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commit 387bff63dc2dccd62b09aa26dccf8cdc5f3c985c
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Author: Matheus Castanho <msc@linux.ibm.com>
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Date:   Tue Oct 26 10:44:59 2021 -0300
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    powerpc64[le]: Fix CFI and LR save address for asm syscalls [BZ #28532]
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    Syscalls based on the assembly templates are missing CFI for r31, which gets
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    clobbered when scv is used, and info for LR is inaccurate, placed in the wrong
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    LOC and not using the proper offset. LR was also being saved to the callee's
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    frame, while the ABI mandates it to be saved to the caller's frame. These are
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    fixed by this commit.
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    After this change:
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    $ readelf -wF libc.so.6 | grep 0004b9d4.. -A 7 && objdump --disassemble=kill libc.so.6
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    00004a48 0000000000000020 00004a4c FDE cie=00000000 pc=000000000004b9d4..000000000004ba3c
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       LOC           CFA      r31   ra
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    000000000004b9d4 r1+0     u     u
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    000000000004b9e4 r1+48    u     u
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    000000000004b9e8 r1+48    c-16  u
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    000000000004b9fc r1+48    c-16  c+16
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    000000000004ba08 r1+48    c-16
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    000000000004ba18 r1+48    u
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    000000000004ba1c r1+0     u
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    libc.so.6:     file format elf64-powerpcle
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    Disassembly of section .text:
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    000000000004b9d4 <kill>:
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       4b9d4:       1f 00 4c 3c     addis   r2,r12,31
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       4b9d8:       2c c3 42 38     addi    r2,r2,-15572
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       4b9dc:       25 00 00 38     li      r0,37
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       4b9e0:       d1 ff 21 f8     stdu    r1,-48(r1)
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       4b9e4:       20 00 e1 fb     std     r31,32(r1)
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       4b9e8:       98 8f ed eb     ld      r31,-28776(r13)
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       4b9ec:       10 00 ff 77     andis.  r31,r31,16
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       4b9f0:       1c 00 82 41     beq     4ba0c <kill+0x38>
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       4b9f4:       a6 02 28 7d     mflr    r9
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       4b9f8:       40 00 21 f9     std     r9,64(r1)
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       4b9fc:       01 00 00 44     scv     0
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       4ba00:       40 00 21 e9     ld      r9,64(r1)
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       4ba04:       a6 03 28 7d     mtlr    r9
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       4ba08:       08 00 00 48     b       4ba10 <kill+0x3c>
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       4ba0c:       02 00 00 44     sc
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       4ba10:       00 00 bf 2e     cmpdi   cr5,r31,0
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       4ba14:       20 00 e1 eb     ld      r31,32(r1)
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       4ba18:       30 00 21 38     addi    r1,r1,48
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       4ba1c:       18 00 96 41     beq     cr5,4ba34 <kill+0x60>
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       4ba20:       01 f0 20 39     li      r9,-4095
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       4ba24:       40 48 23 7c     cmpld   r3,r9
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       4ba28:       20 00 e0 4d     bltlr+
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       4ba2c:       d0 00 63 7c     neg     r3,r3
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       4ba30:       08 00 00 48     b       4ba38 <kill+0x64>
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       4ba34:       20 00 e3 4c     bnslr+
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       4ba38:       c8 32 fe 4b     b       2ed00 <__syscall_error>
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            ...
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       4ba44:       40 20 0c 00     .long 0xc2040
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       4ba48:       68 00 00 00     .long 0x68
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       4ba4c:       06 00 5f 5f     rlwnm   r31,r26,r0,0,3
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       4ba50:       6b 69 6c 6c     xoris   r12,r3,26987
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    (cherry picked from commit d120fb9941be1fb1934f0b50c6ad64e4c5e404fb)
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diff --git a/sysdeps/powerpc/powerpc64/sysdep.h b/sysdeps/powerpc/powerpc64/sysdep.h
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index 589f7c8d18814ee9..cfcfa69f91f1773d 100644
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--- a/sysdeps/powerpc/powerpc64/sysdep.h
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+++ b/sysdeps/powerpc/powerpc64/sysdep.h
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@@ -275,12 +275,14 @@ LT_LABELSUFFIX(name,_name_end): ; \
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 /* Allocate frame and save register */
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 #define NVOLREG_SAVE \
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     stdu r1,-SCV_FRAME_SIZE(r1); \
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+    cfi_adjust_cfa_offset(SCV_FRAME_SIZE); \
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     std r31,SCV_FRAME_NVOLREG_SAVE(r1); \
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-    cfi_adjust_cfa_offset(SCV_FRAME_SIZE);
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+    cfi_rel_offset(r31,SCV_FRAME_NVOLREG_SAVE);
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 /* Restore register and destroy frame */
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 #define NVOLREG_RESTORE	\
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     ld r31,SCV_FRAME_NVOLREG_SAVE(r1); \
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+    cfi_restore(r31); \
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     addi r1,r1,SCV_FRAME_SIZE; \
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     cfi_adjust_cfa_offset(-SCV_FRAME_SIZE);
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@@ -331,13 +333,13 @@ LT_LABELSUFFIX(name,_name_end): ; \
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 #define DO_CALL_SCV \
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     mflr r9; \
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-    std r9,FRAME_LR_SAVE(r1); \
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-    cfi_offset(lr,FRAME_LR_SAVE); \
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+    std r9,SCV_FRAME_SIZE+FRAME_LR_SAVE(r1);   \
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+    cfi_rel_offset(lr,SCV_FRAME_SIZE+FRAME_LR_SAVE); \
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     .machine "push"; \
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     .machine "power9"; \
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     scv 0; \
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     .machine "pop"; \
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-    ld r9,FRAME_LR_SAVE(r1); \
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+    ld r9,SCV_FRAME_SIZE+FRAME_LR_SAVE(r1);      \
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     mtlr r9; \
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     cfi_restore(lr);
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