x86, vdso: Add 32 bit VDSO time support for 32 bit kernel

This patch add the time support for 32 bit a VDSO to a 32 bit kernel.

For 32 bit programs running on a 32 bit kernel, the same mechanism is
used as for 64 bit programs running on a 64 bit kernel.

Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-10-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

6 files changed, 162 insertions, 11 deletions

diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index 7a3d13e23f25..6cef7a1b014c 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -146,8 +146,16 @@ KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS))
 $(vdso32-images:%=$(obj)/%.dbg): KBUILD_AFLAGS = $(KBUILD_AFLAGS_32)
 $(vdso32-images:%=$(obj)/%.dbg): asflags-$(CONFIG_X86_64) += -m32
 
+KBUILD_CFLAGS_32 := $(filter-out -m64,$(KBUILD_CFLAGS))
+KBUILD_CFLAGS_32 := $(filter-out -mcmodel=kernel,$(KBUILD_CFLAGS_32))
+KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32))
+KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(KBUILD_CFLAGS_32))
+KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic
+$(vdso32-images:%=$(obj)/%.dbg): KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)
+
 $(vdso32-images:%=$(obj)/%.dbg): $(obj)/vdso32-%.so.dbg: FORCE \
                                  $(obj)/vdso32/vdso32.lds \
+                                 $(obj)/vdso32/vclock_gettime.o \
                                  $(obj)/vdso32/note.o \
                                  $(obj)/vdso32/%.o
         $(call if_changed,vdso)
diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index 09dae4a1c6dc..90bb5e8027ac 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -4,6 +4,9 @@
  *
  * Fast user context implementation of clock_gettime, gettimeofday, and time.
  *
+ * 32 Bit compat layer by Stefani Seibold <stefani@seibold.net>
+ *  sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany
+ *
  * The code should have no internal unresolved relocations.
  * Check with readelf after changing.
  */
@@ -12,13 +15,11 @@
 #define DISABLE_BRANCH_PROFILING
 
 #include <linux/kernel.h>
-#include <linux/posix-timers.h>
-#include <linux/time.h>
+#include <uapi/linux/time.h>
 #include <linux/string.h>
 #include <asm/vsyscall.h>
 #include <asm/fixmap.h>
 #include <asm/vgtod.h>
-#include <asm/timex.h>
 #include <asm/hpet.h>
 #include <asm/unistd.h>
 #include <asm/io.h>
@@ -26,6 +27,12 @@
 
 #define gtod (&VVAR(vsyscall_gtod_data))
 
+extern int __vdso_clock_gettime(clockid_t clock, struct timespec *ts);
+extern int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz);
+extern time_t __vdso_time(time_t *t);
+
+#ifndef BUILD_VDSO32
+
 static notrace cycle_t vread_hpet(void)
 {
         return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + HPET_COUNTER);
@@ -118,6 +125,59 @@ static notrace cycle_t vread_pvclock(int *mode)
 }
 #endif
 
+#else
+
+extern u8 hpet_page
+        __attribute__((visibility("hidden")));
+
+#ifdef CONFIG_HPET_TIMER
+static notrace cycle_t vread_hpet(void)
+{
+        return readl((const void __iomem *)(&hpet_page + HPET_COUNTER));
+}
+#endif
+
+notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
+{
+        long ret;
+
+        asm(
+                "mov %%ebx, %%edx \n"
+                "mov %2, %%ebx \n"
+                "call VDSO32_vsyscall \n"
+                "mov %%edx, %%ebx \n"
+                : "=a" (ret)
+                : "0" (__NR_clock_gettime), "g" (clock), "c" (ts)
+                : "memory", "edx");
+        return ret;
+}
+
+notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz)
+{
+        long ret;
+
+        asm(
+                "mov %%ebx, %%edx \n"
+                "mov %2, %%ebx \n"
+                "call VDSO32_vsyscall \n"
+                "mov %%edx, %%ebx \n"
+                : "=a" (ret)
+                : "0" (__NR_gettimeofday), "g" (tv), "c" (tz)
+                : "memory", "edx");
+        return ret;
+}
+
+#ifdef CONFIG_PARAVIRT_CLOCK
+
+static notrace cycle_t vread_pvclock(int *mode)
+{
+        *mode = VCLOCK_NONE;
+        return 0;
+}
+#endif
+
+#endif
+
 notrace static cycle_t vread_tsc(void)
 {
         cycle_t ret;
@@ -131,7 +191,7 @@ notrace static cycle_t vread_tsc(void)
          * but no one has ever seen it happen.
          */
         rdtsc_barrier();
-        ret = (cycle_t)vget_cycles();
+        ret = (cycle_t)__native_read_tsc();
 
         last = gtod->clock.cycle_last;
 
@@ -152,12 +212,14 @@ notrace static cycle_t vread_tsc(void)
 
 notrace static inline u64 vgetsns(int *mode)
 {
-        long v;
+        u64 v;
         cycles_t cycles;
         if (gtod->clock.vclock_mode == VCLOCK_TSC)
                 cycles = vread_tsc();
+#ifdef CONFIG_HPET_TIMER
         else if (gtod->clock.vclock_mode == VCLOCK_HPET)
                 cycles = vread_hpet();
+#endif
 #ifdef CONFIG_PARAVIRT_CLOCK
         else if (gtod->clock.vclock_mode == VCLOCK_PVCLOCK)
                 cycles = vread_pvclock(mode);
@@ -189,7 +251,7 @@ notrace static int __always_inline do_realtime(struct timespec *ts)
         return mode;
 }
 
-notrace static int do_monotonic(struct timespec *ts)
+notrace static int __always_inline do_monotonic(struct timespec *ts)
 {
         unsigned long seq;
         u64 ns;
@@ -284,7 +346,7 @@ int gettimeofday(struct timeval *, struct timezone *)
  */
 notrace time_t __vdso_time(time_t *t)
 {
-        /* This is atomic on x86_64 so we don't need any locks. */
+        /* This is atomic on x86 so we don't need any locks. */
         time_t result = ACCESS_ONCE(gtod->wall_time_sec);
 
         if (t)
diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S
index 8c550c1976f3..c6d0e1bf27a4 100644
--- a/arch/x86/vdso/vdso-layout.lds.S
+++ b/arch/x86/vdso/vdso-layout.lds.S
@@ -6,6 +6,24 @@
 
 SECTIONS
 {
+#ifdef BUILD_VDSO32
+#include <asm/vdso32.h>
+
+        .hpet_sect : {
+                hpet_page = . - VDSO_OFFSET(VDSO_HPET_PAGE);
+        } :text :hpet_sect
+
+        .vvar_sect : {
+                vvar = . - VDSO_OFFSET(VDSO_VVAR_PAGE);
+
+        /* Place all vvars at the offsets in asm/vvar.h. */
+#define EMIT_VVAR(name, offset) vvar_ ## name = vvar + offset;
+#define __VVAR_KERNEL_LDS
+#include <asm/vvar.h>
+#undef __VVAR_KERNEL_LDS
+#undef EMIT_VVAR
+        } :text :vvar_sect
+#endif
         . = SIZEOF_HEADERS;
 
         .hash           : { *(.hash) }                  :text
@@ -61,4 +79,8 @@ PHDRS
         dynamic         PT_DYNAMIC      FLAGS(4);               /* PF_R */
         note            PT_NOTE         FLAGS(4);               /* PF_R */
         eh_frame_hdr    PT_GNU_EH_FRAME;
+#ifdef BUILD_VDSO32
+        vvar_sect       PT_NULL         FLAGS(4);               /* PF_R */
+        hpet_sect       PT_NULL         FLAGS(4);               /* PF_R */
+#endif
 }
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index e0fc767bcad3..e10abdf4cc10 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -25,6 +25,9 @@
 #include <asm/tlbflush.h>
 #include <asm/vdso.h>
 #include <asm/proto.h>
+#include <asm/fixmap.h>
+#include <asm/hpet.h>
+#include <asm/vvar.h>
 
 #ifdef CONFIG_COMPAT_VDSO
 #define VDSO_DEFAULT    0
@@ -141,6 +144,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
         struct mm_struct *mm = current->mm;
         unsigned long addr;
         int ret = 0;
+        struct vm_area_struct *vma;
 
 #ifdef CONFIG_X86_X32_ABI
         if (test_thread_flag(TIF_X32))
@@ -163,14 +167,49 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
         /*
          * MAYWRITE to allow gdb to COW and set breakpoints
          */
-        ret = install_special_mapping(mm, addr, PAGE_SIZE,
-                                      VM_READ|VM_EXEC|
-                                      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
-                                      vdso32_pages);
+        ret = install_special_mapping(mm,
+                        addr,
+                        VDSO_OFFSET(VDSO_PAGES - VDSO_PREV_PAGES),
+                        VM_READ|VM_EXEC|
+                        VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+                        vdso32_pages);
 
         if (ret)
                 goto up_fail;
 
+        vma = _install_special_mapping(mm,
+                        addr -  VDSO_OFFSET(VDSO_PREV_PAGES),
+                        VDSO_OFFSET(VDSO_PREV_PAGES),
+                        VM_READ,
+                        NULL);
+
+        if (IS_ERR(vma)) {
+                ret = PTR_ERR(vma);
+                goto up_fail;
+        }
+
+        ret = remap_pfn_range(vma,
+                addr - VDSO_OFFSET(VDSO_VVAR_PAGE),
+                __pa_symbol(&__vvar_page) >> PAGE_SHIFT,
+                PAGE_SIZE,
+                PAGE_READONLY);
+
+        if (ret)
+                goto up_fail;
+
+#ifdef CONFIG_HPET_TIMER
+        if (hpet_address) {
+                ret = io_remap_pfn_range(vma,
+                        addr - VDSO_OFFSET(VDSO_HPET_PAGE),
+                        hpet_address >> PAGE_SHIFT,
+                        PAGE_SIZE,
+                        pgprot_noncached(PAGE_READONLY));
+
+                if (ret)
+                        goto up_fail;
+        }
+#endif
+
         current_thread_info()->sysenter_return =
                 VDSO32_SYMBOL(addr, SYSENTER_RETURN);
 
diff --git a/arch/x86/vdso/vdso32/vclock_gettime.c b/arch/x86/vdso/vdso32/vclock_gettime.c
new file mode 100644
index 000000000000..ca65e4213d63
--- /dev/null
+++ b/arch/x86/vdso/vdso32/vclock_gettime.c
@@ -0,0 +1,9 @@
+#define BUILD_VDSO32
+
+#ifndef CONFIG_CC_OPTIMIZE_FOR_SIZE
+#undef CONFIG_OPTIMIZE_INLINING
+#endif
+
+#undef CONFIG_X86_PPRO_FENCE
+
+#include "../vclock_gettime.c"
diff --git a/arch/x86/vdso/vdso32/vdso32.lds.S b/arch/x86/vdso/vdso32/vdso32.lds.S
index 90e7aa90dbe4..28c460703bbc 100644
--- a/arch/x86/vdso/vdso32/vdso32.lds.S
+++ b/arch/x86/vdso/vdso32/vdso32.lds.S
@@ -8,6 +8,11 @@
  * values visible using the asm-x86/vdso.h macros from the kernel proper.
  */
 
+#include <asm/page.h>
+
+#define BUILD_VDSO32
+#define VDSO_PRELINK 0
+
 #include "../vdso-layout.lds.S"
 
 /* The ELF entry point can be used to set the AT_SYSINFO value.  */
@@ -23,6 +28,9 @@ VERSION
                 __kernel_vsyscall;
                 __kernel_sigreturn;
                 __kernel_rt_sigreturn;
+                __vdso_clock_gettime;
+                __vdso_gettimeofday;
+                __vdso_time;
         local: *;
         };
 }
@@ -33,3 +41,6 @@ VERSION
 VDSO32_vsyscall         = __kernel_vsyscall;
 VDSO32_sigreturn        = __kernel_sigreturn;
 VDSO32_rt_sigreturn     = __kernel_rt_sigreturn;
+VDSO32_clock_gettime    = clock_gettime;
+VDSO32_gettimeofday     = gettimeofday;
+VDSO32_time             = time;