summaryrefslogtreecommitdiff
path: root/arch/x86/include/asm/vdso.h
diff options
context:
space:
mode:
authorAndy Lutomirski <luto@kernel.org>2015-10-05 17:48:01 -0700
committerIngo Molnar <mingo@kernel.org>2015-10-09 09:41:06 +0200
commit8242c6c84a644e5f0f721e4ae2bd542f640c89f9 (patch)
tree9048381769c3313271241cd3ba7f250439f6e543 /arch/x86/include/asm/vdso.h
parent7bcdea4d050cbe4912854a68b93494203eec8b24 (diff)
x86/vdso/32: Save extra registers in the INT80 vsyscall path
The goal is to integrate the SYSENTER and SYSCALL32 entry paths with the INT80 path. SYSENTER clobbers ESP and EIP. SYSCALL32 clobbers ECX (and, invisibly, R11). SYSRETL (long mode to compat mode) clobbers ECX and, invisibly, R11. SYSEXIT (which we only need for native 32-bit) clobbers ECX and EDX. This means that we'll need to provide ESP to the kernel in a register (I chose ECX, since it's only needed for SYSENTER) and we need to provide the args that normally live in ECX and EDX in memory. The epilogue needs to restore ECX and EDX, since user code relies on regs being preserved. We don't need to do anything special about EIP, since the kernel already knows where we are. The kernel will eventually need to know where int $0x80 lands, so add a vdso_image entry for it. The only user-visible effect of this code is that ptrace-induced changes to ECX and EDX during fast syscalls will be lost. This is already the case for the SYSENTER path. 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/b860925adbee2d2627a0671fbfe23a7fd04127f8.1444091584.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/vdso.h')
-rw-r--r--arch/x86/include/asm/vdso.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 5bcb1de8296e..756de9190aec 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -26,6 +26,7 @@ struct vdso_image {
long sym___kernel_sigreturn;
long sym___kernel_rt_sigreturn;
long sym___kernel_vsyscall;
+ long sym_int80_landing_pad;
};
#ifdef CONFIG_X86_64