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linux-user/i386: Emulate orig_ax

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The kernel uses orig_rax/orig_eax to store the syscall number before
a syscall. One can see this value in core dumps and ptrace.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-ID: <20240912093012.402366-3-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Ilya Leoshkevich 2024-09-12 11:28:21 +02:00 • committed by Richard Henderson
parent f781af3b14
commit 3674bfadb5
3 changed files with 9 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

4
linux-user/elfload.c
View file

@ -203,7 +203,7 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs, const CPUX86State *en
(*regs)[12] = tswapreg(env->regs[R_EDX]); (*regs)[12] = tswapreg(env->regs[R_EDX]);
(*regs)[13] = tswapreg(env->regs[R_ESI]); (*regs)[13] = tswapreg(env->regs[R_ESI]);
(*regs)[14] = tswapreg(env->regs[R_EDI]); (*regs)[14] = tswapreg(env->regs[R_EDI]);
(*regs)[15] = tswapreg(env->regs[R_EAX]); /* XXX */ (*regs)[15] = tswapreg(get_task_state(env_cpu_const(env))->orig_ax);
(*regs)[16] = tswapreg(env->eip); (*regs)[16] = tswapreg(env->eip);
(*regs)[17] = tswapreg(env->segs[R_CS].selector & 0xffff); (*regs)[17] = tswapreg(env->segs[R_CS].selector & 0xffff);
(*regs)[18] = tswapreg(env->eflags); (*regs)[18] = tswapreg(env->eflags);
@ -306,7 +306,7 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs, const CPUX86State *en
(*regs)[8] = tswapreg(env->segs[R_ES].selector & 0xffff); (*regs)[8] = tswapreg(env->segs[R_ES].selector & 0xffff);
(*regs)[9] = tswapreg(env->segs[R_FS].selector & 0xffff); (*regs)[9] = tswapreg(env->segs[R_FS].selector & 0xffff);
(*regs)[10] = tswapreg(env->segs[R_GS].selector & 0xffff); (*regs)[10] = tswapreg(env->segs[R_GS].selector & 0xffff);
(*regs)[11] = tswapreg(env->regs[R_EAX]); /* XXX */ (*regs)[11] = tswapreg(get_task_state(env_cpu_const(env))->orig_ax);
(*regs)[12] = tswapreg(env->eip); (*regs)[12] = tswapreg(env->eip);
(*regs)[13] = tswapreg(env->segs[R_CS].selector & 0xffff); (*regs)[13] = tswapreg(env->segs[R_CS].selector & 0xffff);
(*regs)[14] = tswapreg(env->eflags); (*regs)[14] = tswapreg(env->eflags);

3
linux-user/i386/cpu_loop.c
View file

@ -172,6 +172,7 @@ static void emulate_vsyscall(CPUX86State *env)
/* /*
* Perform the syscall. None of the vsyscalls should need restarting. * Perform the syscall. None of the vsyscalls should need restarting.
*/ */
get_task_state(env_cpu(env))->orig_ax = syscall;
ret = do_syscall(env, syscall, env->regs[R_EDI], env->regs[R_ESI], ret = do_syscall(env, syscall, env->regs[R_EDI], env->regs[R_ESI],
env->regs[R_EDX], env->regs[10], env->regs[8], env->regs[R_EDX], env->regs[10], env->regs[8],
env->regs[9], 0, 0); env->regs[9], 0, 0);
@ -221,6 +222,7 @@ void cpu_loop(CPUX86State *env)
case EXCP_SYSCALL: case EXCP_SYSCALL:
#endif #endif
/* linux syscall from int $0x80 */ /* linux syscall from int $0x80 */
get_task_state(cs)->orig_ax = env->regs[R_EAX];
ret = do_syscall(env, ret = do_syscall(env,
env->regs[R_EAX], env->regs[R_EAX],
env->regs[R_EBX], env->regs[R_EBX],
@ -239,6 +241,7 @@ void cpu_loop(CPUX86State *env)
#ifdef TARGET_X86_64 #ifdef TARGET_X86_64
case EXCP_SYSCALL: case EXCP_SYSCALL:
/* linux syscall from syscall instruction. */ /* linux syscall from syscall instruction. */
get_task_state(cs)->orig_ax = env->regs[R_EAX];
ret = do_syscall(env, ret = do_syscall(env,
env->regs[R_EAX], env->regs[R_EAX],
env->regs[R_EDI], env->regs[R_EDI],

4
linux-user/qemu.h
View file

@ -113,6 +113,10 @@ struct TaskState {
struct target_vm86plus_struct vm86plus; struct target_vm86plus_struct vm86plus;
uint32_t v86flags; uint32_t v86flags;
uint32_t v86mask; uint32_t v86mask;
#endif
#if defined(TARGET_I386)
/* Last syscall number. */
target_ulong orig_ax;
#endif #endif
abi_ulong child_tidptr; abi_ulong child_tidptr;
#ifdef TARGET_M68K #ifdef TARGET_M68K