[glibc/release/2.34/master] powerpc64[le]: Fix CFI and LR save address for asm syscalls [BZ #28532]

[Matheus Castanho]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=387bff63dc2dccd62b09aa26dccf8cdc5f3c985c

commit 387bff63dc2dccd62b09aa26dccf8cdc5f3c985c
Author: Matheus Castanho <msc@linux.ibm.com>
Date:   Tue Oct 26 10:44:59 2021 -0300

    powerpc64[le]: Fix CFI and LR save address for asm syscalls [BZ #28532]
    
    Syscalls based on the assembly templates are missing CFI for r31, which gets
    clobbered when scv is used, and info for LR is inaccurate, placed in the wrong
    LOC and not using the proper offset. LR was also being saved to the callee's
    frame, while the ABI mandates it to be saved to the caller's frame. These are
    fixed by this commit.
    
    After this change:
    
    $ readelf -wF libc.so.6 | grep 0004b9d4.. -A 7 && objdump --disassemble=kill libc.so.6
    00004a48 0000000000000020 00004a4c FDE cie=00000000 pc=000000000004b9d4..000000000004ba3c
       LOC           CFA      r31   ra
    000000000004b9d4 r1+0     u     u
    000000000004b9e4 r1+48    u     u
    000000000004b9e8 r1+48    c-16  u
    000000000004b9fc r1+48    c-16  c+16
    000000000004ba08 r1+48    c-16
    000000000004ba18 r1+48    u
    000000000004ba1c r1+0     u
    
    libc.so.6:     file format elf64-powerpcle
    
    Disassembly of section .text:
    
    000000000004b9d4 <kill>:
       4b9d4:       1f 00 4c 3c     addis   r2,r12,31
       4b9d8:       2c c3 42 38     addi    r2,r2,-15572
       4b9dc:       25 00 00 38     li      r0,37
       4b9e0:       d1 ff 21 f8     stdu    r1,-48(r1)
       4b9e4:       20 00 e1 fb     std     r31,32(r1)
       4b9e8:       98 8f ed eb     ld      r31,-28776(r13)
       4b9ec:       10 00 ff 77     andis.  r31,r31,16
       4b9f0:       1c 00 82 41     beq     4ba0c <kill+0x38>
       4b9f4:       a6 02 28 7d     mflr    r9
       4b9f8:       40 00 21 f9     std     r9,64(r1)
       4b9fc:       01 00 00 44     scv     0
       4ba00:       40 00 21 e9     ld      r9,64(r1)
       4ba04:       a6 03 28 7d     mtlr    r9
       4ba08:       08 00 00 48     b       4ba10 <kill+0x3c>
       4ba0c:       02 00 00 44     sc
       4ba10:       00 00 bf 2e     cmpdi   cr5,r31,0
       4ba14:       20 00 e1 eb     ld      r31,32(r1)
       4ba18:       30 00 21 38     addi    r1,r1,48
       4ba1c:       18 00 96 41     beq     cr5,4ba34 <kill+0x60>
       4ba20:       01 f0 20 39     li      r9,-4095
       4ba24:       40 48 23 7c     cmpld   r3,r9
       4ba28:       20 00 e0 4d     bltlr+
       4ba2c:       d0 00 63 7c     neg     r3,r3
       4ba30:       08 00 00 48     b       4ba38 <kill+0x64>
       4ba34:       20 00 e3 4c     bnslr+
       4ba38:       c8 32 fe 4b     b       2ed00 <__syscall_error>
            ...
       4ba44:       40 20 0c 00     .long 0xc2040
       4ba48:       68 00 00 00     .long 0x68
       4ba4c:       06 00 5f 5f     rlwnm   r31,r26,r0,0,3
       4ba50:       6b 69 6c 6c     xoris   r12,r3,26987
    
    (cherry picked from commit d120fb9941be1fb1934f0b50c6ad64e4c5e404fb)

Diff:
---
 NEWS                               |  1 +
 sysdeps/powerpc/powerpc64/sysdep.h | 10 ++++++----
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/NEWS b/NEWS
index b352a92704..8c68273929 100644
--- a/NEWS
+++ b/NEWS
@@ -20,6 +20,7 @@ The following bugs are resolved with this release:
   [28407] pthread_kill assumes that kill and tgkill are equivalent
   [28524] Conversion from ISO-2022-JP-3 with iconv may emit spurious NULs
   [28607] Masked signals are delivered on thread exit
+  [28532] powerpc64[le]: CFI for assembly templated syscalls is incorrect
 
 
 Version 2.34
diff --git a/sysdeps/powerpc/powerpc64/sysdep.h b/sysdeps/powerpc/powerpc64/sysdep.h
index 589f7c8d18..cfcfa69f91 100644
--- a/sysdeps/powerpc/powerpc64/sysdep.h
+++ b/sysdeps/powerpc/powerpc64/sysdep.h
@@ -275,12 +275,14 @@ LT_LABELSUFFIX(name,_name_end): ; \
 /* Allocate frame and save register */
 #define NVOLREG_SAVE \
     stdu r1,-SCV_FRAME_SIZE(r1); \
+    cfi_adjust_cfa_offset(SCV_FRAME_SIZE); \
     std r31,SCV_FRAME_NVOLREG_SAVE(r1); \
-    cfi_adjust_cfa_offset(SCV_FRAME_SIZE);
+    cfi_rel_offset(r31,SCV_FRAME_NVOLREG_SAVE);
 
 /* Restore register and destroy frame */
 #define NVOLREG_RESTORE	\
     ld r31,SCV_FRAME_NVOLREG_SAVE(r1); \
+    cfi_restore(r31); \
     addi r1,r1,SCV_FRAME_SIZE; \
     cfi_adjust_cfa_offset(-SCV_FRAME_SIZE);
 
@@ -331,13 +333,13 @@ LT_LABELSUFFIX(name,_name_end): ; \
 
 #define DO_CALL_SCV \
     mflr r9; \
-    std r9,FRAME_LR_SAVE(r1); \
-    cfi_offset(lr,FRAME_LR_SAVE); \
+    std r9,SCV_FRAME_SIZE+FRAME_LR_SAVE(r1);   \
+    cfi_rel_offset(lr,SCV_FRAME_SIZE+FRAME_LR_SAVE); \
     .machine "push"; \
     .machine "power9"; \
     scv 0; \
     .machine "pop"; \
-    ld r9,FRAME_LR_SAVE(r1); \
+    ld r9,SCV_FRAME_SIZE+FRAME_LR_SAVE(r1);      \
     mtlr r9; \
     cfi_restore(lr);