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received-spf: None (protection.outlook.com: nokia.com does not designate permitted sender hosts) x-microsoft-antispam-message-info: C99ILHFKm24T/BmyfcQMy0x0WA75Elc9cJeWY3lFVT7vOyE66Tmm2F3K+TBu1dCgaVD9qUUAT5glYuDKJxtW24tictC9gRjZguWQnd72SwzDiFRkQ6HGtXGMonI/9C3y7qYFCeHge9t34NKbKslALRYVmjdM+N22BfO3iUcP+s+oX0n2xJYPQS6asFdXt7qcwndsljgqcqWcumj9MhdV3WpcYUdaSk9Kxb+yQxEw7PZomxOUe1HgltGzZENujwjp6idf7PMDsQkx6TYJluJ7aUzyzCnBk4IVzqGjnraYsldFnzU5hj/8P036VnO0Qoq+SEi3dHZ5uKJjADHA48nklKC3DNMntuXiDy0YjU1nlSQ= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nokia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 442aff19-02c6-4ccf-c231-08d6590487f4 X-MS-Exchange-CrossTenant-originalarrivaltime: 03 Dec 2018 09:48:52.8460 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 5d471751-9675-428d-917b-70f44f9630b0 X-MS-Exchange-Transport-CrossTenantHeadersStamped: HE1PR0701MB2890 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Scenario 1, ARMv7: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D If code in arch/arm/kernel/ftrace.c would operate on mcount() pointer the following may be generated: 00000230 : 230: b5f8 push {r3, r4, r5, r6, r7, lr} 232: b500 push {lr} 234: f7ff fffe bl 0 <__gnu_mcount_nc> 234: R_ARM_THM_CALL __gnu_mcount_nc 238: f240 0600 movw r6, #0 238: R_ARM_THM_MOVW_ABS_NC __gnu_mcount_nc 23c: f8d0 1180 ldr.w r1, [r0, #384] ; 0x180 FTRACE currently is not able to deal with it: WARNING: CPU: 0 PID: 0 at .../kernel/trace/ftrace.c:1979 ftrace_bug+0x1ad/0= x230() ... CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.116-... #1 ... [] (unwind_backtrace) from [] (show_stack+0x11/0x14) [] (show_stack) from [] (dump_stack+0x81/0xa8) [] (dump_stack) from [] (warn_slowpath_common+0x69/0x90= ) [] (warn_slowpath_common) from [] (warn_slowpath_null+0= x17/0x1c) [] (warn_slowpath_null) from [] (ftrace_bug+0x1ad/0x230= ) [] (ftrace_bug) from [] (ftrace_process_locs+0x27d/0x44= 4) [] (ftrace_process_locs) from [] (ftrace_init+0x91/0xe8= ) [] (ftrace_init) from [] (start_kernel+0x34b/0x358) [] (start_kernel) from [<00308095>] (0x308095) ---[ end trace cb88537fdc8fa200 ]--- ftrace failed to modify [] prealloc_fixed_plts+0x8/0x60 actual: 44:f2:e1:36 ftrace record flags: 0 (0) expected tramp: c03143e9 Scenario 2, ARMv4T: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D ftrace: allocating 14435 entries in 43 pages ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2029 ftrace_bug+0x204/0x310 CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.5 #1 Hardware name: Cirrus Logic EDB9302 Evaluation Board [] (unwind_backtrace) from [] (show_stack+0x20/0x2c) [] (show_stack) from [] (dump_stack+0x20/0x30) [] (dump_stack) from [] (__warn+0xdc/0x104) [] (__warn) from [] (warn_slowpath_null+0x4c/0x5c) [] (warn_slowpath_null) from [] (ftrace_bug+0x204/0x310= ) [] (ftrace_bug) from [] (ftrace_init+0x3b4/0x4d4) [] (ftrace_init) from [] (start_kernel+0x20c/0x410) [] (start_kernel) from [<00000000>] ( (null)) ---[ end trace 0506a2f5dae6b341 ]--- ftrace failed to modify [] perf_trace_sys_exit+0x5c/0xe8 actual: 1e:ff:2f:e1 Initializing ftrace call sites ftrace record flags: 0 (0) expected tramp: c000fb24 The analysis for this problem has been already performed previously, refer to the link below. Fix the above problems by allowing only selected reloc types in __mcount_loc. The list itself comes from the legacy recordmcount.pl script. Cc: stable@vger.kernel.org Link: https://lore.kernel.org/lkml/56961010.6000806@pengutronix.de/ Fixes: ed60453fa8 ("ARM: 6511/1: ftrace: add ARM support for C version of r= ecordmcount") Signed-off-by: Alexander Sverdlin --- scripts/recordmcount.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c index 895c40e8679f..3b0dcf38fd8b 100644 --- a/scripts/recordmcount.c +++ b/scripts/recordmcount.c @@ -39,6 +39,10 @@ #define R_AARCH64_ABS64 257 #endif =20 +#define R_ARM_PC24 1 +#define R_ARM_THM_CALL 10 +#define R_ARM_CALL 28 + static int fd_map; /* File descriptor for file being modified. */ static int mmap_failed; /* Boolean flag. */ static char gpfx; /* prefix for global symbol name (sometimes '_') */ @@ -414,6 +418,18 @@ is_mcounted_section_name(char const *const txtname) #define RECORD_MCOUNT_64 #include "recordmcount.h" =20 +static int arm_is_fake_mcount(Elf32_Rel const *rp) +{ + switch (ELF32_R_TYPE(w(rp->r_info))) { + case R_ARM_THM_CALL: + case R_ARM_CALL: + case R_ARM_PC24: + return 0; + } + + return 1; +} + /* 64-bit EM_MIPS has weird ELF64_Rela.r_info. * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-= 001.pdf * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.4= 0] @@ -515,6 +531,7 @@ do_file(char const *const fname) altmcount =3D "__gnu_mcount_nc"; make_nop =3D make_nop_arm; rel_type_nop =3D R_ARM_NONE; + is_fake_mcount32 =3D arm_is_fake_mcount; break; case EM_AARCH64: reltype =3D R_AARCH64_ABS64; --=20 2.19.2