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arm64: convert syscall trace logic to C

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Currently syscall tracing is a tricky assembly state machine, which can
be rather difficult to follow, and even harder to modify. Before we
start fiddling with it for pt_regs syscalls, let's convert it to C.

This is not intended to have any functional change.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Mark Rutland 2018-07-11 14:56:44 +01:00 • committed by Will Deacon
parent 4141c857fd
commit f37099b699
2 changed files with 56 additions and 56 deletions
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57
arch/arm64/kernel/syscall.c
View file

@ -1,11 +1,15 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>
#include <linux/context_tracking.h>
#include <linux/errno.h>
#include <linux/nospec.h>
#include <linux/ptrace.h>
#include <linux/syscalls.h>
#include <asm/daifflags.h>
#include <asm/syscall.h>
#include <asm/thread_info.h>
long compat_arm_syscall(struct pt_regs *regs);
@ -29,9 +33,9 @@ static long __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn)
regs->regs[3], regs->regs[4], regs->regs[5]);
}
asmlinkage void invoke_syscall(struct pt_regs *regs, unsigned int scno,
unsigned int sc_nr,
const syscall_fn_t syscall_table[])
static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
unsigned int sc_nr,
const syscall_fn_t syscall_table[])
{
long ret;
@ -45,3 +49,50 @@ asmlinkage void invoke_syscall(struct pt_regs *regs, unsigned int scno,
regs->regs[0] = ret;
}
static inline bool has_syscall_work(unsigned long flags)
{
return unlikely(flags & _TIF_SYSCALL_WORK);
}
int syscall_trace_enter(struct pt_regs *regs);
void syscall_trace_exit(struct pt_regs *regs);
asmlinkage void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
const syscall_fn_t syscall_table[])
{
unsigned long flags = current_thread_info()->flags;
regs->orig_x0 = regs->regs[0];
regs->syscallno = scno;
local_daif_restore(DAIF_PROCCTX);
user_exit();
if (has_syscall_work(flags)) {
/* set default errno for user-issued syscall(-1) */
if (scno == NO_SYSCALL)
regs->regs[0] = -ENOSYS;
scno = syscall_trace_enter(regs);
if (scno == NO_SYSCALL)
goto trace_exit;
}
invoke_syscall(regs, scno, sc_nr, syscall_table);
/*
* The tracing status may have changed under our feet, so we have to
* check again. However, if we were tracing entry, then we always trace
* exit regardless, as the old entry assembly did.
*/
if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
local_daif_mask();
flags = current_thread_info()->flags;
if (!has_syscall_work(flags))
return;
local_daif_restore(DAIF_PROCCTX);
}
trace_exit:
syscall_trace_exit(regs);
}