The direct-call syscall dispatch function doesn't know that the exit()
and exit_group() syscall handlers don't return, so the call sites aren't
optimized accordingly.
Fix that by marking the exit syscall declarations __noreturn.
Fixes the following warnings:
vmlinux.o: warning: objtool: x64_sys_call+0x2804: __x64_sys_exit() is missing a __noreturn annotation
vmlinux.o: warning: objtool: ia32_sys_call+0x29b6: __ia32_sys_exit_group() is missing a __noreturn annotation
Fixes: 1e3ad78334 ("x86/syscall: Don't force use of indirect calls for system calls")
Closes: https://lkml.kernel.org/lkml/6dba9b32-db2c-4e6d-9500-7a08852f17a3@paulmck-laptop
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/5d8882bc077d8eadcc7fd1740b56dfb781f12288.1719381528.git.jpoimboe@kernel.org
Make <asm/syscall.h> build a switch statement instead, and the compiler can
either decide to generate an indirect jump, or - more likely these days due
to mitigations - just a series of conditional branches.
Yes, the conditional branches also have branch prediction, but the branch
prediction is much more controlled, in that it just causes speculatively
running the wrong system call (harmless), rather than speculatively running
possibly wrong random less controlled code gadgets.
This doesn't mitigate other indirect calls, but the system call indirection
is the first and most easily triggered case.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
This is a follow-up cleanup after switching to the generic syscalltbl.sh.
The old x86 specific script skipped non-existing syscalls. So, the
generated syscalls_64.h, for example, had a big hole in the syscall numbers
335-423 range. That is why there exists [0 ... __NR_*_syscall_max] =
&__*_sys_ni_cyscall.
The new script, scripts/syscalltbl.sh automatically fills holes
with __SYSCALL(<nr>, sys_ni_syscall), hence such ugly code can
go away. The designated initializers, '[nr] =' are also unneeded.
Also, there is no need to give __NR_*_syscall_max+1 because the array
size is implied by the number of syscalls in the generated headers.
Hence, there is no need to include <asm/unistd.h>, either.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210517073815.97426-4-masahiroy@kernel.org
Many architectures duplicate similar shell scripts.
Convert x86 and UML to use scripts/syscalltbl.sh. The generic script
generates seperate headers for x86/64 and x86/x32 syscalls, while the x86
specific script coalesced them into one. Adjust the code accordingly.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210517073815.97426-3-masahiroy@kernel.org
The SYSCALL macros are mapped to symbols as follows:
__SYSCALL_COMMON(nr, sym) --> __x64_<sym>
__SYSCALL_X32(nr, sym) --> __x32_<sym>
Originally, the syscalls in the x32 special range (512-547) were all
compat.
This assumption is now broken after the following commits:
55db9c0e85 ("net: remove compat_sys_{get,set}sockopt")
5f764d624a ("fs: remove the compat readv/writev syscalls")
598b3cec83 ("fs: remove compat_sys_vmsplice")
c3973b401e ("mm: remove compat_process_vm_{readv,writev}")
Those commits redefined __x32_sys_* to __x64_sys_* because there is no stub
like __x32_sys_*.
Defining them as follows is more sensible and cleaner.
__SYSCALL_COMMON(nr, sym) --> __x64_<sym>
__SYSCALL_X32(nr, sym) --> __x64_<sym>
This works because both x86_64 and x32 use the same ABI (RDI, RSI, RDX,
R10, R8, R9)
The ugly #define __x32_sys_* will go away.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210517073815.97426-2-masahiroy@kernel.org
Now that import_iovec handles compat iovecs, the native syscalls
can be used for the compat case as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Now that import_iovec handles compat iovecs, the native vmsplice syscall
can be used for the compat case as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Now that import_iovec handles compat iovecs, the native readv and writev
syscalls can be used for the compat case as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Now that the ->compat_{get,set}sockopt proto_ops methods are gone
there is no good reason left to keep the compat syscalls separate.
This fixes the odd use of unsigned int for the compat_setsockopt
optlen and the missing sock_use_custom_sol_socket.
It would also easily allow running the eBPF hooks for the compat
syscalls, but such a large change in behavior does not belong into
a consolidation patch like this one.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
asmlinkage is no longer required since the syscall ABI is now fully under
x86 architecture control. This makes the 32-bit native syscalls a bit more
effecient by passing in regs via EAX instead of on the stack.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200313195144.164260-18-brgerst@gmail.com
Move the ABI prefixes to the __SYSCALL_[abi]() macros. This allows removal
of the need to strip the prefix for UML.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-13-brgerst@gmail.com
Syscall qualifier support is no longer needed.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-11-brgerst@gmail.com
Instead of using an array in asm-offsets to calculate the max syscall
number, calculate it when writing out the syscall headers.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-9-brgerst@gmail.com
Since X32 has its own syscall table now, move it to a separate file.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-8-brgerst@gmail.com
