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| 1 | +From 45116f342057b7facecd3d05c2091ce3a77eda59 Mon Sep 17 00:00:00 2001 |
| 2 | +From: Nelson Chu < [email protected]> |
| 3 | +Date: Mon, 29 Nov 2021 04:48:20 -0800 |
| 4 | +Subject: [PATCH] RISC-V: jal cannot refer to a default visibility symbol for |
| 5 | + shared object. |
| 6 | + |
| 7 | +This is the original binutils bugzilla report, |
| 8 | +https://sourceware.org/bugzilla/show_bug.cgi?id=28509 |
| 9 | + |
| 10 | +And this is the first version of the proposed binutils patch, |
| 11 | +https://sourceware.org/pipermail/binutils/2021-November/118398.html |
| 12 | + |
| 13 | +After applying the binutils patch, I get the the unexpected error when |
| 14 | +building libgcc, |
| 15 | + |
| 16 | +/scratch/nelsonc/riscv-gnu-toolchain/riscv-gcc/libgcc/config/riscv/div.S:42: |
| 17 | +/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 |
| 18 | + |
| 19 | +Therefore, this patch add an extra hidden alias symbol for __udivdi3, and |
| 20 | +then use HIDDEN_JUMPTARGET to target a non-preemptible symbol instead. |
| 21 | +The solution is similar to glibc as follows, |
| 22 | +https://sourceware.org/git/?p=glibc.git;a=commit;h=68389203832ab39dd0dbaabbc4059e7fff51c29b |
| 23 | + |
| 24 | +libgcc/ChangeLog: |
| 25 | + |
| 26 | + * config/riscv/div.S: Add the hidden alias symbol for __udivdi3, and |
| 27 | + then use HIDDEN_JUMPTARGET to target it since it is non-preemptible. |
| 28 | + * config/riscv/riscv-asm.h: Added new macros HIDDEN_JUMPTARGET and |
| 29 | + HIDDEN_DEF. |
| 30 | +--- |
| 31 | + libgcc/config/riscv/div.S | 15 ++++++++------- |
| 32 | + libgcc/config/riscv/riscv-asm.h | 6 ++++++ |
| 33 | + 2 files changed, 14 insertions(+), 7 deletions(-) |
| 34 | + |
| 35 | +diff --git a/libgcc/config/riscv/div.S b/libgcc/config/riscv/div.S |
| 36 | +index c9bd7879c1e36..723c3b82e48c6 100644 |
| 37 | +--- a/libgcc/config/riscv/div.S |
| 38 | ++++ b/libgcc/config/riscv/div.S |
| 39 | +@@ -40,7 +40,7 @@ FUNC_BEGIN (__udivsi3) |
| 40 | + sll a0, a0, 32 |
| 41 | + sll a1, a1, 32 |
| 42 | + move t0, ra |
| 43 | +- jal __udivdi3 |
| 44 | ++ jal HIDDEN_JUMPTARGET(__udivdi3) |
| 45 | + sext.w a0, a0 |
| 46 | + jr t0 |
| 47 | + FUNC_END (__udivsi3) |
| 48 | +@@ -52,7 +52,7 @@ FUNC_BEGIN (__umodsi3) |
| 49 | + srl a0, a0, 32 |
| 50 | + srl a1, a1, 32 |
| 51 | + move t0, ra |
| 52 | +- jal __udivdi3 |
| 53 | ++ jal HIDDEN_JUMPTARGET(__udivdi3) |
| 54 | + sext.w a0, a1 |
| 55 | + jr t0 |
| 56 | + FUNC_END (__umodsi3) |
| 57 | +@@ -95,11 +95,12 @@ FUNC_BEGIN (__udivdi3) |
| 58 | + .L5: |
| 59 | + ret |
| 60 | + FUNC_END (__udivdi3) |
| 61 | ++HIDDEN_DEF (__udivdi3) |
| 62 | + |
| 63 | + FUNC_BEGIN (__umoddi3) |
| 64 | + /* Call __udivdi3(a0, a1), then return the remainder, which is in a1. */ |
| 65 | + move t0, ra |
| 66 | +- jal __udivdi3 |
| 67 | ++ jal HIDDEN_JUMPTARGET(__udivdi3) |
| 68 | + move a0, a1 |
| 69 | + jr t0 |
| 70 | + FUNC_END (__umoddi3) |
| 71 | +@@ -111,12 +112,12 @@ FUNC_END (__umoddi3) |
| 72 | + bgtz a1, .L12 /* Compute __udivdi3(-a0, a1), then negate the result. */ |
| 73 | + |
| 74 | + neg a1, a1 |
| 75 | +- j __udivdi3 /* Compute __udivdi3(-a0, -a1). */ |
| 76 | ++ j HIDDEN_JUMPTARGET(__udivdi3) /* Compute __udivdi3(-a0, -a1). */ |
| 77 | + .L11: /* Compute __udivdi3(a0, -a1), then negate the result. */ |
| 78 | + neg a1, a1 |
| 79 | + .L12: |
| 80 | + move t0, ra |
| 81 | +- jal __udivdi3 |
| 82 | ++ jal HIDDEN_JUMPTARGET(__udivdi3) |
| 83 | + neg a0, a0 |
| 84 | + jr t0 |
| 85 | + FUNC_END (__divdi3) |
| 86 | +@@ -126,7 +127,7 @@ FUNC_BEGIN (__moddi3) |
| 87 | + bltz a1, .L31 |
| 88 | + bltz a0, .L32 |
| 89 | + .L30: |
| 90 | +- jal __udivdi3 /* The dividend is not negative. */ |
| 91 | ++ jal HIDDEN_JUMPTARGET(__udivdi3) /* The dividend is not negative. */ |
| 92 | + move a0, a1 |
| 93 | + jr t0 |
| 94 | + .L31: |
| 95 | +@@ -134,7 +135,7 @@ FUNC_BEGIN (__moddi3) |
| 96 | + bgez a0, .L30 |
| 97 | + .L32: |
| 98 | + neg a0, a0 |
| 99 | +- jal __udivdi3 /* The dividend is hella negative. */ |
| 100 | ++ jal HIDDEN_JUMPTARGET(__udivdi3) /* The dividend is hella negative. */ |
| 101 | + neg a0, a1 |
| 102 | + jr t0 |
| 103 | + FUNC_END (__moddi3) |
| 104 | +diff --git a/libgcc/config/riscv/riscv-asm.h b/libgcc/config/riscv/riscv-asm.h |
| 105 | +index 8550707a4a26a..96dd85b0df2e5 100644 |
| 106 | +--- a/libgcc/config/riscv/riscv-asm.h |
| 107 | ++++ b/libgcc/config/riscv/riscv-asm.h |
| 108 | +@@ -33,3 +33,9 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| 109 | + #define FUNC_ALIAS(X,Y) \ |
| 110 | + .globl X; \ |
| 111 | + X = Y |
| 112 | ++ |
| 113 | ++#define CONCAT1(a, b) CONCAT2(a, b) |
| 114 | ++#define CONCAT2(a, b) a ## b |
| 115 | ++#define HIDDEN_JUMPTARGET(X) CONCAT1(__hidden_, X) |
| 116 | ++#define HIDDEN_DEF(X) FUNC_ALIAS(HIDDEN_JUMPTARGET(X), X); \ |
| 117 | ++ .hidden HIDDEN_JUMPTARGET(X) |
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