summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorRich Felker <dalias@aerifal.cx>2018-10-01 18:37:02 -0400
committerRich Felker <dalias@aerifal.cx>2018-10-01 18:37:02 -0400
commit0beb9dfbecad38af9759b1e83eeb007e28b70abb (patch)
tree75c42c8b544a480ba0a7664ebe83d88de654cd60
parent4d0a82170a25464c39522d7190b9fe302045ddb2 (diff)
downloadmusl-0beb9dfbecad38af9759b1e83eeb007e28b70abb.tar.gz
add TLSDESC support for 32-bit arm
unlike other asm where the baseline ISA is used, these functions are hot paths and use ISA-level specializations. call-clobbered vfp registers are saved before calling __tls_get_new, since there is no guarantee it won't use them. while setjmp/longjmp have to use hwcap to decide whether to the fpu is in use, since application code could be using vfp registers even if libc was compiled as pure softfloat, __tls_get_new is part of libc and can be assumed not to have access to vfp registers if tlsdesc.S does not. thus it suffices just to check the predefined preprocessor macros. the check for __ARM_PCS_VFP is redundant; !__SOFTFP__ must always be true if the target ISA level includes fpu instructions/registers.
-rw-r--r--arch/arm/reloc.h4
-rw-r--r--ldso/dynlink.c7
-rw-r--r--src/ldso/arm/tlsdesc.S62
3 files changed, 72 insertions, 1 deletions
diff --git a/arch/arm/reloc.h b/arch/arm/reloc.h
index 4b00bf64..2c2e7f58 100644
--- a/arch/arm/reloc.h
+++ b/arch/arm/reloc.h
@@ -26,7 +26,9 @@
#define REL_DTPMOD R_ARM_TLS_DTPMOD32
#define REL_DTPOFF R_ARM_TLS_DTPOFF32
#define REL_TPOFF R_ARM_TLS_TPOFF32
-//#define REL_TLSDESC R_ARM_TLS_DESC
+#define REL_TLSDESC R_ARM_TLS_DESC
+
+#define TLSDESC_BACKWARDS
#define CRTJMP(pc,sp) __asm__ __volatile__( \
"mov sp,%1 ; bx %0" : : "r"(pc), "r"(sp) : "memory" )
diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index 3ecbddfa..c2892b90 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -458,6 +458,13 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
+ addend;
#endif
}
+#ifdef TLSDESC_BACKWARDS
+ /* Some archs (32-bit ARM at least) invert the order of
+ * the descriptor members. Fix them up here. */
+ size_t tmp = reloc_addr[0];
+ reloc_addr[0] = reloc_addr[1];
+ reloc_addr[1] = tmp;
+#endif
break;
default:
error("Error relocating %s: unsupported relocation type %d",
diff --git a/src/ldso/arm/tlsdesc.S b/src/ldso/arm/tlsdesc.S
new file mode 100644
index 00000000..f3d67fce
--- /dev/null
+++ b/src/ldso/arm/tlsdesc.S
@@ -0,0 +1,62 @@
+.syntax unified
+
+.text
+.global __tlsdesc_static
+.hidden __tlsdesc_static
+.type __tlsdesc_static,%function
+__tlsdesc_static:
+ ldr r0,[r0]
+ bx lr
+
+.hidden __tls_get_new
+
+.global __tlsdesc_dynamic
+.hidden __tlsdesc_dynamic
+.type __tlsdesc_dynamic,%function
+__tlsdesc_dynamic:
+ push {r2,r3,ip,lr}
+ ldr r1,[r0]
+ ldr r2,[r1,#4] // r2 = offset
+ ldr r1,[r1] // r1 = modid
+
+ ldr r0,1f
+ add r0,r0,pc
+ ldr r0,[r0]
+2:
+#if __ARM_ARCH >= 5
+ blx r0 // r0 = tp
+#else
+ mov lr,pc
+ bx r0
+#endif
+ ldr r3,[r0,#-4] // r3 = dtv
+ ldr ip,[r3] // ip = dtv slot count
+ cmp r1,ip
+ bhi 3f
+ ldr ip,[r3,r1,LSL #2]
+ sub r0,ip,r0
+ add r0,r0,r2 // r0 = r3[r1]-r0+r2
+4:
+#if __ARM_ARCH >= 5
+ pop {r2,r3,ip,pc}
+#else
+ pop {r2,r3,ip,lr}
+ bx lr
+#endif
+
+3:
+#if __ARM_PCS_VFP || !__SOFTFP__
+ vpush {d0-d7}
+#endif
+ push {r0-r3}
+ add r0,sp,#4
+ bl __tls_get_new
+ pop {r1-r3,ip}
+#if __ARM_PCS_VFP || !__SOFTFP__
+ vpop {d0-d7}
+#endif
+ sub r0,r0,r1 // r0 = retval-tp
+ b 4b
+
+ .align 2
+1: .word __a_gettp_ptr - 2b