fix TLS layout of TLS variant I when there is a gap above TP

In TLS variant I the TLS is above TP (or above a fixed offset from TP)
but on some targets there is a reserved gap above TP before TLS starts.

This matters for the local-exec tls access model when the offsets of
TLS variables from the TP are hard coded by the linker into the
executable, so the libc must compute these offsets the same way as the
linker.  The tls offset of the main module has to be

	alignup(GAP_ABOVE_TP, main_tls_align).

If there is no TLS in the main module then the gap can be ignored
since musl does not use it and the tls access models of shared
libraries are not affected.

The previous setup only worked if (tls_align & -GAP_ABOVE_TP) == 0
(i.e. TLS did not require large alignment) because the gap was
treated as a fixed offset from TP.  Now the TP points at the end
of the pthread struct (which is aligned) and there is a gap above
it (which may also need alignment).

The fix required changing TP_ADJ and __pthread_self on affected
targets (aarch64, arm and sh) and in the tlsdesc asm the offset to
access the dtv changed too.

diff --git a/arch/aarch64/pthread_arch.h b/arch/aarch64/pthread_arch.h
index b2e2d8f13a5025aaa7da02b0050543c7fab0303a..e8499d8e200b1b8371e698a0d2275970ab2bcf7c 100644 (file)
--- a/arch/aarch64/pthread_arch.h
+++ b/arch/aarch64/pthread_arch.h
@@ -2,10 +2,11 @@ static inline struct pthread *__pthread_self()
 {
        char *self;
        __asm__ __volatile__ ("mrs %0,tpidr_el0" : "=r"(self));
-       return (void*)(self + 16 - sizeof(struct pthread));
+       return (void*)(self - sizeof(struct pthread));
 }
 
 #define TLS_ABOVE_TP
-#define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) - 16)
+#define GAP_ABOVE_TP 16
+#define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread))
 
 #define MC_PC pc

diff --git a/arch/aarch64/reloc.h b/arch/aarch64/reloc.h
index 51b66e23850f8e8cd20baa6f7f3f3f2eaee6cb6d..40cf0b2891660dca6b6b51e03b096113941bd7cd 100644 (file)
--- a/arch/aarch64/reloc.h
+++ b/arch/aarch64/reloc.h
@@ -10,7 +10,7 @@
 
 #define NO_LEGACY_INITFINI
 
-#define TPOFF_K 16
+#define TPOFF_K 0
 
 #define REL_SYMBOLIC    R_AARCH64_ABS64
 #define REL_GOT         R_AARCH64_GLOB_DAT

diff --git a/arch/arm/pthread_arch.h b/arch/arm/pthread_arch.h
index 6657e198eed3edbf1cf99d10b6eb011774d2c279..8f2ae8f82efb9682887253169156a957d9708c9c 100644 (file)
--- a/arch/arm/pthread_arch.h
+++ b/arch/arm/pthread_arch.h
@@ -5,7 +5,7 @@ static inline pthread_t __pthread_self()
 {
        char *p;
        __asm__ __volatile__ ( "mrc p15,0,%0,c13,c0,3" : "=r"(p) );
-       return (void *)(p+8-sizeof(struct pthread));
+       return (void *)(p-sizeof(struct pthread));
 }
 
 #else
@@ -21,12 +21,13 @@ static inline pthread_t __pthread_self()
        extern uintptr_t __attribute__((__visibility__("hidden"))) __a_gettp_ptr;
        register uintptr_t p __asm__("r0");
        __asm__ __volatile__ ( BLX " %1" : "=r"(p) : "r"(__a_gettp_ptr) : "cc", "lr" );
-       return (void *)(p+8-sizeof(struct pthread));
+       return (void *)(p-sizeof(struct pthread));
 }
 
 #endif
 
 #define TLS_ABOVE_TP
-#define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) - 8)
+#define GAP_ABOVE_TP 8
+#define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread))
 
 #define MC_PC arm_pc

diff --git a/arch/arm/reloc.h b/arch/arm/reloc.h
index b175711d8b8edf9c6dec735a6fd56b3a6af28cbf..4b00bf645e8cf98d115fa24accaaa2fb69f20ff0 100644 (file)
--- a/arch/arm/reloc.h
+++ b/arch/arm/reloc.h
@@ -16,7 +16,7 @@
 
 #define NO_LEGACY_INITFINI
 
-#define TPOFF_K 8
+#define TPOFF_K 0
 
 #define REL_SYMBOLIC    R_ARM_ABS32
 #define REL_GOT         R_ARM_GLOB_DAT

diff --git a/arch/mips/pthread_arch.h b/arch/mips/pthread_arch.h
index e5812655df8684f7e44204bf0561c9c0dade0ceb..5fea15ad5f290a5dac80db84b1d555696da1f6ac 100644 (file)
--- a/arch/mips/pthread_arch.h
+++ b/arch/mips/pthread_arch.h
@@ -11,6 +11,7 @@ static inline struct pthread *__pthread_self()
 }
 
 #define TLS_ABOVE_TP
+#define GAP_ABOVE_TP 0
 #define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) + 0x7000)
 
 #define DTP_OFFSET 0x8000

diff --git a/arch/mips64/pthread_arch.h b/arch/mips64/pthread_arch.h
index e5812655df8684f7e44204bf0561c9c0dade0ceb..5fea15ad5f290a5dac80db84b1d555696da1f6ac 100644 (file)
--- a/arch/mips64/pthread_arch.h
+++ b/arch/mips64/pthread_arch.h
@@ -11,6 +11,7 @@ static inline struct pthread *__pthread_self()
 }
 
 #define TLS_ABOVE_TP
+#define GAP_ABOVE_TP 0
 #define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) + 0x7000)
 
 #define DTP_OFFSET 0x8000

diff --git a/arch/mipsn32/pthread_arch.h b/arch/mipsn32/pthread_arch.h
index e5812655df8684f7e44204bf0561c9c0dade0ceb..5fea15ad5f290a5dac80db84b1d555696da1f6ac 100644 (file)
--- a/arch/mipsn32/pthread_arch.h
+++ b/arch/mipsn32/pthread_arch.h
@@ -11,6 +11,7 @@ static inline struct pthread *__pthread_self()
 }
 
 #define TLS_ABOVE_TP
+#define GAP_ABOVE_TP 0
 #define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) + 0x7000)
 
 #define DTP_OFFSET 0x8000

diff --git a/arch/or1k/pthread_arch.h b/arch/or1k/pthread_arch.h
index 7decd769a8598ab35de5293ccc2bf58b51a3c414..521b9c53b9f831ba09bc3a704577df76c81ceca9 100644 (file)
--- a/arch/or1k/pthread_arch.h
+++ b/arch/or1k/pthread_arch.h
@@ -12,6 +12,7 @@ static inline struct pthread *__pthread_self()
 }
 
 #define TLS_ABOVE_TP
+#define GAP_ABOVE_TP 0
 #define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread))
 
 #define MC_PC regs.pc

diff --git a/arch/powerpc/pthread_arch.h b/arch/powerpc/pthread_arch.h
index 7c5c4fadb2116382e4a3a15a8e2a7adbaa95bb06..79e5a09f925b75cc797cf8619077d310f7bd0c65 100644 (file)
--- a/arch/powerpc/pthread_arch.h
+++ b/arch/powerpc/pthread_arch.h
@@ -11,6 +11,7 @@ static inline struct pthread *__pthread_self()
 }
                         
 #define TLS_ABOVE_TP
+#define GAP_ABOVE_TP 0
 #define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) + 0x7000)
 
 #define DTP_OFFSET 0x8000

diff --git a/arch/powerpc64/pthread_arch.h b/arch/powerpc64/pthread_arch.h
index 2f976fe24d8bce41b98430677c440841a3b542f4..37b75e291992ce7cd4c5eaac4a16393d2f192f01 100644 (file)
--- a/arch/powerpc64/pthread_arch.h
+++ b/arch/powerpc64/pthread_arch.h
@@ -6,6 +6,7 @@ static inline struct pthread *__pthread_self()
 }
 
 #define TLS_ABOVE_TP
+#define GAP_ABOVE_TP 0
 #define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) + 0x7000)
 
 #define DTP_OFFSET 0x8000

diff --git a/arch/sh/pthread_arch.h b/arch/sh/pthread_arch.h
index 2756e7ec1934069e70fb996a680467f904264b39..41fefacfcf0377c64d5fddfef84222b99faabff8 100644 (file)
--- a/arch/sh/pthread_arch.h
+++ b/arch/sh/pthread_arch.h
@@ -2,10 +2,11 @@ static inline struct pthread *__pthread_self()
 {
        char *self;
        __asm__ __volatile__ ("stc gbr,%0" : "=r" (self) );
-       return (struct pthread *) (self + 8 - sizeof(struct pthread));
+       return (struct pthread *) (self - sizeof(struct pthread));
 }
 
 #define TLS_ABOVE_TP
-#define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread) - 8)
+#define GAP_ABOVE_TP 8
+#define TP_ADJ(p) ((char *)(p) + sizeof(struct pthread))
 
 #define MC_PC sc_pc

diff --git a/arch/sh/reloc.h b/arch/sh/reloc.h
index 0238ce075ba4d98718847fa38229259869dfeff6..a1f16cb157dbf382e9e51bf3fda6f5f2b13ecde0 100644 (file)
--- a/arch/sh/reloc.h
+++ b/arch/sh/reloc.h
@@ -20,7 +20,7 @@
 
 #define LDSO_ARCH "sh" ENDIAN_SUFFIX FP_SUFFIX ABI_SUFFIX
 
-#define TPOFF_K 8
+#define TPOFF_K 0
 
 #define REL_SYMBOLIC    R_SH_DIR32
 #define REL_OFFSET      R_SH_REL32

diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index cea5f4521ec9255d257b0a346191c2095038d15a..c6216b7c703f1b61b436d90ac77b5ae5f3c457e8 100644 (file)
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -1594,8 +1594,9 @@ _Noreturn void __dls3(size_t *sp)
                libc.tls_head = tls_tail = &app.tls;
                app.tls_id = tls_cnt = 1;
 #ifdef TLS_ABOVE_TP
-               app.tls.offset = 0;
-               tls_offset = app.tls.size
+               app.tls.offset = GAP_ABOVE_TP;
+               app.tls.offset += -GAP_ABOVE_TP & (app.tls.align-1);
+               tls_offset = app.tls.offset + app.tls.size
                        + ( -((uintptr_t)app.tls.image + app.tls.size)
                        & (app.tls.align-1) );
 #else

diff --git a/src/env/__init_tls.c b/src/env/__init_tls.c
index 1c5d98a030dd968a881c2759a76ebc23f6ff6cab..31d324a8ace03166d2eb6b393886bd7ccaf06afe 100644 (file)
--- a/src/env/__init_tls.c
+++ b/src/env/__init_tls.c
@@ -104,13 +104,19 @@ static void static_init_tls(size_t *aux)
 
        main_tls.size += (-main_tls.size - (uintptr_t)main_tls.image)
                & (main_tls.align-1);
-       if (main_tls.align < MIN_TLS_ALIGN) main_tls.align = MIN_TLS_ALIGN;
-#ifndef TLS_ABOVE_TP
+#ifdef TLS_ABOVE_TP
+       main_tls.offset = GAP_ABOVE_TP;
+       main_tls.offset += -GAP_ABOVE_TP & (main_tls.align-1);
+#else
        main_tls.offset = main_tls.size;
 #endif
+       if (main_tls.align < MIN_TLS_ALIGN) main_tls.align = MIN_TLS_ALIGN;
 
        libc.tls_align = main_tls.align;
        libc.tls_size = 2*sizeof(void *) + sizeof(struct pthread)
+#ifdef TLS_ABOVE_TP
+               + main_tls.offset
+#endif
                + main_tls.size + main_tls.align
                + MIN_TLS_ALIGN-1 & -MIN_TLS_ALIGN;
 

diff --git a/src/ldso/aarch64/tlsdesc.s b/src/ldso/aarch64/tlsdesc.s
index 8ed5c267849149013a23ada67fc6387cb0f27bab..8e4004d73ac58960de2b67ede6190844412442be 100644 (file)
--- a/src/ldso/aarch64/tlsdesc.s
+++ b/src/ldso/aarch64/tlsdesc.s
@@ -14,7 +14,7 @@ __tlsdesc_static:
 // size_t __tlsdesc_dynamic(size_t *a)
 // {
 //     struct {size_t modidx,off;} *p = (void*)a[1];
-//     size_t *dtv = *(size_t**)(tp + 16 - 8);
+//     size_t *dtv = *(size_t**)(tp - 8);
 //     if (p->modidx <= dtv[0])
 //             return dtv[p->modidx] + p->off - tp;
 //     return __tls_get_new(p) - tp;
@@ -28,8 +28,7 @@ __tlsdesc_dynamic:
        mrs x1,tpidr_el0      // tp
        ldr x0,[x0,#8]        // p
        ldr x2,[x0]           // p->modidx
-       add x3,x1,#8
-       ldr x3,[x3]           // dtv
+       ldr x3,[x1,#-8]       // dtv
        ldr x4,[x3]           // dtv[0]
        cmp x2,x4
        b.hi 1f