARCH_USING_PATCHABLE_FUNCTION_ENT= RY || MPROFILE_KERNEL || PPC32 select HAVE_EBPF_JIT select HAVE_EFFICIENT_UNALIGNED_ACCESS diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index c973e6cd1ae8..7dede0ec0163 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -158,8 +158,12 @@ KBUILD_CPPFLAGS +=3D -DCC_USING_PATCHABLE_FUNCTION_ENT= RY ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE CC_FLAGS_FTRACE :=3D -fpatchable-function-entry=3D1 else +ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS # PPC32 only +CC_FLAGS_FTRACE :=3D -fpatchable-function-entry=3D3,1 +else CC_FLAGS_FTRACE :=3D -fpatchable-function-entry=3D2 endif +endif else CC_FLAGS_FTRACE :=3D -pg ifdef CONFIG_MPROFILE_KERNEL diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/f= trace.h index 28f3590ca780..1ad1328cf4e3 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -136,8 +136,11 @@ static inline u8 this_cpu_get_ftrace_enabled(void) { r= eturn 1; } extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[]; #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE struct ftrace_ool_stub { +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS + struct ftrace_ops *ftrace_op; +#endif u32 insn[4]; -}; +} __aligned(sizeof(unsigned long)); extern struct ftrace_ool_stub ftrace_ool_stub_text_end[], ftrace_ool_stub_= text[], ftrace_ool_stub_inittext[]; extern unsigned int ftrace_ool_stub_text_end_count, ftrace_ool_stub_text_c= ount, diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-of= fsets.c index 9f27ea489cd4..557abe800470 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -680,5 +680,9 @@ int main(void) DEFINE(FTRACE_OOL_STUB_SIZE, sizeof(struct ftrace_ool_stub)); #endif =20 +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS + OFFSET(FTRACE_OPS_FUNC, ftrace_ops, func); +#endif + return 0; } diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace= /ftrace.c index bee2c54a8c04..9090d1a21600 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -38,8 +38,11 @@ unsigned long ftrace_call_adjust(unsigned long addr) return 0; =20 if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY) && - !IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) + !IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) { addr +=3D MCOUNT_INSN_SIZE; + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS)) + addr +=3D MCOUNT_INSN_SIZE; + } =20 return addr; } @@ -264,6 +267,46 @@ static int ftrace_init_ool_stub(struct module *mod, st= ruct dyn_ftrace *rec) #endif } =20 +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS +static const struct ftrace_ops *powerpc_rec_get_ops(struct dyn_ftrace *rec) +{ + const struct ftrace_ops *ops =3D NULL; + + if (rec->flags & FTRACE_FL_CALL_OPS_EN) { + ops =3D ftrace_find_unique_ops(rec); + WARN_ON_ONCE(!ops); + } + + if (!ops) + ops =3D &ftrace_list_ops; + + return ops; +} + +static int ftrace_rec_set_ops(struct dyn_ftrace *rec, const struct ftrace_= ops *ops) +{ + if (IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) + return patch_ulong((void *)(ftrace_get_ool_stub(rec) - sizeof(unsigned l= ong)), + (unsigned long)ops); + else + return patch_ulong((void *)(rec->ip - MCOUNT_INSN_SIZE - sizeof(unsigned= long)), + (unsigned long)ops); +} + +static int ftrace_rec_set_nop_ops(struct dyn_ftrace *rec) +{ + return ftrace_rec_set_ops(rec, &ftrace_nop_ops); +} + +static int ftrace_rec_update_ops(struct dyn_ftrace *rec) +{ + return ftrace_rec_set_ops(rec, powerpc_rec_get_ops(rec)); +} +#else +static int ftrace_rec_set_nop_ops(struct dyn_ftrace *rec) { return 0; } +static int ftrace_rec_update_ops(struct dyn_ftrace *rec) { return 0; } +#endif + #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, uns= igned long addr) { @@ -294,6 +337,10 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned = long addr) if (!ret) ret =3D ftrace_modify_code(ip, old, new); =20 + ret =3D ftrace_rec_update_ops(rec); + if (ret) + return ret; + if (!ret && IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE)) ret =3D ftrace_modify_code(rec->ip, ppc_inst(PPC_RAW_NOP()), ppc_inst(PPC_RAW_BRANCH((long)ftrace_get_ool_stub(rec) - (long)rec->ip= ))); @@ -345,16 +392,19 @@ void ftrace_replace_code(int enable) case FTRACE_UPDATE_MODIFY_CALL: ret =3D ftrace_get_call_inst(rec, new_addr, &new_call_inst); ret |=3D ftrace_get_call_inst(rec, addr, &call_inst); + ret |=3D ftrace_rec_update_ops(rec); old =3D call_inst; new =3D new_call_inst; break; case FTRACE_UPDATE_MAKE_NOP: ret =3D ftrace_get_call_inst(rec, addr, &call_inst); + ret |=3D ftrace_rec_set_nop_ops(rec); old =3D call_inst; new =3D nop_inst; break; case FTRACE_UPDATE_MAKE_CALL: ret =3D ftrace_get_call_inst(rec, new_addr, &call_inst); + ret |=3D ftrace_rec_update_ops(rec); old =3D nop_inst; new =3D call_inst; break; @@ -470,6 +520,13 @@ int ftrace_update_ftrace_func(ftrace_func_t func) ppc_inst_t old, new; int ret; =20 + /* + * When using CALL_OPS, the function to call is associated with the + * call site, and we don't have a global function pointer to update. + */ + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS)) + return 0; + old =3D ppc_inst_read((u32 *)&ftrace_call); new =3D ftrace_create_branch_inst(ip, ppc_function_entry(func), 1); ret =3D ftrace_modify_code(ip, old, new); diff --git a/arch/powerpc/kernel/trace/ftrace_entry.S b/arch/powerpc/kernel= /trace/ftrace_entry.S index a6bf7f841040..ff376c990308 100644 --- a/arch/powerpc/kernel/trace/ftrace_entry.S +++ b/arch/powerpc/kernel/trace/ftrace_entry.S @@ -85,11 +85,21 @@ /* Save callee's TOC in the ABI compliant location */ std r2, STK_GOT(r1) LOAD_PACA_TOC() /* get kernel TOC in r2 */ +#endif + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS + /* r7 points to the instruction following the call to ftrace */ + PPC_LL r5, -(MCOUNT_INSN_SIZE*2 + SZL)(r7) + PPC_LL r12, FTRACE_OPS_FUNC(r5) + mtctr r12 +#else /* !CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS */ +#ifdef CONFIG_PPC64 LOAD_REG_ADDR(r3, function_trace_op) ld r5,0(r3) #else lis r3,function_trace_op@ha lwz r5,function_trace_op@l(r3) +#endif #endif =20 /* Save special regs */ @@ -205,20 +215,30 @@ #endif .endm =20 -_GLOBAL(ftrace_regs_caller) - ftrace_regs_entry 1 - /* ftrace_call(r3, r4, r5, r6) */ +.macro ftrace_regs_func allregs +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS + bctrl +#else + .if \allregs =3D=3D 1 .globl ftrace_regs_call ftrace_regs_call: + .else +.globl ftrace_call +ftrace_call: + .endif + /* ftrace_call(r3, r4, r5, r6) */ bl ftrace_stub +#endif +.endm + +_GLOBAL(ftrace_regs_caller) + ftrace_regs_entry 1 + ftrace_regs_func 1 ftrace_regs_exit 1 =20 _GLOBAL(ftrace_caller) ftrace_regs_entry 0 - /* ftrace_call(r3, r4, r5, r6) */ -.globl ftrace_call -ftrace_call: - bl ftrace_stub + ftrace_regs_func 0 ftrace_regs_exit 0 =20 _GLOBAL(ftrace_stub) @@ -377,7 +397,7 @@ _GLOBAL(return_to_handler) #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE SYM_DATA(ftrace_ool_stub_text_count, .long CONFIG_PPC_FTRACE_OUT_OF_LINE_N= UM_RESERVE) =20 -SYM_CODE_START(ftrace_ool_stub_text) +SYM_START(ftrace_ool_stub_text, SYM_L_GLOBAL, .balign SZL) .space CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE * FTRACE_OOL_STUB_SIZE SYM_CODE_END(ftrace_ool_stub_text) #endif diff --git a/arch/powerpc/tools/ftrace-gen-ool-stubs.sh b/arch/powerpc/tool= s/ftrace-gen-ool-stubs.sh index 3ea0f23f2501..76df5a3e8cf7 100755 --- a/arch/powerpc/tools/ftrace-gen-ool-stubs.sh +++ b/arch/powerpc/tools/ftrace-gen-ool-stubs.sh @@ -28,12 +28,13 @@ fi =20 cat > "$arch_vmlinux_S" < +#include #include =20 .pushsection .tramp.ftrace.text,"aw" SYM_DATA(ftrace_ool_stub_text_end_count, .long $num_ool_stubs_text_end) =20 -SYM_CODE_START(ftrace_ool_stub_text_end) +SYM_START(ftrace_ool_stub_text_end, SYM_L_GLOBAL, .balign SZL) .space $num_ool_stubs_text_end * FTRACE_OOL_STUB_SIZE SYM_CODE_END(ftrace_ool_stub_text_end) .popsection @@ -41,7 +42,7 @@ SYM_CODE_END(ftrace_ool_stub_text_end) .pushsection .tramp.ftrace.init,"aw" SYM_DATA(ftrace_ool_stub_inittext_count, .long $num_ool_stubs_inittext) =20 -SYM_CODE_START(ftrace_ool_stub_inittext) +SYM_START(ftrace_ool_stub_inittext, SYM_L_GLOBAL, .balign SZL) .space $num_ool_stubs_inittext * FTRACE_OOL_STUB_SIZE SYM_CODE_END(ftrace_ool_stub_inittext) .popsection --=20 2.47.0