diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/vdso/Makefile | 40 | ||||
| -rw-r--r-- | arch/x86/vdso/vdso-fakesections.c | 32 | ||||
| -rw-r--r-- | arch/x86/vdso/vdso2c.c | 19 | ||||
| -rw-r--r-- | arch/x86/vdso/vdso2c.h | 23 |
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); |