| From 5de0f7eccdd6a2350bc1c2e15c58f4c349b677c9 Mon Sep 17 00:00:00 2001 |
| From: Alex Sverdlin <alexander.sverdlin@nokia.com> |
| Date: Wed, 8 Jan 2020 15:57:47 +0100 |
| Subject: [PATCH] ARM: 8950/1: ftrace/recordmcount: filter relocation types |
| |
| commit 927d780ee371d7e121cea4fc7812f6ef2cea461c upstream. |
| |
| 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. |
| |
| Link: https://lore.kernel.org/lkml/56961010.6000806@pengutronix.de/ |
| Cc: stable@vger.kernel.org |
| Fixes: ed60453fa8f8 ("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> |
| Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c |
| index 8387a9bc064a..9660dc632b54 100644 |
| --- a/scripts/recordmcount.c |
| +++ b/scripts/recordmcount.c |
| @@ -39,6 +39,10 @@ |
| #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 '_') */ |
| @@ -414,6 +418,18 @@ is_mcounted_section_name(char const *const txtname) |
| #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] |
| @@ -515,6 +531,7 @@ 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; |
| break; |
| case EM_AARCH64: |
| reltype = R_AARCH64_ABS64; |
| -- |
| 2.7.4 |
| |
