| Message ID | 20191106154209.118919-1-alexander.sverdlin@nokia.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 927d780ee371d7e121cea4fc7812f6ef2cea461c |
| Headers | show |
| Series | [v2] ARM: ftrace/recordmcount: filter relocation types | expand |
On Wed, 6 Nov 2019 15:42:24 +0000 "Sverdlin, Alexander (Nokia - DE/Ulm)" <alexander.sverdlin@nokia.com> wrote: > From: Alexander Sverdlin <alexander.sverdlin@nokia.com> > > Scenario 1, ARMv7 > ================= > > If code in arch/arm/kernel/ftrace.c would operate on mcount() pointer > the following may be generated: > > 00000230 <prealloc_fixed_plts>: > 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/0x230() > ... > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.116-... #1 > ... > [<c0314e3d>] (unwind_backtrace) from [<c03115e9>] (show_stack+0x11/0x14) > [<c03115e9>] (show_stack) from [<c051a7f1>] (dump_stack+0x81/0xa8) > [<c051a7f1>] (dump_stack) from [<c0321c5d>] (warn_slowpath_common+0x69/0x90) > [<c0321c5d>] (warn_slowpath_common) from [<c0321cf3>] (warn_slowpath_null+0x17/0x1c) > [<c0321cf3>] (warn_slowpath_null) from [<c038ee9d>] (ftrace_bug+0x1ad/0x230) > [<c038ee9d>] (ftrace_bug) from [<c038f1f9>] (ftrace_process_locs+0x27d/0x444) > [<c038f1f9>] (ftrace_process_locs) from [<c08915bd>] (ftrace_init+0x91/0xe8) > [<c08915bd>] (ftrace_init) from [<c0885a67>] (start_kernel+0x34b/0x358) > [<c0885a67>] (start_kernel) from [<00308095>] (0x308095) > ---[ end trace cb88537fdc8fa200 ]--- > ftrace failed to modify [<c031266c>] prealloc_fixed_plts+0x8/0x60 > actual: 44:f2:e1:36 > ftrace record flags: 0 > (0) expected tramp: c03143e9 > > Scenario 2, ARMv4T > ================== > > 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 > [<c0010a24>] (unwind_backtrace) from [<c000ecb0>] (show_stack+0x20/0x2c) > [<c000ecb0>] (show_stack) from [<c03c72e8>] (dump_stack+0x20/0x30) > [<c03c72e8>] (dump_stack) from [<c0021c18>] (__warn+0xdc/0x104) > [<c0021c18>] (__warn) from [<c0021d7c>] (warn_slowpath_null+0x4c/0x5c) > [<c0021d7c>] (warn_slowpath_null) from [<c0095360>] (ftrace_bug+0x204/0x310) > [<c0095360>] (ftrace_bug) from [<c04dabac>] (ftrace_init+0x3b4/0x4d4) > [<c04dabac>] (ftrace_init) from [<c04cef4c>] (start_kernel+0x20c/0x410) > [<c04cef4c>] (start_kernel) from [<00000000>] ( (null)) > ---[ end trace 0506a2f5dae6b341 ]--- > ftrace failed to modify > [<c000c350>] 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 recordmcount") > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Feel free to take this in whatever tree you want. -- Steve > > --- > Changelog: > v2: Rebased > > scripts/recordmcount.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c > index 612268e..6872d26 100644 > --- a/scripts/recordmcount.c > +++ b/scripts/recordmcount.c > @@ -38,6 +38,10 @@ > #define R_AARCH64_ABS64 257 > #endif > > +#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 '_') */ > @@ -418,6 +422,18 @@ static char const *already_has_rel_mcount = "success"; /* our work here is done! > #define RECORD_MCOUNT_64 > #include "recordmcount.h" > > +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.40] > @@ -523,6 +539,7 @@ static int do_file(char const *const fname) > altmcount = "__gnu_mcount_nc"; > make_nop = make_nop_arm; > rel_type_nop = R_ARM_NONE; > + is_fake_mcount32 = arm_is_fake_mcount; > gpfx = 0; > break; > case EM_AARCH64:
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c index 612268e..6872d26 100644 --- a/scripts/recordmcount.c +++ b/scripts/recordmcount.c @@ -38,6 +38,10 @@ #define R_AARCH64_ABS64 257 #endif +#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 '_') */ @@ -418,6 +422,18 @@ static char const *already_has_rel_mcount = "success"; /* our work here is done! #define RECORD_MCOUNT_64 #include "recordmcount.h" +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.40] @@ -523,6 +539,7 @@ static int do_file(char const *const fname) altmcount = "__gnu_mcount_nc"; make_nop = make_nop_arm; rel_type_nop = R_ARM_NONE; + is_fake_mcount32 = arm_is_fake_mcount; gpfx = 0; break; case EM_AARCH64: