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Merge "Revert "[MIPS] Support FR=0 emulation on FR=1 64-bit FP registers""

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This commit is contained in:
Dimitry Ivanov 2015-06-24 20:44:36 +00:00 committed by Gerrit Code Review
commit c666838ad6
3 changed files with 6 additions and 153 deletions
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6
linker/linker.cpp
View file

@ -2875,12 +2875,6 @@ bool soinfo::prelink_image() {
}
}
#if defined(__mips__) && !defined(__LP64__)
if (!mips_check_and_adjust_fp_modes()) {
return false;
}
#endif
DEBUG("si->base = %p, si->strtab = %p, si->symtab = %p",
reinterpret_cast<void*>(base), strtab_, symtab_);

4
linker/linker.h
View file

@ -250,9 +250,7 @@ struct soinfo {
bool mips_relocate_got(const VersionTracker& version_tracker,
const soinfo_list_t& global_group,
const soinfo_list_t& local_group);
#if !defined(__LP64__)
bool mips_check_and_adjust_fp_modes();
#endif
#endif
size_t ref_count_;
public:

149
linker/linker_mips.cpp
View file

@ -26,21 +26,8 @@
* SUCH DAMAGE.
*/
#if !defined(__LP64__) && __mips_isa_rev >= 5
#include <sys/prctl.h>
#if defined(PR_SET_FP_MODE)
#error "remove following defs when avail in Android's kernel headers"
#else
#define PR_SET_FP_MODE 45
#define PR_GET_FP_MODE 46
#define PR_FP_MODE_FR (1 << 0)
#define PR_FP_MODE_FRE (1 << 1)
#endif
#endif
#include "linker.h"
#include "linker_debug.h"
#include "linker_phdr.h"
#include "linker_relocs.h"
#include "linker_reloc_iterators.h"
#include "linker_sleb128.h"
@ -75,7 +62,7 @@ bool soinfo::relocate(const VersionTracker& version_tracker,
ElfW(Addr) sym_addr = 0;
const char* sym_name = nullptr;
DEBUG("Processing '%s' relocation at index %zd", get_realpath(), idx);
DEBUG("Processing '%s' relocation at index %zd", get_soname(), idx);
if (type == R_GENERIC_NONE) {
continue;
}
@ -97,8 +84,7 @@ bool soinfo::relocate(const VersionTracker& version_tracker,
if (s == nullptr) {
// mips does not support relocation with weak-undefined symbols
DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...",
sym_name, get_realpath());
DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, get_soname());
return false;
} else {
// We got a definition.
@ -185,22 +171,20 @@ bool soinfo::mips_relocate_got(const VersionTracker& version_tracker,
}
} else if (st_visibility == STV_PROTECTED) {
if (local_sym->st_value == 0) {
DL_ERR("%s: invalid symbol \"%s\" (PROTECTED/UNDEFINED) ",
get_realpath(), sym_name);
DL_ERR("%s: invalid symbol \"%s\" (PROTECTED/UNDEFINED) ", get_soname(), sym_name);
return false;
}
s = local_sym;
lsi = this;
} else {
DL_ERR("%s: invalid symbol \"%s\" visibility: 0x%x",
get_realpath(), sym_name, st_visibility);
DL_ERR("%s: invalid symbol \"%s\" visibility: 0x%x", get_soname(), sym_name, st_visibility);
return false;
}
if (s == nullptr) {
// We only allow an undefined symbol if this is a weak reference.
if (ELF_ST_BIND(local_sym->st_info) != STB_WEAK) {
DL_ERR("%s: cannot locate \"%s\"...", get_realpath(), sym_name);
DL_ERR("%s: cannot locate \"%s\"...", get_soname(), sym_name);
return false;
}
*got = 0;
@ -214,126 +198,3 @@ bool soinfo::mips_relocate_got(const VersionTracker& version_tracker,
return true;
}
#if !defined(__LP64__)
// Checks for mips32's various floating point abis.
// (Mips64 Android has a single floating point abi and doesn't need any checks)
// Linux kernel has declarations similar to the following
// in <linux>/arch/mips/include/asm/elf.h,
// but that non-uapi internal header file will never be imported
// into bionic's kernel headers.
#define PT_MIPS_ABIFLAGS 0x70000003 // is .MIPS.abiflags segment
struct mips_elf_abiflags_v0 {
uint16_t version; // version of this structure
uint8_t isa_level, isa_rev, gpr_size, cpr1_size, cpr2_size;
uint8_t fp_abi; // mips32 ABI variants for floating point
uint16_t isa_ext, ases, flags1, flags2;
};
// Bits of flags1:
#define MIPS_AFL_FLAGS1_ODDSPREG 1 // Uses odd-numbered single-prec fp regs
// Some values of fp_abi: via compiler flag:
#define MIPS_ABI_FP_DOUBLE 1 // -mdouble-float
#define MIPS_ABI_FP_XX 5 // -mfpxx
#define MIPS_ABI_FP_64A 7 // -mips32r* -mfp64 -mno-odd-spreg
#if __mips_isa_rev >= 5
static bool mips_fre_mode_on = false; // have set FRE=1 mode for process
#endif
bool soinfo::mips_check_and_adjust_fp_modes() {
mips_elf_abiflags_v0* abiflags = nullptr;
int mips_fpabi;
// Find soinfo's optional .MIPS.abiflags segment
for (size_t i = 0; i<phnum; ++i) {
const ElfW(Phdr)& ph = phdr[i];
if (ph.p_type == PT_MIPS_ABIFLAGS) {
if (ph.p_filesz < sizeof (mips_elf_abiflags_v0)) {
DL_ERR("Corrupt PT_MIPS_ABIFLAGS header found \"%s\"", get_realpath());
return false;
}
abiflags = reinterpret_cast<mips_elf_abiflags_v0*>(ph.p_vaddr + load_bias);
break;
}
}
// FP ABI-variant compatibility checks for MIPS o32 ABI
if (abiflags == nullptr) {
// Old compiles lack the new abiflags section.
// These compilers used -mfp32 -mdouble-float -modd-spreg defaults,
// ie FP32 aka DOUBLE, using odd-numbered single-prec regs
mips_fpabi = MIPS_ABI_FP_DOUBLE;
} else {
mips_fpabi = abiflags->fp_abi;
if ( (abiflags->flags1 & MIPS_AFL_FLAGS1_ODDSPREG)
&& (mips_fpabi == MIPS_ABI_FP_XX ||
mips_fpabi == MIPS_ABI_FP_64A ) ) {
// Android supports fewer cases than Linux
DL_ERR("Unsupported odd-single-prec FloatPt reg uses in \"%s\"",
get_realpath());
return false;
}
}
if (!(mips_fpabi == MIPS_ABI_FP_DOUBLE ||
#if __mips_isa_rev >= 5
mips_fpabi == MIPS_ABI_FP_64A ||
#endif
mips_fpabi == MIPS_ABI_FP_XX )) {
DL_ERR("Unsupported MIPS32 FloatPt ABI %d found in \"%s\"",
mips_fpabi, get_realpath());
return false;
}
#if __mips_isa_rev >= 5
// Adjust process's FR Emulation mode, if needed
//
// On Mips R5 & R6, Android runs continuously in FR=1 64bit-fpreg mode.
// NDK mips32 apps compiled with old compilers generate FP32 code
// which expects FR=0 32-bit fp registers.
// NDK mips32 apps compiled with newer compilers generate modeless
// FPXX code which runs on both FR=0 and FR=1 modes.
// Android itself is compiled in FP64A which requires FR=1 mode.
// FP32, FPXX, and FP64A all interlink okay, without dynamic FR mode
// changes during calls. For details, see
// http://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking
// Processes containing FR32 FR=0 code are run via kernel software assist,
// which maps all odd-numbered single-precision reg refs onto the
// upper half of the paired even-numbered double-precision reg.
// FRE=1 triggers traps to the kernel's emulator on every single-precision
// fp op (for both odd and even-numbered registers).
// Turning on FRE=1 traps is done at most once per process, simultanously
// for all threads of that process, when dlopen discovers FP32 code.
// The kernel repacks threads' registers when FRE mode is turn on or off.
// These asynchronous adjustments are wrong if any thread was executing
// FPXX code using odd-numbered single-precision regs.
// Current Android compilers default to the -mno-oddspreg option,
// and this requirement is checked by Android's dlopen.
// So FRE can always be safely turned on for FP32, anytime.
// Deferred enhancement: Allow loading of odd-spreg FPXX modules.
if (mips_fpabi == MIPS_ABI_FP_DOUBLE && !mips_fre_mode_on) {
// Turn on FRE mode, which emulates mode-sensitive FR=0 code on FR=1
// register files, by trapping to kernel on refs to single-precision regs
if (prctl(PR_SET_FP_MODE, PR_FP_MODE_FR|PR_FP_MODE_FRE)) {
DL_ERR("Kernel or cpu failed to set FRE mode required for running \"%s\"",
get_realpath());
return false;
}
DL_WARN("Using FRE=1 mode to run \"%s\"", get_realpath());
mips_fre_mode_on = true; // Avoid future redundant mode-switch calls
// FRE mode is never turned back off.
// Deferred enhancement:
// Reset FRE mode when dlclose() removes all FP32 modules
}
#else
// Android runs continuously in FR=0 32bit-fpreg mode.
#endif // __mips_isa_rev
return true;
}
#endif // __LP64___