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Subject[PATCH v17 08/10] Add 32 bit VDSO time support for 32 bit kernel
Date
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.

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
arch/x86/include/asm/vdso.h | 3 ++
arch/x86/include/asm/vdso32.h | 11 ++++++
arch/x86/vdso/Makefile | 7 ++++
arch/x86/vdso/vclock_gettime.c | 66 +++++++++++++++++++++++++++++++++--
arch/x86/vdso/vdso-layout.lds.S | 22 ++++++++++++
arch/x86/vdso/vdso32-setup.c | 53 ++++++++++++++++++++++++----
arch/x86/vdso/vdso32/vclock_gettime.c | 36 +++++++++++++++++++
arch/x86/vdso/vdso32/vdso32.lds.S | 9 +++++
8 files changed, 198 insertions(+), 9 deletions(-)
create mode 100644 arch/x86/include/asm/vdso32.h
create mode 100644 arch/x86/vdso/vdso32/vclock_gettime.c

diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index fddb53d..fe3cef9 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -2,6 +2,9 @@
#define _ASM_X86_VDSO_H

#if defined CONFIG_X86_32 || defined CONFIG_COMPAT
+
+#include <asm/vdso32.h>
+
extern const char VDSO32_PRELINK[];

/*
diff --git a/arch/x86/include/asm/vdso32.h b/arch/x86/include/asm/vdso32.h
new file mode 100644
index 0000000..7efb701
--- /dev/null
+++ b/arch/x86/include/asm/vdso32.h
@@ -0,0 +1,11 @@
+#ifndef _ASM_X86_VDSO32_H
+#define _ASM_X86_VDSO32_H
+
+#define VDSO_BASE_PAGE 0
+#define VDSO_VVAR_PAGE 1
+#define VDSO_HPET_PAGE 2
+#define VDSO_PAGES 3
+#define VDSO_PREV_PAGES 2
+#define VDSO_OFFSET(x) ((x) * PAGE_SIZE)
+
+#endif
diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index fd14be1..1ff5b0a 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -145,8 +145,15 @@ 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 += -m32 -msoft-float -mregparm=3 -freg-struct-return -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 09dae4a..4f8c34a 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.
*/
@@ -26,6 +29,8 @@

#define gtod (&VVAR(vsyscall_gtod_data))

+#ifndef BUILD_VDSO32
+
static notrace cycle_t vread_hpet(void)
{
return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + HPET_COUNTER);
@@ -118,6 +123,59 @@ static notrace cycle_t vread_pvclock(int *mode)
}
#endif

+#else
+
+u8 hpet_page
+ __attribute__((visibility("hidden")));
+
+#ifdef CONFIG_HPET_TIMER
+static notrace cycle_t vread_hpet(void)
+{
+ return readl(&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 +189,7 @@ 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 +210,14 @@ 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);
@@ -284,7 +344,7 @@ 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 634a2cf..1261437 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
. = VDSO_PRELINK + 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 d6bfb87..9b57770 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>

enum {
VDSO_DISABLED = 0,
@@ -193,7 +196,7 @@ static __init void relocate_vdso(Elf32_Ehdr *ehdr)
}
}

-static struct page *vdso32_pages[1];
+static struct page *vdso32_pages[VDSO_PAGES];

#ifdef CONFIG_X86_64

@@ -310,6 +313,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
unsigned long addr;
int ret = 0;
bool compat;
+ struct vm_area_struct *vma;

#ifdef CONFIG_X86_X32_ABI
if (test_thread_flag(TIF_X32))
@@ -330,11 +334,13 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
if (compat)
addr = VDSO_HIGH_BASE;
else {
- addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
+ addr = get_unmapped_area(NULL, 0, VDSO_OFFSET(VDSO_PAGES), 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
}
+
+ addr += VDSO_OFFSET(VDSO_PREV_PAGES);
}

current->mm->context.vdso = (void *)addr;
@@ -343,13 +349,48 @@ 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 =
diff --git a/arch/x86/vdso/vdso32/vclock_gettime.c b/arch/x86/vdso/vdso32/vclock_gettime.c
new file mode 100644
index 0000000..ffdbdb1
--- /dev/null
+++ b/arch/x86/vdso/vdso32/vclock_gettime.c
@@ -0,0 +1,36 @@
+#define BUILD_VDSO32
+
+#ifdef CONFIG_X86_64
+
+/*
+ * Due the -m32 compilation, there will be a lot of
+ * "warning: integer constant is too large for 'unsigned long' type",
+ * because an unsigned long is only 32 bit.
+ */
+
+/*
+ * Prevents the include of arch/x86/include/asm/page.h, which will generate
+ * a lot of warnings.
+ */
+#define _ASM_X86_PAGE_H
+
+/*
+ * The unneeded inline function phys_to_virt() in arch/x86/include/asm/io.h
+ * depends on the __va(), which comes from arch/x86/include/asm/page.h.
+ * So add a dummy for this.
+ *
+ * It is save, since this functions not used in arch/x86/vdso/vclock_gettime.c
+ */
+#define __va(x) 0
+
+/*
+ * The define of CONFIG_ILLEGAL_POINTER_VALUE is also to prevent the
+ * "warning: integer constant is too large..."
+ */
+#undef CONFIG_ILLEGAL_POINTER_VALUE
+#define CONFIG_ILLEGAL_POINTER_VALUE 0
+
+#endif
+
+#include "../vclock_gettime.c"
+
diff --git a/arch/x86/vdso/vdso32/vdso32.lds.S b/arch/x86/vdso/vdso32/vdso32.lds.S
index 976124b..bc8bf6d 100644
--- a/arch/x86/vdso/vdso32/vdso32.lds.S
+++ b/arch/x86/vdso/vdso32/vdso32.lds.S
@@ -8,6 +8,9 @@
* 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"

@@ -24,6 +27,9 @@ VERSION
__kernel_vsyscall;
__kernel_sigreturn;
__kernel_rt_sigreturn;
+ __vdso_clock_gettime;
+ __vdso_gettimeofday;
+ __vdso_time;
local: *;
};
}
@@ -35,3 +41,6 @@ VDSO32_PRELINK = VDSO_PRELINK;
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;
--
1.8.5.4


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