On October 28, 2025 11:54:43 PM PDT, Brian Gerst <[email protected]> wrote: >On Sun, Oct 26, 2025 at 6:12 PM H. Peter Anvin <[email protected]> wrote: >> >> There is no fundamental reason for the int80_landing_pad symbol. If ip >> falls within the vdso, and the vdso is moved, we should change the ip >> accordingly, regardless of mode or location within the vdso. This >> *currently* can only happen on 32 bits, but there isn't any reason not >> to do so generically. >> >> Note that if this is ever possible from a vdso-internal call, then the >> user space stack will also needed to be adjusted (as well as the >> shadow stack, if enabled.) Fortunately this is not currently the case. >> >> At the moment, we don't even consider other threads when moving the >> vdso. The assumption is that it is only used by process freeze/thaw >> for migration, where this is not an issue. >> >> Signed-off-by: H. Peter Anvin (Intel) <[email protected]> >> --- >> arch/x86/entry/vdso/vdso32/system_call.S | 1 - >> arch/x86/entry/vdso/vma.c | 16 ++++++---------- >> arch/x86/tools/vdso2c.c | 1 - >> 3 files changed, 6 insertions(+), 12 deletions(-) >> >> diff --git a/arch/x86/entry/vdso/vdso32/system_call.S >> b/arch/x86/entry/vdso/vdso32/system_call.S >> index 2a15634bbe75..d14eca4403c5 100644 >> --- a/arch/x86/entry/vdso/vdso32/system_call.S >> +++ b/arch/x86/entry/vdso/vdso32/system_call.S >> @@ -62,7 +62,6 @@ __kernel_vsyscall: >> >> /* Enter using int $0x80 */ >> int $0x80 >> -SYM_INNER_LABEL(int80_landing_pad, SYM_L_GLOBAL) > >This is still needed by do_fast_syscall_32(). > > >Brian Gerst >
Yeah, that was a complete brainfart on my part. I'm already reworking the patchset, fixing this and adding more improvements.
