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-rw-r--r--arch/x86/vdso/Makefile40
-rw-r--r--arch/x86/vdso/vdso-fakesections.c32
-rw-r--r--arch/x86/vdso/vdso2c.c19
-rw-r--r--arch/x86/vdso/vdso2c.h23
4 files changed, 87 insertions, 27 deletions
diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index 9769df094035..3c0809a0631f 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -9,18 +9,9 @@ VDSOX32-$(CONFIG_X86_X32_ABI) := y
VDSO32-$(CONFIG_X86_32) := y
VDSO32-$(CONFIG_COMPAT) := y
-vdso-install-$(VDSO64-y) += vdso.so
-vdso-install-$(VDSOX32-y) += vdsox32.so
-vdso-install-$(VDSO32-y) += $(vdso32-images)
-
-
# files to link into the vdso
-vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o
-
-vobjs-$(VDSOX32-y) += $(vobjx32s-compat)
-
-# Filter out x32 objects.
-vobj64s := $(filter-out $(vobjx32s-compat),$(vobjs-y))
+vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vdso-fakesections.o
+vobjs-nox32 := vdso-fakesections.o
# files to link into kernel
obj-y += vma.o
@@ -34,7 +25,7 @@ vdso_img-$(VDSO32-y) += 32-sysenter
obj-$(VDSO32-y) += vdso32-setup.o
-vobjs := $(foreach F,$(vobj64s),$(obj)/$F)
+vobjs := $(foreach F,$(vobjs-y),$(obj)/$F)
$(obj)/vdso.o: $(obj)/vdso.so
@@ -104,7 +95,13 @@ VDSO_LDFLAGS_vdsox32.lds = -Wl,-m,elf32_x86_64 \
-Wl,-z,max-page-size=4096 \
-Wl,-z,common-page-size=4096
-vobjx32s-y := $(vobj64s:.o=-x32.o)
+# 64-bit objects to re-brand as x32
+vobjs64-for-x32 := $(filter-out $(vobjs-nox32),$(vobjs-y))
+
+# x32-rebranded versions
+vobjx32s-y := $(vobjs64-for-x32:.o=-x32.o)
+
+# same thing, but in the output directory
vobjx32s := $(foreach F,$(vobjx32s-y),$(obj)/$F)
# Convert 64bit object file to x32 for x32 vDSO.
@@ -176,15 +173,20 @@ VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) \
GCOV_PROFILE := n
#
-# Install the unstripped copy of vdso*.so listed in $(vdso-install-y).
+# Install the unstripped copies of vdso*.so.
#
-quiet_cmd_vdso_install = INSTALL $@
- cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
-$(vdso-install-y): %.so: $(obj)/%.so.dbg FORCE
+quiet_cmd_vdso_install = INSTALL $(@:install_%=%)
+ cmd_vdso_install = cp $< $(MODLIB)/vdso/$(@:install_%=%)
+
+vdso_img_insttargets := $(vdso_img_sodbg:%.dbg=install_%)
+
+$(MODLIB)/vdso: FORCE
@mkdir -p $(MODLIB)/vdso
+
+$(vdso_img_insttargets): install_%: $(obj)/%.dbg $(MODLIB)/vdso FORCE
$(call cmd,vdso_install)
-PHONY += vdso_install $(vdso-install-y)
-vdso_install: $(vdso-install-y)
+PHONY += vdso_install $(vdso_img_insttargets)
+vdso_install: $(vdso_img_insttargets) FORCE
clean-files := vdso32-syscall* vdso32-sysenter* vdso32-int80*
diff --git a/arch/x86/vdso/vdso-fakesections.c b/arch/x86/vdso/vdso-fakesections.c
new file mode 100644
index 000000000000..cb8a8d72c24b
--- /dev/null
+++ b/arch/x86/vdso/vdso-fakesections.c
@@ -0,0 +1,32 @@
+/*
+ * Copyright 2014 Andy Lutomirski
+ * Subject to the GNU Public License, v.2
+ *
+ * Hack to keep broken Go programs working.
+ *
+ * The Go runtime had a couple of bugs: it would read the section table to try
+ * to figure out how many dynamic symbols there were (it shouldn't have looked
+ * at the section table at all) and, if there were no SHT_SYNDYM section table
+ * entry, it would use an uninitialized value for the number of symbols. As a
+ * workaround, we supply a minimal section table. vdso2c will adjust the
+ * in-memory image so that "vdso_fake_sections" becomes the section table.
+ *
+ * The bug was introduced by:
+ * https://code.google.com/p/go/source/detail?r=56ea40aac72b (2012-08-31)
+ * and is being addressed in the Go runtime in this issue:
+ * https://code.google.com/p/go/issues/detail?id=8197
+ */
+
+#ifndef __x86_64__
+#error This hack is specific to the 64-bit vDSO
+#endif
+
+#include <linux/elf.h>
+
+extern const __visible struct elf64_shdr vdso_fake_sections[];
+const __visible struct elf64_shdr vdso_fake_sections[] = {
+ {
+ .sh_type = SHT_DYNSYM,
+ .sh_entsize = sizeof(Elf64_Sym),
+ }
+};
diff --git a/arch/x86/vdso/vdso2c.c b/arch/x86/vdso/vdso2c.c
index 450ac6eaf613..7a6bf50f9165 100644
--- a/arch/x86/vdso/vdso2c.c
+++ b/arch/x86/vdso/vdso2c.c
@@ -54,7 +54,7 @@ static void fail(const char *format, ...)
}
/*
- * Evil macros to do a little-endian read.
+ * Evil macros for little-endian reads and writes
*/
#define GLE(x, bits, ifnot) \
__builtin_choose_expr( \
@@ -62,11 +62,24 @@ static void fail(const char *format, ...)
(__typeof__(*(x)))get_unaligned_le##bits(x), ifnot)
extern void bad_get_le(void);
-#define LAST_LE(x) \
+#define LAST_GLE(x) \
__builtin_choose_expr(sizeof(*(x)) == 1, *(x), bad_get_le())
#define GET_LE(x) \
- GLE(x, 64, GLE(x, 32, GLE(x, 16, LAST_LE(x))))
+ GLE(x, 64, GLE(x, 32, GLE(x, 16, LAST_GLE(x))))
+
+#define PLE(x, val, bits, ifnot) \
+ __builtin_choose_expr( \
+ (sizeof(*(x)) == bits/8), \
+ put_unaligned_le##bits((val), (x)), ifnot)
+
+extern void bad_put_le(void);
+#define LAST_PLE(x, val) \
+ __builtin_choose_expr(sizeof(*(x)) == 1, *(x) = (val), bad_put_le())
+
+#define PUT_LE(x, val) \
+ PLE(x, val, 64, PLE(x, val, 32, PLE(x, val, 16, LAST_PLE(x, val))))
+
#define NSYMS (sizeof(required_syms) / sizeof(required_syms[0]))
diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
index 8a074637a576..c6eefaf389b9 100644
--- a/arch/x86/vdso/vdso2c.h
+++ b/arch/x86/vdso/vdso2c.h
@@ -18,6 +18,8 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
const char *secstrings;
uint64_t syms[NSYMS] = {};
+ uint64_t fake_sections_value = 0, fake_sections_size = 0;
+
Elf_Phdr *pt = (Elf_Phdr *)(addr + GET_LE(&hdr->e_phoff));
/* Walk the segment table. */
@@ -84,6 +86,7 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
GET_LE(&symtab_hdr->sh_entsize) * i;
const char *name = addr + GET_LE(&strtab_hdr->sh_offset) +
GET_LE(&sym->st_name);
+
for (k = 0; k < NSYMS; k++) {
if (!strcmp(name, required_syms[k])) {
if (syms[k]) {
@@ -93,6 +96,13 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
syms[k] = GET_LE(&sym->st_value);
}
}
+
+ if (!strcmp(name, "vdso_fake_sections")) {
+ if (fake_sections_value)
+ fail("duplicate vdso_fake_sections\n");
+ fake_sections_value = GET_LE(&sym->st_value);
+ fake_sections_size = GET_LE(&sym->st_size);
+ }
}
/* Validate mapping addresses. */
@@ -112,11 +122,14 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
if (syms[sym_end_mapping] % 4096)
fail("end_mapping must be a multiple of 4096\n");
- /* Remove sections. */
- hdr->e_shoff = 0;
- hdr->e_shentsize = 0;
- hdr->e_shnum = 0;
- hdr->e_shstrndx = htole16(SHN_UNDEF);
+ /* Remove sections or use fakes */
+ if (fake_sections_size % sizeof(Elf_Shdr))
+ fail("vdso_fake_sections size is not a multiple of %ld\n",
+ (long)sizeof(Elf_Shdr));
+ PUT_LE(&hdr->e_shoff, fake_sections_value);
+ PUT_LE(&hdr->e_shentsize, fake_sections_value ? sizeof(Elf_Shdr) : 0);
+ PUT_LE(&hdr->e_shnum, fake_sections_size / sizeof(Elf_Shdr));
+ PUT_LE(&hdr->e_shstrndx, SHN_UNDEF);
if (!name) {
fwrite(addr, load_size, 1, outfile);
generated by cgit v1.2.3 (git 2.39.1) at 2024-10-30 15:17:19 +0000