We need to set up the LSTAR MSR and friends on each processor - it is not
enough to do it on processor 0. Otherwise, a system call instruction will
always fails if happens to run on any vcpu other than the first one.
With this patch, tst-syscall now passes on my machine with the release
compilation, on both single vcpu (run.py -c1) and many (-c4).
With debug build, the patch still fails - I have other fixes to make it
work.
Refs #791.
Signed-off-by: Nadav Har'El <n...@scylladb.com>
---
arch/x64/arch-cpu.hh | 2 ++
arch/x64/processor.hh | 2 ++
arch/x64/arch-setup.cc | 6 +++---
3 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/x64/arch-cpu.hh b/arch/x64/arch-cpu.hh
index 808ff2a..b1cb0bf 100644
--- a/arch/x64/arch-cpu.hh
+++ b/arch/x64/arch-cpu.hh
@@ -174,6 +174,8 @@ inline void arch_cpu::init_on_cpu()
// We can't trust the FPU and the MXCSR to be always initialized to
default values.
// In at least one particular version of Xen it is not, leading to SIMD
exceptions.
processor::init_fpu();
+
+ processor::init_syscall();
}
struct exception_guard {
diff --git a/arch/x64/processor.hh b/arch/x64/processor.hh
index 89bc9fc..250153b 100644
--- a/arch/x64/processor.hh
+++ b/arch/x64/processor.hh
@@ -394,6 +394,8 @@ inline void init_fpu()
asm volatile ("ldmxcsr %0" : : "m" (csr));
}
+void init_syscall();
+
inline void lfence()
{
asm volatile("lfence");
diff --git a/arch/x64/arch-setup.cc b/arch/x64/arch-setup.cc
index 0994de5..0fabfec 100644
--- a/arch/x64/arch-setup.cc
+++ b/arch/x64/arch-setup.cc
@@ -224,8 +224,8 @@ static const int CS_SELECTOR_SHIFT = 3;
// syscall shift
static const int IA_32_STAR_SYSCALL_SHIFT = 32;
-static void setup_syscall()
-{
+namespace processor {
+void init_syscall() {
unsigned long cs = gdt_cs;
processor::wrmsr(msr::IA32_STAR, (cs << CS_SELECTOR_SHIFT) <<
IA_32_STAR_SYSCALL_SHIFT);
// lstar is where syscall set rip so we set it to syscall_entry
@@ -236,6 +236,7 @@ static void setup_syscall()
processor::wrmsr(msr::IA32_FMASK, 0);
processor::wrmsr(msr::IA32_EFER, processor::rdmsr(msr::IA32_EFER) |
IA32_EFER_SCE);
}
+}
void arch_init_premain()
{
@@ -244,7 +245,6 @@ void arch_init_premain()
debug_early_u64("Error reading disk (real mode): ",
static_cast<u64>(omb.disk_err));
disable_pic();
- setup_syscall();
}
#include "drivers/driver.hh"
--
2.7.4
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