On Thu, Dec 29, 2022 at 6:42 PM Ammar Faizi wrote: > On 12/28/22 8:35 PM, Willy Tarreau wrote: > > It gives me the correct code for x86_64 and i586. I don't know if other > > architectures will want to add a prologue. I tried with "naked" but it's > > ignored by the compiler since the function is not purely asm. Not very > > important but given that we already have everything to perform our calls > > it would make sense to stay on this. By the way, for the sake of > > consistency with other syscalls, I do think the function (or label if > > we can't do otherwise) should be called "sys_rt_sigreturn" as it just > > performs a syscall. > > Will call that 'sys_rt_sigreturn' in the next series. >From glibc source code says: GDB needs some intimate knowledge about it to recognize them as signal trampolines, and make backtraces through signal handlers work right. Important are both the names (__restore_rt) and the exact instruction sequence. link: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/x86_64/sigaction.c;h=4e6d9cc32e1e18746726fa430d092de9a19ba6c6;hb=b4a5d26d8835d972995f0a0a2f805a8845bafa0b#l34 glibc does this: " .type __" #name ",@function\n" \ "__" #name ":\n" \ " movq $" #syscall ", %rax\n" \ " syscall\n" \ where #name = "restore_rt" #syscall = __NR_rt_sigreturn I think it should be called "__restore_rt" instead of "sys_rt_sigreturn"? glibc also has unwind information, but we probably don't need to care with that much
