glibc/sysdeps/unix/sysv/linux/i386/ucontext_i.sym
H.J. Lu 15eab1e3e8 i386: Don't unnecessarily save and restore EAX, ECX and EDX [BZ# 25262]
On i386, since EAX, ECX and EDX are caller-saved, there are no need
to save and restore EAX, ECX and EDX in getcontext, setcontext and
swapcontext.  They just need to clear EAX on success.  The extra
scratch registers are needed to enable CET.

Tested on i386.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2020-02-01 05:44:55 -08:00

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#include <stddef.h>
#include <signal.h>
#include <sys/ucontext.h>
--
SIG_BLOCK
SIG_SETMASK
#define ucontext(member) offsetof (ucontext_t, member)
#define mcontext(member) ucontext (uc_mcontext.member)
#define mreg(reg) mcontext (gregs[REG_##reg])
oLINK ucontext (uc_link)
oSS_SP ucontext (uc_stack.ss_sp)
oSS_SIZE ucontext (uc_stack.ss_size)
oGS mreg (GS)
oFS mreg (FS)
oEDI mreg (EDI)
oESI mreg (ESI)
oEBP mreg (EBP)
oESP mreg (ESP)
oEBX mreg (EBX)
oEIP mreg (EIP)
oFPREGS mcontext (fpregs)
oSIGMASK ucontext (uc_sigmask)
oFPREGSMEM ucontext (__fpregs_mem)