[PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag
From: Christoph Hellwig <hch@lst.de>
Date: 2020-09-18 12:47:55
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
Subsystem:
filesystems (vfs and infrastructure), scheduler, sparc + ultrasparc (sparc/sparc64), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Alexander Viro, Christian Brauner, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, "David S. Miller", Andreas Larsson, Linus Torvalds, Thomas Gleixner, Borislav Petkov, Dave Hansen
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); } #define in_compat_syscall in_compat_syscall #endif
diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index d4edf281fff49d..fbab072d4e5b31 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h@@ -208,7 +208,7 @@ static inline bool in_32bit_syscall(void) #ifdef CONFIG_COMPAT static inline bool in_compat_syscall(void) { - return in_32bit_syscall(); + return in_32bit_syscall() || (current->flags & PF_FORCE_COMPAT); } #define in_compat_syscall in_compat_syscall /* override the generic impl */ #endif
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 3790c7fe9fee22..5755d557c3f7bc 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c@@ -5449,6 +5449,9 @@ static int io_req_defer_prep(struct io_kiocb *req, if (unlikely(ret)) return ret; + if (req->ctx->compat) + current->flags |= PF_FORCE_COMPAT; + switch (req->opcode) { case IORING_OP_NOP: break;
@@ -5546,6 +5549,7 @@ static int io_req_defer_prep(struct io_kiocb *req, break; } + current->flags &= ~PF_FORCE_COMPAT; return ret; }
@@ -5669,6 +5673,9 @@ static int io_issue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe, struct io_ring_ctx *ctx = req->ctx; int ret; + if (ctx->compat) + current->flags |= PF_FORCE_COMPAT; + switch (req->opcode) { case IORING_OP_NOP: ret = io_nop(req, cs);
@@ -5898,6 +5905,8 @@ static int io_issue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe, break; } + current->flags &= ~PF_FORCE_COMPAT; + if (ret) return ret;
diff --git a/include/linux/compat.h b/include/linux/compat.h
index b354ce58966e2d..685066f7ad325f 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h@@ -891,7 +891,10 @@ asmlinkage long compat_sys_socketcall(int call, u32 __user *args); */ #ifndef in_compat_syscall -static inline bool in_compat_syscall(void) { return is_compat_task(); } +static inline bool in_compat_syscall(void) +{ + return is_compat_task() || (current->flags & PF_FORCE_COMPAT); +} #endif /**
diff --git a/include/linux/sched.h b/include/linux/sched.h
index afe01e232935fa..c8b183b5655a1e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h@@ -1491,6 +1491,7 @@ extern struct pid *cad_pid; */ #define PF_IDLE 0x00000002 /* I am an IDLE thread */ #define PF_EXITING 0x00000004 /* Getting shut down */ +#define PF_FORCE_COMPAT 0x00000008 /* acting as compat task */ #define PF_VCPU 0x00000010 /* I'm a virtual CPU */ #define PF_WQ_WORKER 0x00000020 /* I'm a workqueue worker */ #define PF_FORKNOEXEC 0x00000040 /* Forked but didn't exec */
--
2.28.0