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authorAndy Lutomirski <luto@kernel.org>2015-10-05 17:48:08 -0700
committerIngo Molnar <mingo@kernel.org>2015-10-09 09:41:08 +0200
commitbd2d3a3ba67ac580f6e809aac36bf942f5447f91 (patch)
treeacebe9fe2bda6efe2ccbfea2cf52c1fcf10b1337 /arch/x86/entry
parenteb974c62565072e10c1422eb3205f5b611dd99a1 (diff)
x86/entry: Add do_syscall_32(), a C function to do 32-bit syscalls
System calls are really quite simple. Add a helper to call a 32-bit system call. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> 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: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/a77ed179834c27da436fb4a7fb23c8ee77abc11c.1444091585.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry')
-rw-r--r--arch/x86/entry/common.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index d94a60c16029..41d17508cf46 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -318,3 +318,46 @@ __visible void syscall_return_slowpath(struct pt_regs *regs)
local_irq_disable();
prepare_exit_to_usermode(regs);
}
+
+#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
+/*
+ * Does a 32-bit syscall. Called with IRQs off and does all entry and
+ * exit work.
+ */
+__visible void do_int80_syscall_32(struct pt_regs *regs)
+{
+ struct thread_info *ti = pt_regs_to_thread_info(regs);
+ unsigned int nr = (unsigned int)regs->orig_ax;
+
+#ifdef CONFIG_IA32_EMULATION
+ ti->status |= TS_COMPAT;
+#endif
+
+ local_irq_enable();
+
+ if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY) {
+ /*
+ * Subtlety here: if ptrace pokes something larger than
+ * 2^32-1 into orig_ax, this truncates it. This may or
+ * may not be necessary, but it matches the old asm
+ * behavior.
+ */
+ nr = syscall_trace_enter(regs);
+ }
+
+ if (nr < IA32_NR_syscalls) {
+ /*
+ * It's possible that a 32-bit syscall implementation
+ * takes a 64-bit parameter but nonetheless assumes that
+ * the high bits are zero. Make sure we zero-extend all
+ * of the args.
+ */
+ regs->ax = ia32_sys_call_table[nr](
+ (unsigned int)regs->bx, (unsigned int)regs->cx,
+ (unsigned int)regs->dx, (unsigned int)regs->si,
+ (unsigned int)regs->di, (unsigned int)regs->bp);
+ }
+
+ syscall_return_slowpath(regs);
+}
+#endif