| Message ID | 20201127084502.2133722-1-chenhuang5@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | riscv/stacktrace: fix stackframe without ra on the top | expand |
On 2020/11/27 16:45, Chen Huang wrote: > When a function doesn't have a callee, then it will not push ra > into the stack, such as lkdtm_BUG() function: > > addi sp,sp,-16 > sd s0,8(sp) > addi s0,sp,16 > ebreak > > Then we use pt_regs as a parameter to walk_stackframe(), for the > struct stackframe use {fp,ra} to get information from stack, it > will get the wrong value. And the call trace will be: > > [<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8 > ---[ end trace 18da3fbdf08e25d5 ]--- > > It should be that: > [<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8 > [<ffffffe0008b24a4>] lkdtm_do_action+0x14/0x1c > [<ffffffe00066c372>] direct_entry+0xc0/0x10a > [<ffffffe000439f86>] full_proxy_write+0x42/0x6a > [<ffffffe000309626>] vfs_write+0x7e/0x214 > [<ffffffe00030992a>] ksys_write+0x98/0xc0 > [<ffffffe000309960>] sys_write+0xe/0x16 > [<ffffffe0002014bc>] ret_from_syscall+0x0/0x2 > ---[ end trace 61917f3d9a9fadcd ]--- > > Signed-off-by: Chen Huang <chenhuang5@huawei.com> > --- > arch/riscv/kernel/stacktrace.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c > index 595342910c3f..d1d4c18335c4 100644 > --- a/arch/riscv/kernel/stacktrace.c > +++ b/arch/riscv/kernel/stacktrace.c > @@ -57,7 +57,14 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, > /* Unwind stack frame */ > frame = (struct stackframe *)fp - 1; > sp = fp; > - fp = frame->fp; > + if (regs && (frame->fp & 0x7) && (pc == regs->epc)) { > + fp = frame->ra; > + pc = regs->ra; > + continue; > + } else { > + fp = frame->fp; > + } > + > pc = ftrace_graph_ret_addr(current, NULL, frame->ra, > (unsigned long *)(fp - 8)); Better to move above code into else branch > }
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c index 595342910c3f..d1d4c18335c4 100644 --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -57,7 +57,14 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, /* Unwind stack frame */ frame = (struct stackframe *)fp - 1; sp = fp; - fp = frame->fp; + if (regs && (frame->fp & 0x7) && (pc == regs->epc)) { + fp = frame->ra; + pc = regs->ra; + continue; + } else { + fp = frame->fp; + } + pc = ftrace_graph_ret_addr(current, NULL, frame->ra, (unsigned long *)(fp - 8)); }
When a function doesn't have a callee, then it will not push ra into the stack, such as lkdtm_BUG() function: addi sp,sp,-16 sd s0,8(sp) addi s0,sp,16 ebreak Then we use pt_regs as a parameter to walk_stackframe(), for the struct stackframe use {fp,ra} to get information from stack, it will get the wrong value. And the call trace will be: [<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8 ---[ end trace 18da3fbdf08e25d5 ]--- It should be that: [<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8 [<ffffffe0008b24a4>] lkdtm_do_action+0x14/0x1c [<ffffffe00066c372>] direct_entry+0xc0/0x10a [<ffffffe000439f86>] full_proxy_write+0x42/0x6a [<ffffffe000309626>] vfs_write+0x7e/0x214 [<ffffffe00030992a>] ksys_write+0x98/0xc0 [<ffffffe000309960>] sys_write+0xe/0x16 [<ffffffe0002014bc>] ret_from_syscall+0x0/0x2 ---[ end trace 61917f3d9a9fadcd ]--- Signed-off-by: Chen Huang <chenhuang5@huawei.com> --- arch/riscv/kernel/stacktrace.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)