diff options
| author | Andy Lutomirski <luto@kernel.org> | 2015-10-05 17:48:08 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-10-09 09:41:08 +0200 |
| commit | bd2d3a3ba67ac580f6e809aac36bf942f5447f91 (patch) | |
| tree | acebe9fe2bda6efe2ccbfea2cf52c1fcf10b1337 /arch/x86/entry/common.c | |
| parent | eb974c62565072e10c1422eb3205f5b611dd99a1 (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/common.c')
| -rw-r--r-- | arch/x86/entry/common.c | 43 |
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 |