Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2020-09-18 13:40:36
Also in:
io-uring, keyrings, linux-arch, linux-arm-kernel, linux-block, linux-fsdevel, linux-mips, linux-mm, linux-s390, linux-scsi, linux-security-module, linuxppc-dev, lkml, sparclinux
On Fri, Sep 18, 2020 at 02:45:25PM +0200, Christoph Hellwig wrote:
quoted hunk ↗ jump to hunk
Add a flag to force processing a syscall as a compat syscall. This is required so that in_compat_syscall() works for I/O submitted by io_uring helper threads on behalf of compat syscalls. Signed-off-by: Christoph Hellwig <hch@lst.de> --- arch/sparc/include/asm/compat.h | 3 ++- arch/x86/include/asm/compat.h | 2 +- fs/io_uring.c | 9 +++++++++ include/linux/compat.h | 5 ++++- include/linux/sched.h | 1 + 5 files changed, 17 insertions(+), 3 deletions(-)diff --git a/arch/sparc/include/asm/compat.h b/arch/sparc/include/asm/compat.h index 40a267b3bd5208..fee6c51d36e869 100644 --- a/arch/sparc/include/asm/compat.h +++ b/arch/sparc/include/asm/compat.h@@ -211,7 +211,8 @@ static inline int is_compat_task(void) static inline bool in_compat_syscall(void) { /* Vector 0x110 is LINUX_32BIT_SYSCALL_TRAP */ - return pt_regs_trap_type(current_pt_regs()) == 0x110; + return pt_regs_trap_type(current_pt_regs()) == 0x110 || + (current->flags & PF_FORCE_COMPAT);
Can't say I like that approach ;-/ Reasoning about the behaviour is much harder when it's controlled like that - witness set_fs() shite...