diff options
| author | Andy Lutomirski <luto@kernel.org> | 2015-10-05 17:48:10 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-10-09 09:41:09 +0200 |
| commit | 710246df58041106b7de645f4b45770f8a59a269 (patch) | |
| tree | 2a6809135079d9ff4854620f966c16a8dee69aef | |
| parent | ee08c6bd315e70756ad2c47ee6ea708a4a882b55 (diff) | |
| download | linux-710246df58041106b7de645f4b45770f8a59a269.tar.bz2 | |
x86/entry: Add C code for fast system call entries
This handles both SYSENTER and SYSCALL. The asm glue will take
care of the differences.
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/6041a58a9b8ef6d2522ab4350deb1a1945eb563f.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -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 41d17508cf46..1b2606edc621 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -24,6 +24,8 @@ #include <asm/desc.h> #include <asm/traps.h> +#include <asm/vdso.h> +#include <asm/uaccess.h> #define CREATE_TRACE_POINTS #include <trace/events/syscalls.h> @@ -360,4 +362,45 @@ __visible void do_int80_syscall_32(struct pt_regs *regs) syscall_return_slowpath(regs); } + +__visible void do_fast_syscall_32(struct pt_regs *regs) +{ + /* + * Called using the internal vDSO SYSENTER/SYSCALL32 calling + * convention. Adjust regs so it looks like we entered using int80. + */ + + unsigned long landing_pad = (unsigned long)current->mm->context.vdso + + vdso_image_32.sym_int80_landing_pad; + + /* + * SYSENTER loses EIP, and even SYSCALL32 needs us to skip forward + * so that 'regs->ip -= 2' lands back on an int $0x80 instruction. + * Fix it up. + */ + regs->ip = landing_pad; + + /* + * Fetch ECX from where the vDSO stashed it. + * + * WARNING: We are in CONTEXT_USER and RCU isn't paying attention! + */ + local_irq_enable(); + if (get_user(*(u32 *)®s->cx, + (u32 __user __force *)(unsigned long)(u32)regs->sp)) { + /* User code screwed up. */ + local_irq_disable(); + regs->ax = -EFAULT; +#ifdef CONFIG_CONTEXT_TRACKING + enter_from_user_mode(); +#endif + prepare_exit_to_usermode(regs); + return; + } + local_irq_disable(); + + /* Now this is just like a normal syscall. */ + do_int80_syscall_32(regs); + return; +} #endif |