Date: Mon, 18 Sep 2023 13:34:52 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 273929] AArch64 machine-dependent code clobbers X0 in SIGTRAP from capsicum violations Message-ID: <bug-273929-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=273929 Bug ID: 273929 Summary: AArch64 machine-dependent code clobbers X0 in SIGTRAP from capsicum violations Product: Base System Version: CURRENT Hardware: arm64 OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: theraven@FreeBSD.org X0 is used as both the first argument register and as the return value. If SIGTRAP is delivered to a process for a Capsicum violation, the mcontext_t in the signal should contain the arguments so that software can trap and emulate the system calls. This works on x86[-64] but on AArch64 X0 is overwritten before the system call handler is entered. When emulating `open`, for example, the signal frame always sees the path as `(char*)94`, which makes this impossible. It would be nice if this could be fixed before 14.0 or be subject to an EN afterwards, since it makes capsicum trap-and-emulate behaviour unusable currently. -- You are receiving this mail because: You are the assignee for the bug.help
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