From: Guo Ren guoren@linux.alibaba.com
commit 5ad84adf5456313e285734102367c861c436c5ed upstream.
Just like arm64, we can't trace the function in the patch_text path.
Here is the bug log:
[ 45.234334] Unable to handle kernel paging request at virtual address ffffffd38ae80900 [ 45.242313] Oops [#1] [ 45.244600] Modules linked in: [ 45.247678] CPU: 0 PID: 11 Comm: migration/0 Not tainted 5.9.0-00025-g9b7db83-dirty #215 [ 45.255797] epc: ffffffe00021689a ra : ffffffe00021718e sp : ffffffe01afabb58 [ 45.262955] gp : ffffffe00136afa0 tp : ffffffe01af94d00 t0 : 0000000000000002 [ 45.270200] t1 : 0000000000000000 t2 : 0000000000000001 s0 : ffffffe01afabc08 [ 45.277443] s1 : ffffffe0013718a8 a0 : 0000000000000000 a1 : ffffffe01afabba8 [ 45.284686] a2 : 0000000000000000 a3 : 0000000000000000 a4 : c4c16ad38ae80900 [ 45.291929] a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000052464e43 [ 45.299173] s2 : 0000000000000001 s3 : ffffffe000206a60 s4 : ffffffe000206a60 [ 45.306415] s5 : 00000000000009ec s6 : ffffffe0013718a8 s7 : c4c16ad38ae80900 [ 45.313658] s8 : 0000000000000004 s9 : 0000000000000001 s10: 0000000000000001 [ 45.320902] s11: 0000000000000003 t3 : 0000000000000001 t4 : ffffffffd192fe79 [ 45.328144] t5 : ffffffffb8f80000 t6 : 0000000000040000 [ 45.333472] status: 0000000200000100 badaddr: ffffffd38ae80900 cause: 000000000000000f [ 45.341514] ---[ end trace d95102172248fdcf ]--- [ 45.346176] note: migration/0[11] exited with preempt_count 1
(gdb) x /2i $pc => 0xffffffe00021689a <__do_proc_dointvec+196>: sd zero,0(s7) 0xffffffe00021689e <__do_proc_dointvec+200>: li s11,0
(gdb) bt 0 __do_proc_dointvec (tbl_data=0x0, table=0xffffffe01afabba8, write=0, buffer=0x0, lenp=0x7bf897061f9a0800, ppos=0x4, conv=0x0, data=0x52464e43) at kernel/sysctl.c:581 1 0xffffffe00021718e in do_proc_dointvec (data=<optimized out>, conv=<optimized out>, ppos=<optimized out>, lenp=<optimized out>, buffer=<optimized out>, write=<optimized out>, table=<optimized out>) at kernel/sysctl.c:964 2 proc_dointvec_minmax (ppos=<optimized out>, lenp=<optimized out>, buffer=<optimized out>, write=<optimized out>, table=<optimized out>) at kernel/sysctl.c:964 3 proc_do_static_key (table=<optimized out>, write=1, buffer=0x0, lenp=0x0, ppos=0x7bf897061f9a0800) at kernel/sysctl.c:1643 4 0xffffffe000206792 in ftrace_make_call (rec=<optimized out>, addr=<optimized out>) at arch/riscv/kernel/ftrace.c:109 5 0xffffffe0002c9c04 in __ftrace_replace_code (rec=0xffffffe01ae40c30, enable=3) at kernel/trace/ftrace.c:2503 6 0xffffffe0002ca0b2 in ftrace_replace_code (mod_flags=<optimized out>) at kernel/trace/ftrace.c:2530 7 0xffffffe0002ca26a in ftrace_modify_all_code (command=5) at kernel/trace/ftrace.c:2677 8 0xffffffe0002ca30e in __ftrace_modify_code (data=<optimized out>) at kernel/trace/ftrace.c:2703 9 0xffffffe0002c13b0 in multi_cpu_stop (data=0x0) at kernel/stop_machine.c:224 10 0xffffffe0002c0fde in cpu_stopper_thread (cpu=<optimized out>) at kernel/stop_machine.c:491 11 0xffffffe0002343de in smpboot_thread_fn (data=0x0) at kernel/smpboot.c:165 12 0xffffffe00022f8b4 in kthread (_create=0xffffffe01af0c040) at kernel/kthread.c:292 13 0xffffffe000201fac in handle_exception () at arch/riscv/kernel/entry.S:236
0xffffffe00020678a <+114>: auipc ra,0xffffe 0xffffffe00020678e <+118>: jalr -118(ra) # 0xffffffe000204714 <patch_text_nosync> 0xffffffe000206792 <+122>: snez a0,a0
(gdb) disassemble patch_text_nosync Dump of assembler code for function patch_text_nosync: 0xffffffe000204714 <+0>: addi sp,sp,-32 0xffffffe000204716 <+2>: sd s0,16(sp) 0xffffffe000204718 <+4>: sd ra,24(sp) 0xffffffe00020471a <+6>: addi s0,sp,32 0xffffffe00020471c <+8>: auipc ra,0x0 0xffffffe000204720 <+12>: jalr -384(ra) # 0xffffffe00020459c <patch_insn_write> 0xffffffe000204724 <+16>: beqz a0,0xffffffe00020472e <patch_text_nosync+26> 0xffffffe000204726 <+18>: ld ra,24(sp) 0xffffffe000204728 <+20>: ld s0,16(sp) 0xffffffe00020472a <+22>: addi sp,sp,32 0xffffffe00020472c <+24>: ret 0xffffffe00020472e <+26>: sd a0,-24(s0) 0xffffffe000204732 <+30>: auipc ra,0x4 0xffffffe000204736 <+34>: jalr -1464(ra) # 0xffffffe00020817a <flush_icache_all> 0xffffffe00020473a <+38>: ld a0,-24(s0) 0xffffffe00020473e <+42>: ld ra,24(sp) 0xffffffe000204740 <+44>: ld s0,16(sp) 0xffffffe000204742 <+46>: addi sp,sp,32 0xffffffe000204744 <+48>: ret
(gdb) disassemble flush_icache_all-4 Dump of assembler code for function flush_icache_all: 0xffffffe00020817a <+0>: addi sp,sp,-8 0xffffffe00020817c <+2>: sd ra,0(sp) 0xffffffe00020817e <+4>: auipc ra,0xfffff 0xffffffe000208182 <+8>: jalr -1822(ra) # 0xffffffe000206a60 <ftrace_caller> 0xffffffe000208186 <+12>: ld ra,0(sp) 0xffffffe000208188 <+14>: addi sp,sp,8 0xffffffe00020818a <+0>: addi sp,sp,-16 0xffffffe00020818c <+2>: sd s0,0(sp) 0xffffffe00020818e <+4>: sd ra,8(sp) 0xffffffe000208190 <+6>: addi s0,sp,16 0xffffffe000208192 <+8>: li a0,0 0xffffffe000208194 <+10>: auipc ra,0xfffff 0xffffffe000208198 <+14>: jalr -410(ra) # 0xffffffe000206ffa <sbi_remote_fence_i> 0xffffffe00020819c <+18>: ld s0,0(sp) 0xffffffe00020819e <+20>: ld ra,8(sp) 0xffffffe0002081a0 <+22>: addi sp,sp,16 0xffffffe0002081a2 <+24>: ret
(gdb) frame 5 (rec=0xffffffe01ae40c30, enable=3) at kernel/trace/ftrace.c:2503 2503 return ftrace_make_call(rec, ftrace_addr); (gdb) p /x rec->ip $2 = 0xffffffe00020817a -> flush_icache_all !
When we modified flush_icache_all's patchable-entry with ftrace_caller: - Insert ftrace_caller at flush_icache_all prologue. - Call flush_icache_all to sync I/Dcache, but flush_icache_all is just we modified by half.
Link: https://lore.kernel.org/linux-riscv/CAJF2gTT=oDWesWe0JVWvTpGi60-gpbNhYLdFWN_... Signed-off-by: Guo Ren guoren@linux.alibaba.com Reviewed-by: Atish Patra atish.patra@wdc.com Signed-off-by: Palmer Dabbelt palmerdabbelt@google.com Signed-off-by: Dimitri John Ledkov dimitri.ledkov@canonical.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/riscv/kernel/Makefile | 1 + arch/riscv/mm/Makefile | 1 + 2 files changed, 2 insertions(+)
--- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -6,6 +6,7 @@ ifdef CONFIG_FTRACE CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE) CFLAGS_REMOVE_patch.o = $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_sbi.o = $(CC_FLAGS_FTRACE) endif
extra-y += head.o --- a/arch/riscv/mm/Makefile +++ b/arch/riscv/mm/Makefile @@ -3,6 +3,7 @@ CFLAGS_init.o := -mcmodel=medany ifdef CONFIG_FTRACE CFLAGS_REMOVE_init.o = $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_cacheflush.o = $(CC_FLAGS_FTRACE) endif
KCOV_INSTRUMENT_init.o := n