[RFC][PATCH v2 01/21] x86/syscall: Add wrapper for invoking syscall function

Alexandre Chartre
2020-11-16T14:46:42Z

Add a wrapper function for invoking a syscall function.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
arch/x86/entry/common.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 870efeec8bda..d222212908ad 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -35,6 +35,15 @@
#include <asm/syscall.h>
#include <asm/irq_stack.h>

+static __always_inline void run_syscall(sys_call_ptr_t sysfunc,
+ struct pt_regs *regs)
+{
+ if (!sysfunc)
+ return;
+
+ regs->ax = sysfunc(regs);
+}
+
#ifdef CONFIG_X86_64
__visible noinstr void do_syscall_64(unsigned long nr, struct pt_regs *regs)
{
@@ -43,15 +52,16 @@ __visible noinstr void do_syscall_64(unsigned long nr, struct pt_regs *regs)
instrumentation_begin();
if (likely(nr < NR_syscalls)) {
nr = array_index_nospec(nr, NR_syscalls);
- regs->ax = sys_call_table[nr](regs);
+ run_syscall(sys_call_table[nr], regs);
#ifdef CONFIG_X86_X32_ABI
} else if (likely((nr & __X32_SYSCALL_BIT) &&
(nr & ~__X32_SYSCALL_BIT) < X32_NR_syscalls)) {
nr = array_index_nospec(nr & ~__X32_SYSCALL_BIT,
X32_NR_syscalls);
- regs->ax = x32_sys_call_table[nr](regs);
+ run_syscall(x32_sys_call_table[nr], regs);
#endif
}
+
instrumentation_end();
syscall_exit_to_user_mode(regs);
}
@@ -75,7 +85,7 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs,
if (likely(nr < IA32_NR_syscalls)) {
instrumentation_begin();
nr = array_index_nospec(nr, IA32_NR_syscalls);
- regs->ax = ia32_sys_call_table[nr](regs);
+ run_syscall(ia32_sys_call_table[nr], regs);
instrumentation_end();
}
}
--
2.18.4