From: Alexandre Chartre <alexandre.chartre@oracle.com>
To: "tglx@linutronix.de"@userv0122.oracle.com,
"mingo@redhat.com"@userv0122.oracle.com,
"bp@alien8.de"@userv0122.oracle.com,
"hpa@zytor.com"@userv0122.oracle.com,
"x86@kernel.org"@userv0122.oracle.com,
"dave.hansen@linux.intel.com"@userv0122.oracle.com,
"luto@kernel.org"@userv0122.oracle.com,
"peterz@infradead.org"@userv0122.oracle.com,
"linux-kernel@vger.kernel.org"@userv0122.oracle.com,
"thomas.lendacky@amd.com"@userv0122.oracle.com,
"jroedel@suse.de"@userv0122.oracle.com
Cc: "konrad.wilk@oracle.com"@userv0122.oracle.com,
"jan.setjeeilers@oracle.com"@userv0122.oracle.com,
"junaids@google.com"@userv0122.oracle.com,
"oweisse@google.com"@userv0122.oracle.com,
"rppt@linux.vnet.ibm.com"@userv0122.oracle.com,
"graf@amazon.de"@userv0122.oracle.com,
"mgross@linux.intel.com"@userv0122.oracle.com,
"kuzuno@gmail.com"@userv0122.oracle.com,
"alexandre.chartre@oracle.com"@userv0122.oracle.com
Subject: [RFC][PATCH 05/24] x86/entry: Implement ret_from_fork body with C code
Date: Mon, 9 Nov 2020 12:23:00 +0100 [thread overview]
Message-ID: <20201109112319.264511-6-alexandre.chartre@oracle.com> (raw)
In-Reply-To: <20201109112319.264511-1-alexandre.chartre@oracle.com>
ret_from_fork is a mix of assembly code and calls to C functions.
Re-implement ret_from_fork so that it calls a single C function.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
arch/x86/entry/common.c | 18 ++++++++++++++++++
arch/x86/entry/entry_64.S | 28 +++++-----------------------
2 files changed, 23 insertions(+), 23 deletions(-)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index d222212908ad..7ee15a12c115 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -35,6 +35,24 @@
#include <asm/syscall.h>
#include <asm/irq_stack.h>
+__visible noinstr void return_from_fork(struct pt_regs *regs,
+ struct task_struct *prev,
+ void (*kfunc)(void *), void *kargs)
+{
+ schedule_tail(prev);
+ if (kfunc) {
+ /* kernel thread */
+ kfunc(kargs);
+ /*
+ * A kernel thread is allowed to return here after
+ * successfully calling kernel_execve(). Exit to
+ * userspace to complete the execve() syscall.
+ */
+ regs->ax = 0;
+ }
+ syscall_exit_to_user_mode(regs);
+}
+
static __always_inline void run_syscall(sys_call_ptr_t sysfunc,
struct pt_regs *regs)
{
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 274384644b5e..73e9cd47dc83 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -276,31 +276,13 @@ SYM_FUNC_END(__switch_to_asm)
*/
.pushsection .text, "ax"
SYM_CODE_START(ret_from_fork)
- UNWIND_HINT_EMPTY
- movq %rax, %rdi
- call schedule_tail /* rdi: 'prev' task parameter */
-
- testq %rbx, %rbx /* from kernel_thread? */
- jnz 1f /* kernel threads are uncommon */
-
-2:
UNWIND_HINT_REGS
- movq %rsp, %rdi
- call syscall_exit_to_user_mode /* returns with IRQs disabled */
+ movq %rsp, %rdi /* pt_regs */
+ movq %rax, %rsi /* 'prev' task parameter */
+ movq %rbx, %rdx /* kernel thread func */
+ movq %r12, %rcx /* kernel thread arg */
+ call return_from_fork /* returns with IRQs disabled */
jmp swapgs_restore_regs_and_return_to_usermode
-
-1:
- /* kernel thread */
- UNWIND_HINT_EMPTY
- movq %r12, %rdi
- CALL_NOSPEC rbx
- /*
- * A kernel thread is allowed to return here after successfully
- * calling kernel_execve(). Exit to userspace to complete the execve()
- * syscall.
- */
- movq $0, RAX(%rsp)
- jmp 2b
SYM_CODE_END(ret_from_fork)
.popsection
--
2.18.4
next prev parent reply other threads:[~2020-11-09 11:24 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-09 11:22 [RFC][PATCH 00/24] x86/pti: Defer CR3 switch to C code Alexandre Chartre
2020-11-09 11:22 ` [RFC][PATCH 01/24] x86/syscall: Add wrapper for invoking syscall function Alexandre Chartre
2020-11-09 17:25 ` Andy Lutomirski
2020-11-09 17:45 ` Alexandre Chartre
2020-11-09 11:22 ` [RFC][PATCH 02/24] x86/entry: Update asm_call_on_stack to support more function arguments Alexandre Chartre
2020-11-09 11:22 ` [RFC][PATCH 03/24] x86/entry: Consolidate IST entry from userspace Alexandre Chartre
2020-11-09 11:22 ` [RFC][PATCH 04/24] x86/sev-es: Define a setup stack function for the VC idtentry Alexandre Chartre
2020-11-09 11:23 ` Alexandre Chartre [this message]
2020-11-09 11:23 ` [RFC][PATCH 06/24] x86/pti: Provide C variants of PTI switch CR3 macros Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 07/24] x86/entry: Fill ESPFIX stack using C code Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 08/24] x86/entry: Add C version of SWAPGS and SWAPGS_UNSAFE_STACK Alexandre Chartre
2020-11-09 17:38 ` Andy Lutomirski
2020-11-09 18:04 ` Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 09/24] x86/entry: Add C version of paranoid_entry/exit Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 10/24] x86/pti: Introduce per-task PTI trampoline stack Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 11/24] x86/pti: Function to clone page-table entries from a specified mm Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 12/24] x86/pti: Function to map per-cpu page-table entry Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 13/24] x86/pti: Extend PTI user mappings Alexandre Chartre
2020-11-09 17:28 ` Andy Lutomirski
2020-11-09 17:52 ` Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 14/24] x86/pti: Use PTI stack instead of trampoline stack Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 15/24] x86/pti: Execute syscall functions on the kernel stack Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 16/24] x86/pti: Execute IDT handlers " Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 17/24] x86/pti: Execute IDT handlers with error code " Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 18/24] x86/pti: Execute system vector handlers " Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 19/24] x86/pti: Execute page fault handler " Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 20/24] x86/pti: Execute NMI " Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 21/24] x86/entry: Disable stack-protector for IST entry C handlers Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 22/24] x86/entry: Defer paranoid entry/exit to C code Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 23/24] x86/entry: Remove paranoid_entry and paranoid_exit Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 24/24] x86/pti: Defer CR3 switch to C code for non-IST and syscall entries Alexandre Chartre
2020-11-09 14:00 ` [RFC][PATCH 00/24] x86/pti: Defer CR3 switch to C code Alexandre Chartre
2020-11-09 14:44 Alexandre Chartre
2020-11-09 14:44 ` [RFC][PATCH 05/24] x86/entry: Implement ret_from_fork body with " Alexandre Chartre
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201109112319.264511-6-alexandre.chartre@oracle.com \
--to=alexandre.chartre@oracle.com \
--cc="alexandre.chartre@oracle.com"@userv0122.oracle.com \
--cc="bp@alien8.de"@userv0122.oracle.com \
--cc="dave.hansen@linux.intel.com"@userv0122.oracle.com \
--cc="graf@amazon.de"@userv0122.oracle.com \
--cc="hpa@zytor.com"@userv0122.oracle.com \
--cc="jan.setjeeilers@oracle.com"@userv0122.oracle.com \
--cc="jroedel@suse.de"@userv0122.oracle.com \
--cc="junaids@google.com"@userv0122.oracle.com \
--cc="konrad.wilk@oracle.com"@userv0122.oracle.com \
--cc="kuzuno@gmail.com"@userv0122.oracle.com \
--cc="linux-kernel@vger.kernel.org"@userv0122.oracle.com \
--cc="luto@kernel.org"@userv0122.oracle.com \
--cc="mgross@linux.intel.com"@userv0122.oracle.com \
--cc="mingo@redhat.com"@userv0122.oracle.com \
--cc="oweisse@google.com"@userv0122.oracle.com \
--cc="peterz@infradead.org"@userv0122.oracle.com \
--cc="rppt@linux.vnet.ibm.com"@userv0122.oracle.com \
--cc="tglx@linutronix.de"@userv0122.oracle.com \
--cc="thomas.lendacky@amd.com"@userv0122.oracle.com \
--cc="x86@kernel.org"@userv0122.oracle.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).