@@ -18,7 +18,8 @@ arm64-obj-y := debug-monitors.o entry.o irq.o fpsimd.o \
hyp-stub.o psci.o cpu_ops.o insn.o \
return_address.o cpuinfo.o cpu_errata.o \
cpufeature.o alternative.o cacheinfo.o \
- smp.o smp_spin_table.o topology.o smccc-call.o
+ smp.o smp_spin_table.o topology.o smccc-call.o \
+ syscall.o
extra-$(CONFIG_EFI) := efi-entry.o
@@ -903,7 +903,6 @@ ENDPROC(el0_error)
*/
ret_fast_syscall:
disable_daif
- str x0, [sp, #S_X0] // returned x0
ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for syscall tracing
and x2, x1, #_TIF_SYSCALL_WORK
cbnz x2, ret_fast_syscall_trace
@@ -976,15 +975,11 @@ el0_svc_naked: // compat entry point
tst x16, #_TIF_SYSCALL_WORK // check for syscall hooks
b.ne __sys_trace
- cmp wscno, wsc_nr // check upper syscall limit
- b.hs ni_sys
- mask_nospec64 xscno, xsc_nr, x19 // enforce bounds for syscall number
- ldr x16, [stbl, xscno, lsl #3] // address in the syscall table
- blr x16 // call sys_* routine
- b ret_fast_syscall
-ni_sys:
mov x0, sp
- bl do_ni_syscall
+ mov w1, wscno
+ mov w2, wsc_nr
+ mov x3, stbl
+ bl invoke_syscall
b ret_fast_syscall
ENDPROC(el0_svc)
@@ -1001,29 +996,18 @@ __sys_trace:
bl syscall_trace_enter
cmp w0, #NO_SYSCALL // skip the syscall?
b.eq __sys_trace_return_skipped
- mov wscno, w0 // syscall number (possibly new)
- mov x1, sp // pointer to regs
- cmp wscno, wsc_nr // check upper syscall limit
- b.hs __ni_sys_trace
- ldp x0, x1, [sp] // restore the syscall args
- ldp x2, x3, [sp, #S_X2]
- ldp x4, x5, [sp, #S_X4]
- ldp x6, x7, [sp, #S_X6]
- ldr x16, [stbl, xscno, lsl #3] // address in the syscall table
- blr x16 // call sys_* routine
-__sys_trace_return:
- str x0, [sp, #S_X0] // save returned x0
+ mov x0, sp
+ mov w1, wscno
+ mov w2, wsc_nr
+ mov x3, stbl
+ bl invoke_syscall
+
__sys_trace_return_skipped:
mov x0, sp
bl syscall_trace_exit
b ret_to_user
-__ni_sys_trace:
- mov x0, sp
- bl do_ni_syscall
- b __sys_trace_return
-
.popsection // .entry.text
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
new file mode 100644
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/nospec.h>
+#include <linux/ptrace.h>
+
+long do_ni_syscall(struct pt_regs *regs);
+
+typedef long (*syscall_fn_t)(unsigned long, unsigned long,
+ unsigned long, unsigned long,
+ unsigned long, unsigned long);
+
+static void __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn)
+{
+ regs->regs[0] = syscall_fn(regs->regs[0], regs->regs[1],
+ regs->regs[2], regs->regs[3],
+ regs->regs[4], regs->regs[5]);
+}
+
+asmlinkage void invoke_syscall(struct pt_regs *regs, unsigned int scno,
+ unsigned int sc_nr,
+ syscall_fn_t syscall_table[])
+{
+ if (scno < sc_nr) {
+ syscall_fn_t syscall_fn;
+ syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)];
+ __invoke_syscall(regs, syscall_fn);
+ } else {
+ regs->regs[0] = do_ni_syscall(regs);
+ }
+}
As a first step towards invoking syscalls with a pt_regs argument, convert the raw syscall invocation logic to C. We end up with a bit more register shuffling, but the unified invocation logic means we can unify the tracing paths, too. Previously, assembly had to open-code calls to ni_sys() when the system call number was out-of-bounds for the relevant syscall table. This case is now handled by invoke_syscall(), and the assembly no longer need to handle this case explicitly. This allows the tracing paths to be simplfiied and unified, as we no longer need the __ni_sys_trace path and the __sys_trace_return label. This only converts the invocation of the syscall. The rest of the syscall triage and tracing is left in assembly for now, and will be converted in subsequent patches. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> --- arch/arm64/kernel/Makefile | 3 ++- arch/arm64/kernel/entry.S | 36 ++++++++++-------------------------- arch/arm64/kernel/syscall.c | 30 ++++++++++++++++++++++++++++++ 3 files changed, 42 insertions(+), 27 deletions(-) create mode 100644 arch/arm64/kernel/syscall.c -- 2.11.0