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From 45116f342057b7facecd3d05c2091ce3a77eda59 Mon Sep 17 00:00:00 2001
From: Nelson Chu <nelson.chu@sifive.com>
Date: Mon, 29 Nov 2021 04:48:20 -0800
Subject: [PATCH] RISC-V: jal cannot refer to a default visibility symbol for
shared object.
This is the original binutils bugzilla report,
https://sourceware.org/bugzilla/show_bug.cgi?id=28509
And this is the first version of the proposed binutils patch,
https://sourceware.org/pipermail/binutils/2021-November/118398.html
After applying the binutils patch, I get the the unexpected error when
building libgcc,
/scratch/nelsonc/riscv-gnu-toolchain/riscv-gcc/libgcc/config/riscv/div.S:42:
/scratch/nelsonc/build-upstream/rv64gc-linux/build-install/riscv64-unknown-linux-gnu/bin/ld: relocation R_RISCV_JAL against `__udivdi3' which may bind externally can not be used when making a shared object; recompile with -fPIC
Therefore, this patch add an extra hidden alias symbol for __udivdi3, and
then use HIDDEN_JUMPTARGET to target a non-preemptible symbol instead.
The solution is similar to glibc as follows,
https://sourceware.org/git/?p=glibc.git;a=commit;h=68389203832ab39dd0dbaabbc4059e7fff51c29b
libgcc/ChangeLog:
* config/riscv/div.S: Add the hidden alias symbol for __udivdi3, and
then use HIDDEN_JUMPTARGET to target it since it is non-preemptible.
* config/riscv/riscv-asm.h: Added new macros HIDDEN_JUMPTARGET and
HIDDEN_DEF.
---
libgcc/config/riscv/div.S | 15 ++++++++-------
libgcc/config/riscv/riscv-asm.h | 6 ++++++
2 files changed, 14 insertions(+), 7 deletions(-)
diff --git a/libgcc/config/riscv/div.S b/libgcc/config/riscv/div.S
index c9bd7879c1..723c3b82e4 100644
--- a/libgcc/config/riscv/div.S
+++ b/libgcc/config/riscv/div.S
@@ -40,7 +40,7 @@ FUNC_BEGIN (__udivsi3)
sll a0, a0, 32
sll a1, a1, 32
move t0, ra
- jal __udivdi3
+ jal HIDDEN_JUMPTARGET(__udivdi3)
sext.w a0, a0
jr t0
FUNC_END (__udivsi3)
@@ -52,7 +52,7 @@ FUNC_BEGIN (__umodsi3)
srl a0, a0, 32
srl a1, a1, 32
move t0, ra
- jal __udivdi3
+ jal HIDDEN_JUMPTARGET(__udivdi3)
sext.w a0, a1
jr t0
FUNC_END (__umodsi3)
@@ -95,11 +95,12 @@ FUNC_BEGIN (__udivdi3)
.L5:
ret
FUNC_END (__udivdi3)
+HIDDEN_DEF (__udivdi3)
FUNC_BEGIN (__umoddi3)
/* Call __udivdi3(a0, a1), then return the remainder, which is in a1. */
move t0, ra
- jal __udivdi3
+ jal HIDDEN_JUMPTARGET(__udivdi3)
move a0, a1
jr t0
FUNC_END (__umoddi3)
@@ -111,12 +112,12 @@ FUNC_END (__umoddi3)
bgtz a1, .L12 /* Compute __udivdi3(-a0, a1), then negate the result. */
neg a1, a1
- j __udivdi3 /* Compute __udivdi3(-a0, -a1). */
+ j HIDDEN_JUMPTARGET(__udivdi3) /* Compute __udivdi3(-a0, -a1). */
.L11: /* Compute __udivdi3(a0, -a1), then negate the result. */
neg a1, a1
.L12:
move t0, ra
- jal __udivdi3
+ jal HIDDEN_JUMPTARGET(__udivdi3)
neg a0, a0
jr t0
FUNC_END (__divdi3)
@@ -126,7 +127,7 @@ FUNC_BEGIN (__moddi3)
bltz a1, .L31
bltz a0, .L32
.L30:
- jal __udivdi3 /* The dividend is not negative. */
+ jal HIDDEN_JUMPTARGET(__udivdi3) /* The dividend is not negative. */
move a0, a1
jr t0
.L31:
@@ -134,7 +135,7 @@ FUNC_BEGIN (__moddi3)
bgez a0, .L30
.L32:
neg a0, a0
- jal __udivdi3 /* The dividend is hella negative. */
+ jal HIDDEN_JUMPTARGET(__udivdi3) /* The dividend is hella negative. */
neg a0, a1
jr t0
FUNC_END (__moddi3)
diff --git a/libgcc/config/riscv/riscv-asm.h b/libgcc/config/riscv/riscv-asm.h
index 8550707a4a..96dd85b0df 100644
--- a/libgcc/config/riscv/riscv-asm.h
+++ b/libgcc/config/riscv/riscv-asm.h
@@ -33,3 +33,9 @@ X:
#define FUNC_ALIAS(X,Y) \
.globl X; \
X = Y
+
+#define CONCAT1(a, b) CONCAT2(a, b)
+#define CONCAT2(a, b) a ## b
+#define HIDDEN_JUMPTARGET(X) CONCAT1(__hidden_, X)
+#define HIDDEN_DEF(X) FUNC_ALIAS(HIDDEN_JUMPTARGET(X), X); \
+ .hidden HIDDEN_JUMPTARGET(X)
--
2.49.0
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