summaryrefslogtreecommitdiff
path: root/arch/x86/entry/common.c
diff options
context:
space:
mode:
authorDominik Brodowski <linux@dominikbrodowski.net>2018-04-05 12:53:04 +0300
committerIngo Molnar <mingo@kernel.org>2018-04-05 17:59:38 +0300
commitebeb8c82ffaf94435806ff0b686fffd41dd410b5 (patch)
tree27e14910bb529a9e146949a9ea0563012bca2ea0 /arch/x86/entry/common.c
parent7303e30ec1d8fb5ca1f07c92d069241c32b2ee1b (diff)
downloadlinux-ebeb8c82ffaf94435806ff0b686fffd41dd410b5.tar.xz
syscalls/x86: Use 'struct pt_regs' based syscall calling for IA32_EMULATION and x32
Extend ARCH_HAS_SYSCALL_WRAPPER for i386 emulation and for x32 on 64-bit x86. For x32, all we need to do is to create an additional stub for each compat syscall which decodes the parameters in x86-64 ordering, e.g.: asmlinkage long __compat_sys_x32_xyzzy(struct pt_regs *regs) { return c_SyS_xyzzy(regs->di, regs->si, regs->dx); } For i386 emulation, we need to teach compat_sys_*() to take struct pt_regs as its only argument, e.g.: asmlinkage long __compat_sys_ia32_xyzzy(struct pt_regs *regs) { return c_SyS_xyzzy(regs->bx, regs->cx, regs->dx); } In addition, we need to create additional stubs for common syscalls (that is, for syscalls which have the same parameters on 32-bit and 64-bit), e.g.: asmlinkage long __sys_ia32_xyzzy(struct pt_regs *regs) { return c_sys_xyzzy(regs->bx, regs->cx, regs->dx); } This approach avoids leaking random user-provided register content down the call chain. This patch is based on an original proof-of-concept | From: Linus Torvalds <torvalds@linux-foundation.org> | Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> and was split up and heavily modified by me, in particular to base it on ARCH_HAS_SYSCALL_WRAPPER. Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180405095307.3730-6-linux@dominikbrodowski.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry/common.c')
-rw-r--r--arch/x86/entry/common.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index e1b91bffa988..425f798b39e3 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -325,6 +325,9 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs)
if (likely(nr < IA32_NR_syscalls)) {
nr = array_index_nospec(nr, IA32_NR_syscalls);
+#ifdef CONFIG_SYSCALL_PTREGS
+ regs->ax = ia32_sys_call_table[nr](regs);
+#else
/*
* It's possible that a 32-bit syscall implementation
* takes a 64-bit parameter but nonetheless assumes that
@@ -335,6 +338,7 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs)
(unsigned int)regs->bx, (unsigned int)regs->cx,
(unsigned int)regs->dx, (unsigned int)regs->si,
(unsigned int)regs->di, (unsigned int)regs->bp);
+#endif /* CONFIG_SYSCALL_PTREGS */
}
syscall_return_slowpath(regs);