[hurd,commited] hurd: Fix unwinding over INTR_MSG_TRAP

[Samuel Thibault]

We used to use .cfi_adjust_cfa_offset around %esp manipulation
asm instructions to fix unwinding, but when building glibc with
-fno-omit-frame-pointer this is bogus since in that case %ebp is the CFA and
does not move.

Instead, let's force -fno-omit-frame-pointer when building intr-msg.c so
that %ebp can always be used and no .cfi_adjust_cfa_offset is needed.
---
 hurd/Makefile                     |  3 +++
 sysdeps/mach/hurd/i386/intr-msg.h | 13 -------------
 2 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/hurd/Makefile b/hurd/Makefile
index 77cb16cdf7..7c34e9ad0d 100644
--- a/hurd/Makefile
+++ b/hurd/Makefile
@@ -89,6 +89,9 @@ generated += $(inlines:=.c)
 # Avoid ssp before TLS is initialized.
 CFLAGS-hurdstartup.o = $(no-stack-protector)
 CFLAGS-RPC_exec_startup_get_info.o = $(no-stack-protector)
+
+# Make it simpler to unwind over INTR_MSG_TRAP
+CFLAGS-intr-msg.o = -fno-omit-frame-pointer
 
 # Make generated headers compatible with all support standards
 migheaderpipe := | sed -e 's/\<ino64_t\>/__ino64_t/' -e 
's/\<loff_t\>/__loff_t/'
diff --git a/sysdeps/mach/hurd/i386/intr-msg.h 
b/sysdeps/mach/hurd/i386/intr-msg.h
index 58f2f37c17..29cb4620da 100644
--- a/sysdeps/mach/hurd/i386/intr-msg.h
+++ b/sysdeps/mach/hurd/i386/intr-msg.h
@@ -41,21 +41,13 @@
        "_hurd_intr_rpc_msg_do:"                                                
      \
        /* Ok, push the mach_msg_trap arguments.  */                          \
        "                               pushl 24(%4)\n"                       \
-       "                               .cfi_adjust_cfa_offset 4\n"           \
        "                               pushl %2\n"                           \
-       "                               .cfi_adjust_cfa_offset 4\n"           \
        "                               pushl 16(%4)\n"                       \
-       "                               .cfi_adjust_cfa_offset 4\n"           \
        "                               pushl 12(%4)\n"                       \
-       "                               .cfi_adjust_cfa_offset 4\n"           \
        "                               pushl 8(%4)\n"                        \
-       "                               .cfi_adjust_cfa_offset 4\n"           \
        "                               pushl %1\n"                           \
-       "                               .cfi_adjust_cfa_offset 4\n"           \
        "                               pushl (%4)\n"                         \
-       "                               .cfi_adjust_cfa_offset 4\n"           \
        "                               pushl $0\n"                           \
-       "                               .cfi_adjust_cfa_offset 4\n"           \
        /* TODO: remove this ecx kludge, we don't need it any more */         \
        "                               movl %%esp, %%ecx\n"                  \
        "_hurd_intr_rpc_msg_cx_sp:      movl $-25, %%eax\n"                   \
@@ -63,15 +55,10 @@
        "_hurd_intr_rpc_msg_in_trap:"                                         \
        /* Ok, clean the arguments and update OPTION and TIMEOUT.  */         \
        "                               addl $8, %%esp\n"                     \
-       "                               .cfi_adjust_cfa_offset -8\n"          \
        "                               popl %1\n"                            \
-       "                               .cfi_adjust_cfa_offset -4\n"          \
        "                               addl $12, %%esp\n"                    \
-       "                               .cfi_adjust_cfa_offset -12\n"         \
        "                               popl %2\n"                            \
-       "                               .cfi_adjust_cfa_offset -4\n"          \
        "                               addl $4, %%esp\n"                     \
-       "                               .cfi_adjust_cfa_offset -4\n"          \
        "_hurd_intr_rpc_msg_sp_restored:"                                     \
        : "=a" (err), "+r" (option), "+r" (timeout), "=m" (*intr_port_p)        
      \
        : "r" (&msg), "m" (*cancel_p), "i" (EINTR)                            \
-- 
2.39.1