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Tue, 13 Feb 2024 04:20:20 +0000 (GMT) Received: from [10.61.2.107] (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id AE07C602C3; Tue, 13 Feb 2024 15:20:17 +1100 (AEDT) Message-ID: Subject: Re: [PATCH] powerpc/ftrace: Ignore ftrace locations in exit text sections From: Benjamin Gray To: Naveen N Rao , linuxppc-dev@lists.ozlabs.org Date: Tue, 13 Feb 2024 15:20:17 +1100 In-Reply-To: <20240209075931.666935-1-naveen@kernel.org> References: <20240209075931.666935-1-naveen@kernel.org> Autocrypt: addr=bgray@linux.ibm.com; prefer-encrypt=mutual; keydata=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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 (3.50.3-1.fc39) MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: qH_JEAsKepCMaPe30ZVP5xJ-llxTklVG X-Proofpoint-ORIG-GUID: qH_JEAsKepCMaPe30ZVP5xJ-llxTklVG X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-02-13_01,2024-02-12_03,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1011 suspectscore=0 bulkscore=0 mlxlogscore=885 malwarescore=0 spamscore=0 adultscore=0 priorityscore=1501 mlxscore=0 phishscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2402130034 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Steven Rostedt Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, 2024-02-09 at 13:29 +0530, Naveen N Rao wrote: > Michael reported that we are seeing ftrace bug on bootup when KASAN > is > enabled, and if we are using -fpatchable-function-entry: >=20 > =C2=A0=C2=A0=C2=A0 ftrace: allocating 47780 entries in 18 pages > =C2=A0=C2=A0=C2=A0 ftrace-powerpc: 0xc0000000020b3d5c: No module provided= for non- > kernel address > =C2=A0=C2=A0=C2=A0 ------------[ ftrace bug ]------------ > =C2=A0=C2=A0=C2=A0 ftrace faulted on modifying > =C2=A0=C2=A0=C2=A0 [] 0xc0000000020b3d5c > =C2=A0=C2=A0=C2=A0 Initializing ftrace call sites > =C2=A0=C2=A0=C2=A0 ftrace record flags: 0 > =C2=A0=C2=A0=C2=A0=C2=A0 (0) > =C2=A0=C2=A0=C2=A0=C2=A0 expected tramp: c00000000008cef4 > =C2=A0=C2=A0=C2=A0 ------------[ cut here ]------------ > =C2=A0=C2=A0=C2=A0 WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2180 > ftrace_bug+0x3c0/0x424 > =C2=A0=C2=A0=C2=A0 Modules linked in: > =C2=A0=C2=A0=C2=A0 CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0-rc3-0012= 0- > g0f71dcfb4aef #860 > =C2=A0=C2=A0=C2=A0 Hardware name: IBM pSeries (emulated by qemu) POWER9 (= raw) > 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries > =C2=A0=C2=A0=C2=A0 NIP:=C2=A0 c0000000003aa81c LR: c0000000003aa818 CTR: = 0000000000000000 > =C2=A0=C2=A0=C2=A0 REGS: c0000000033cfab0 TRAP: 0700=C2=A0=C2=A0 Not tain= ted=C2=A0 (6.5.0-rc3- > 00120-g0f71dcfb4aef) > =C2=A0=C2=A0=C2=A0 MSR:=C2=A0 8000000002021033 =C2= =A0 CR: 28028240=C2=A0 > XER: 00000000 > =C2=A0=C2=A0=C2=A0 CFAR: c0000000002781a8 IRQMASK: 3 > =C2=A0=C2=A0=C2=A0 ... > =C2=A0=C2=A0=C2=A0 NIP [c0000000003aa81c] ftrace_bug+0x3c0/0x424 > =C2=A0=C2=A0=C2=A0 LR [c0000000003aa818] ftrace_bug+0x3bc/0x424 > =C2=A0=C2=A0=C2=A0 Call Trace: > =C2=A0=C2=A0=C2=A0=C2=A0 ftrace_bug+0x3bc/0x424 (unreliable) > =C2=A0=C2=A0=C2=A0=C2=A0 ftrace_process_locs+0x5f4/0x8a0 > =C2=A0=C2=A0=C2=A0=C2=A0 ftrace_init+0xc0/0x1d0 > =C2=A0=C2=A0=C2=A0=C2=A0 start_kernel+0x1d8/0x484 >=20 > With CONFIG_FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY=3Dy and > CONFIG_KASAN=3Dy, compiler emits nops in functions that it generates > for > registering and unregistering global variables (unlike with -pg and > -mprofile-kernel where calls to _mcount() are not generated in those > functions). Those functions then end up in INIT_TEXT and EXIT_TEXT > respectively. We don't expect to see any profiled functions in > EXIT_TEXT, so ftrace_init_nop() assumes that all addresses that > aren't > in the core kernel text belongs to a module. Since these functions do > not match that criteria, we see the above bug. >=20 > Address this by having ftrace ignore all locations in the text exit > sections of vmlinux. >=20 > Fixes: 0f71dcfb4aef ("powerpc/ftrace: Add support for -fpatchable- > function-entry") > Cc: stable@vger.kernel.org > Reported-by: Michael Ellerman > Signed-off-by: Naveen N Rao > --- > =C2=A0arch/powerpc/include/asm/ftrace.h=C2=A0=C2=A0 |=C2=A0 9 +-------- > =C2=A0arch/powerpc/include/asm/sections.h |=C2=A0 1 + > =C2=A0arch/powerpc/kernel/trace/ftrace.c=C2=A0 | 12 ++++++++++++ > =C2=A0arch/powerpc/kernel/vmlinux.lds.S=C2=A0=C2=A0 |=C2=A0 2 ++ > =C2=A04 files changed, 16 insertions(+), 8 deletions(-) >=20 > diff --git a/arch/powerpc/include/asm/ftrace.h > b/arch/powerpc/include/asm/ftrace.h > index 1ebd2ca97f12..d6babd083202 100644 > --- a/arch/powerpc/include/asm/ftrace.h > +++ b/arch/powerpc/include/asm/ftrace.h > @@ -20,14 +20,7 @@ > =C2=A0#ifndef __ASSEMBLY__ > =C2=A0extern void _mcount(void); > =C2=A0 > -static inline unsigned long ftrace_call_adjust(unsigned long addr) > -{ > - if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) > - addr +=3D MCOUNT_INSN_SIZE; > - > - return addr; > -} > - > +unsigned long ftrace_call_adjust(unsigned long addr); > =C2=A0unsigned long prepare_ftrace_return(unsigned long parent, unsigned > long ip, > =C2=A0 =C2=A0=C2=A0=C2=A0 unsigned long sp); > =C2=A0 > diff --git a/arch/powerpc/include/asm/sections.h > b/arch/powerpc/include/asm/sections.h > index ea26665f82cf..d389dcecdb0b 100644 > --- a/arch/powerpc/include/asm/sections.h > +++ b/arch/powerpc/include/asm/sections.h > @@ -14,6 +14,7 @@ typedef struct func_desc func_desc_t; > =C2=A0 > =C2=A0extern char __head_end[]; > =C2=A0extern char __srwx_boundary[]; > +extern char _sexittext[], _eexittext[]; > =C2=A0 > =C2=A0/* Patch sites */ > =C2=A0extern s32 patch__call_flush_branch_caches1; > diff --git a/arch/powerpc/kernel/trace/ftrace.c > b/arch/powerpc/kernel/trace/ftrace.c > index 82010629cf88..b5efd8d7bc01 100644 > --- a/arch/powerpc/kernel/trace/ftrace.c > +++ b/arch/powerpc/kernel/trace/ftrace.c > @@ -27,10 +27,22 @@ > =C2=A0#include > =C2=A0#include > =C2=A0#include > +#include > =C2=A0 > =C2=A0#define NUM_FTRACE_TRAMPS 2 > =C2=A0static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS]; > =C2=A0 > +unsigned long ftrace_call_adjust(unsigned long addr) > +{ > + if (addr >=3D (unsigned long)_sexittext && addr < (unsigned > long)_eexittext) > + return 0; > + > + if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) > + addr +=3D MCOUNT_INSN_SIZE; > + > + return addr; > +} > + > =C2=A0static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, > unsigned long addr, int link) > =C2=A0{ > =C2=A0 ppc_inst_t op; > diff --git a/arch/powerpc/kernel/vmlinux.lds.S > b/arch/powerpc/kernel/vmlinux.lds.S > index 1c5970df3233..9c376ae6857d 100644 > --- a/arch/powerpc/kernel/vmlinux.lds.S > +++ b/arch/powerpc/kernel/vmlinux.lds.S > @@ -281,7 +281,9 @@ SECTIONS > =C2=A0 * to deal with references from __bug_table > =C2=A0 */ > =C2=A0 .exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) { > + _sexittext =3D .; > =C2=A0 EXIT_TEXT > + _eexittext =3D .; > =C2=A0 } > =C2=A0 > =C2=A0 . =3D ALIGN(PAGE_SIZE); >=20 > base-commit: 4ef8376c466ae8b03e632dd8eca1e44315f7dd61 Reviewed-by: Benjamin Gray Fixes what I assume is the same bug I was seeing for a while [ 0.000000][ T0] ftrace-powerpc: 0xc0000000030f4f38: No module provid= ed for non-kernel address [ 0.000000][ T0] ------------[ ftrace bug ]------------ [ 0.000000][ T0] ftrace faulted on modifying=20 [ 0.000000][ T0] [] _sub_D_65535_0+0xc/0x40 [ 0.000000][ T0] Initializing ftrace call sites [ 0.000000][ T0] ftrace record flags: 0 [ 0.000000][ T0] (0) =20 [ 0.000000][ T0] expected tramp: c0000000000a8548 [ 0.000000][ T0] ------------[ cut here ]------------ [ 0.000000][ T0] WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2179= ftrace_bug+0x16c/0x3a0 [ 0.000000][ T0] Modules linked in: [ 0.000000][ T0] CPU: 0 PID: 0 Comm: swapper Not tainted 6.8.0-rc3-02= 361-g892886f9f5b7-dirty #11 [ 0.000000][ T0] Hardware name: IBM pSeries (emulated by qemu) POWER9= (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries [ 0.000000][ T0] NIP: c00000000048a96c LR: c00000000048a968 CTR: 000= 0000000000000 [ 0.000000][ T0] REGS: c000000004fa7ae0 TRAP: 0700 Not tainted (6.= 8.0-rc3-02361-g892886f9f5b7-dirty) [ 0.000000][ T0] MSR: 8000000002021033 CR: = 28028440 XER: 00000000 [ 0.000000][ T0] CFAR: c00000000031db34 IRQMASK: 3=20 [ 0.000000][ T0] GPR00: c00000000048a968 c000000004fa7d80 c0000000026= 45600 0000000000000022=20 [ 0.000000][ T0] GPR04: 0000000000000008 0000000000000001 c0000000003= 26dc4 0000000000000000=20 [ 0.000000][ T0] GPR08: c000000002535600 0000000000000001 c0000000044= 0bee0 0000000048028444=20 [ 0.000000][ T0] GPR12: 0000000000000000 c000000006250000 00000000000= 00000 0000000000000000=20 [ 0.000000][ T0] GPR16: 0000000000000000 0000000000000003 00000000000= 00001 0000000000000000=20 [ 0.000000][ T0] GPR20: c000000004fe8af8 c000000010030428 c0000000045= b90c0 0000000000000000=20 [ 0.000000][ T0] GPR24: 0000000000000000 c000000010030430 c0000000100= 30420 0000000000000000=20 [ 0.000000][ T0] GPR28: c000000001dd9a40 c000000001dd8bc0 c0000000102= a5b00 c0000000102a5b08=20 [ 0.000000][ T0] NIP [c00000000048a96c] ftrace_bug+0x16c/0x3a0 [ 0.000000][ T0] LR [c00000000048a968] ftrace_bug+0x168/0x3a0 [ 0.000000][ T0] Call Trace: [ 0.000000][ T0] [c000000004fa7d80] [c00000000048a968] ftrace_bug+0x1= 68/0x3a0 (unreliable) [ 0.000000][ T0] [c000000004fa7e20] [c00000000048aeec] ftrace_process= _locs+0x34c/0x780 [ 0.000000][ T0] [c000000004fa7ec0] [c0000000030655c0] ftrace_init+0x= c8/0x27c [ 0.000000][ T0] [c000000004fa7f40] [c00000000300d458] start_kernel+0= x1bc/0x528 [ 0.000000][ T0] [c000000004fa7fe0] [c00000000000eaa0] start_here_com= mon+0x1c/0x20 [ 0.000000][ T0] Code: 7fe3fb78 483a31e5 60000000 e93e0008 75290800 4= 0820150 7fc3f378 4bfffc95 7c641b78 387d0f40 4be93189 60000000 <0fe00000> 38= 2100a0 3d22fda6 39000001=20 [ 0.000000][ T0] irq event stamp: 0 [ 0.000000][ T0] hardirqs last enabled at (0): [<0000000000000000>] = 0x0 [ 0.000000][ T0] hardirqs last disabled at (0): [<0000000000000000>] = 0x0 [ 0.000000][ T0] softirqs last enabled at (0): [<0000000000000000>] = 0x0 [ 0.000000][ T0] softirqs last disabled at (0): [<0000000000000000>] = 0x0 [ 0.000000][ T0] ---[ end trace 0000000000000000 ]---