um: Allow building and running on older hosts

Commit a78ff1112263 ("um: add extended processor state save/restore
support") and b6024b21fec8 ("um: extend fpstate to _xstate to support
YMM registers") forced the use of the x86 FP _xstate and
PTRACE_GETREGSET/SETREGSET. On older hosts, we would neither be able to
build UML nor run it anymore with these two commits applied because we
don't have definitions for struct _xstate nor these two ptrace requests.

We can determine at build time which fp context structure to check
against, just like we can keep using the old i387 fp save/restore if
PTRACE_GETRESET/SETREGSET are not defined.

Fixes: a78ff1112263 ("um: add extended processor state save/restore support")
Fixes: b6024b21fec8 ("um: extend fpstate to _xstate to support YMM registers")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/arch/x86/um/os-Linux/registers.c b/arch/x86/um/os-Linux/registers.c
index 00f54a91bb4b06ae29d9b643a815e00de9c5c6a5..28775f55bde240fc29fcc2030748e2078c0747c5 100644 (file)
--- a/arch/x86/um/os-Linux/registers.c
+++ b/arch/x86/um/os-Linux/registers.c
@@ -26,6 +26,7 @@ int save_i387_registers(int pid, unsigned long *fp_regs)
 
 int save_fp_registers(int pid, unsigned long *fp_regs)
 {
+#ifdef PTRACE_GETREGSET
        struct iovec iov;
 
        if (have_xstate_support) {
@@ -34,9 +35,9 @@ int save_fp_registers(int pid, unsigned long *fp_regs)
                if (ptrace(PTRACE_GETREGSET, pid, NT_X86_XSTATE, &iov) < 0)
                        return -errno;
                return 0;
-       } else {
+       } else
+#endif
                return save_i387_registers(pid, fp_regs);
-       }
 }
 
 int restore_i387_registers(int pid, unsigned long *fp_regs)
@@ -48,6 +49,7 @@ int restore_i387_registers(int pid, unsigned long *fp_regs)
 
 int restore_fp_registers(int pid, unsigned long *fp_regs)
 {
+#ifdef PTRACE_SETREGSET
        struct iovec iov;
 
        if (have_xstate_support) {
@@ -56,9 +58,9 @@ int restore_fp_registers(int pid, unsigned long *fp_regs)
                if (ptrace(PTRACE_SETREGSET, pid, NT_X86_XSTATE, &iov) < 0)
                        return -errno;
                return 0;
-       } else {
+       } else
+#endif
                return restore_i387_registers(pid, fp_regs);
-       }
 }
 
 #ifdef __i386__
@@ -122,6 +124,7 @@ int put_fp_registers(int pid, unsigned long *regs)
 
 void arch_init_registers(int pid)
 {
+#ifdef PTRACE_GETREGSET
        struct _xstate fp_regs;
        struct iovec iov;
 
@@ -129,6 +132,7 @@ void arch_init_registers(int pid)
        iov.iov_len = sizeof(struct _xstate);
        if (ptrace(PTRACE_GETREGSET, pid, NT_X86_XSTATE, &iov) == 0)
                have_xstate_support = 1;
+#endif
 }
 #endif
 

diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
index cb3c22370cf58bdf25e2ce895371eb5c7ab9597a..8af0fb5d27807a6b6abbec51622449723a8bf816 100644 (file)
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -50,7 +50,11 @@ void foo(void)
        DEFINE(HOST_GS, GS);
        DEFINE(HOST_ORIG_AX, ORIG_EAX);
 #else
+#if defined(PTRACE_GETREGSET) && defined(PTRACE_SETREGSET)
        DEFINE(HOST_FP_SIZE, sizeof(struct _xstate) / sizeof(unsigned long));
+#else
+       DEFINE(HOST_FP_SIZE, sizeof(struct _fpstate) / sizeof(unsigned long));
+#endif
        DEFINE_LONGS(HOST_BX, RBX);
        DEFINE_LONGS(HOST_CX, RCX);
        DEFINE_LONGS(HOST_DI, RDI);