https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=246215
Bug ID: 246215
Summary: [rtld] fails for i386 on amd64 if auxv does not
contain PAGESIZES
Product: Base System
Version: 12.1-RELEASE
Hardware: amd64
OS: Any
Status: New
Severity: Affects Only Me
Priority: ---
Component: kern
Assignee: b...@freebsd.org
Reporter: pa...@free.fr
I came across this issue whilst working on getting Valgrind to work.
When Valgrind runs, the guest application is loaded by Valgrind rather than the
usual FreeBSD mechanisms. Thus Valgrind will synthesize an auxv, mmap rtld and
run the rtld text in Valgrind's JIT compiled virtual CPU. However, to avoid
memory space issues between the host and the guest, Valgrind does not provide
auxv entries that contain pointers. This includes PAGESIZES.
Normally rtld obtains the pagesizes from auxv, but it has fallback code to use
syscalls. This works OK for an amd64 exe on an amd64 kernel and i386 on i386.
But there is a problem for i386 on amd64. The i386 application will see
MAXPAGESLEN as 3 from the amd64 headers. But the i386 kernel sees this as only
2 [I might have gotten this the wrong way around]. The sysctl copy out code
sees this discrepancy and sets ENOMEM and the application terminates without
finishing the execution of rtld.
(I analysed all this with dtrace and looking at the source code, I don't know
how to use gdb/lldb to step through rtld code).
--
You are receiving this mail because:
You are the assignee for the bug.
_______________________________________________
freebsd-bugs@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-bugs
To unsubscribe, send any mail to "freebsd-bugs-unsubscr...@freebsd.org"
