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riscv: kprobes: Prevent probes in breakpoint handlers

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The ftrace selftest multiple_kprobes.tc registers kprobe events on
the first 256 text symbols from /proc/kallsyms. If handle_break() is
selected as a probe target on RISC-V, the breakpoint exception path
can trap again before it reaches the kprobe breakpoint handler. That
recursively enters do_trap_break() and can make the system
unresponsive.

Mark handle_break() and its local probe dispatch helpers as nokprobe
symbols so they are added to the kprobe blacklist, matching other
low-level breakpoint exception paths.

Signed-off-by: Rui Qi <qirui.001@bytedance.com>
Reviewed-by: Nam Cao <namcao@linutronix.de>
Link: https://patch.msgid.link/20260806043807.2583001-1-qirui.001@bytedance.com
Signed-off-by: Paul Walmsley <pjw@kernel.org>
This commit is contained in:
Rui Qi 2026-08-07 19:24:33 -06:00 committed by Paul Walmsley
parent 7655525298
commit e7d8ea6c6d
1 changed files with 3 additions and 0 deletions
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3
arch/riscv/kernel/traps.c
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@ -270,6 +270,7 @@ static bool probe_single_step_handler(struct pt_regs *regs)
return user ? uprobe_single_step_handler(regs) : kprobe_single_step_handler(regs);
}
NOKPROBE_SYMBOL(probe_single_step_handler);
static bool probe_breakpoint_handler(struct pt_regs *regs)
{
@ -277,6 +278,7 @@ static bool probe_breakpoint_handler(struct pt_regs *regs)
return user ? uprobe_breakpoint_handler(regs) : kprobe_breakpoint_handler(regs);
}
NOKPROBE_SYMBOL(probe_breakpoint_handler);
void handle_break(struct pt_regs *regs)
{
@ -301,6 +303,7 @@ void handle_break(struct pt_regs *regs)
else
die(regs, "Kernel BUG");
}
NOKPROBE_SYMBOL(handle_break);
asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
{