From: Florian Bezdeka <florian.bezdeka@siemens.com>
To: xenomai@lists.linux.dev
Cc: jan.kiszka@siemens.com, rpm@xenomai.org,
Florian Bezdeka <florian.bezdeka@siemens.com>,
Clara Kowalsky <clara.kowalsky@siemens.com>
Subject: [PATCH] arm64: dovetail: Fix undefinstr/break trap handling
Date: Fri, 25 Aug 2023 14:58:44 +0200 [thread overview]
Message-ID: <20230825125844.588598-1-florian.bezdeka@siemens.com> (raw)
When running an compat RT application on arm64 the break trap is
handled via the undefined instruction trap.
A possible call stack looks like this:
Call trace:
handle_inband_event+0x2d0/0x320
inband_event_notify+0x28/0x50
signal_wake_up_state+0x7c/0xa4
complete_signal+0x104/0x2d0
__send_signal_locked+0x1d0/0x3e4
send_signal_locked+0xf0/0x140
force_sig_info_to_task+0xa0/0x164
force_sig_fault+0x64/0x94
arm64_force_sig_fault+0x48/0x80
send_user_sigtrap+0x50/0x8c
aarch32_break_handler+0xac/0x1d0
do_undefinstr+0x6c/0x360
el0_undef+0x4c/0xd0
el0t_32_sync_handler+0xd0/0x140
el0t_32_sync+0x190/0x194
The trap is never reported to the companion core at that stage so
running_oob() in do_undefinstr() will always return true. As the
following bailout happens before calling the compat breakpoint
detection (aarch32_break_handler()) debugging the compat
application does not work.
In addition aarch32_break_handler() has to report the trap entry to the
companion core.
Reported-by: Clara Kowalsky <clara.kowalsky@siemens.com>
Tested-by: Clara Kowalsky <clara.kowalsky@siemens.com>
Signed-off-by: Florian Bezdeka <florian.bezdeka@siemens.com>
---
arch/arm64/kernel/debug-monitors.c | 3 +++
arch/arm64/kernel/traps.c | 7 -------
2 files changed, 3 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 32271ed24ef5..ef7ac042a0a6 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -373,7 +373,10 @@ int aarch32_break_handler(struct pt_regs *regs)
if (!bp)
return -EFAULT;
+ mark_trap_entry(ARM64_TRAP_UNDI, regs);
send_user_sigtrap(TRAP_BRKPT);
+ mark_trap_exit(ARM64_TRAP_UNDI, regs);
+
return 0;
}
NOKPROBE_SYMBOL(aarch32_break_handler);
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index cc68be400244..9bf2f309248f 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -489,13 +489,6 @@ void arm64_notify_segfault(unsigned long addr)
void do_undefinstr(struct pt_regs *regs, unsigned long esr)
{
- /*
- * If the companion core did not switched us to in-band
- * context, we may assume that it has handled the trap.
- */
- if (running_oob())
- return;
-
/* check for AArch32 breakpoint instructions */
if (!aarch32_break_handler(regs))
return;
--
2.39.2
next reply other threads:[~2023-08-25 18:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-25 12:58 Florian Bezdeka [this message]
2023-08-28 12:33 ` [PATCH] arm64: dovetail: Fix undefinstr/break trap handling Jan Kiszka
2023-08-28 12:52 ` Florian Bezdeka
2023-08-28 13:04 ` Jan Kiszka
2023-08-28 14:36 ` Philippe Gerum
2023-08-29 7:42 ` Florian Bezdeka
2023-09-01 13:29 ` Philippe Gerum
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