Date: Tue, 4 May 2021 14:21:20 GMT From: Edward Tomasz Napierala <trasz@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 023bff799098 - main - linux(4): fix ptrace(2) to properly handle orig_rax Message-ID: <202105041421.144ELKUq076332@gitrepo.freebsd.org>
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The branch main has been updated by trasz: URL: https://cgit.FreeBSD.org/src/commit/?id=023bff799098cac28732f2800c967f0248d2eb47 commit 023bff799098cac28732f2800c967f0248d2eb47 Author: Edward Tomasz Napierala <trasz@FreeBSD.org> AuthorDate: 2021-05-04 13:11:01 +0000 Commit: Edward Tomasz Napierala <trasz@FreeBSD.org> CommitDate: 2021-05-04 14:21:06 +0000 linux(4): fix ptrace(2) to properly handle orig_rax This fixes strace(1) erroneously reporting return values as "Function not implemented", combined with reporting the binary ABI as X32. Very similar code in linux_ptrace_getregs() is left as it is - it's probably wrong too, but I don't have a way to test it. Sponsored By: EPSRC Differential Revision: https://reviews.freebsd.org/D29927 --- sys/amd64/linux/linux_ptrace.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/sys/amd64/linux/linux_ptrace.c b/sys/amd64/linux/linux_ptrace.c index 76ad9b1e25c4..43ecd8892e0f 100644 --- a/sys/amd64/linux/linux_ptrace.c +++ b/sys/amd64/linux/linux_ptrace.c @@ -506,18 +506,18 @@ linux_ptrace_getregset_prstatus(struct thread *td, pid_t pid, l_ulong data) } if (lwpinfo.pl_flags & PL_FLAG_SCE) { /* - * The strace(1) utility depends on RAX being set to -ENOSYS - * on syscall entry; otherwise it loops printing those: - * - * [ Process PID=928 runs in 64 bit mode. ] - * [ Process PID=928 runs in x32 mode. ] + * Undo the mangling done in exception.S:fast_syscall_common(). */ - l_regset.rax = -38; /* -ENOSYS */ + l_regset.r10 = l_regset.rcx; + } + if (lwpinfo.pl_flags & (PL_FLAG_SCE | PL_FLAG_SCX)) { /* - * Undo the mangling done in exception.S:fast_syscall_common(). + * In Linux, the syscall number - passed to the syscall + * as rax - is preserved in orig_rax; rax gets overwritten + * with syscall return value. */ - l_regset.r10 = l_regset.rcx; + l_regset.orig_rax = lwpinfo.pl_syscall_code; } len = MIN(iov.iov_len, sizeof(l_regset));
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