lscpu: clean up vmware inline asm

This code is not PIC clean which means it fails to build on hardened
32bit x86 systems (i.e. building as PIE).

While here, optimize the existing cpuid logic slightly.

URL: https://bugs.gentoo.org/518936
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

diff --git a/sys-utils/lscpu.c b/sys-utils/lscpu.c
index 062dff5018868e55d3c88b53ed5e71aab1b08adf..9965eeb65ca327e6376fad36f12a569018b6d6d2 100644 (file)
--- a/sys-utils/lscpu.c
+++ b/sys-utils/lscpu.c
@@ -546,10 +546,9 @@ cpuid(unsigned int op, unsigned int *eax, unsigned int *ebx,
        __asm__(
 #if defined(__PIC__) && defined(__i386__)
                /* x86 PIC cannot clobber ebx -- gcc bitches */
-               "pushl %%ebx;"
+               "xchg %%ebx, %%esi;"
                "cpuid;"
-               "movl %%ebx, %%esi;"
-               "popl %%ebx;"
+               "xchg %%esi, %%ebx;"
                : "=S" (*ebx),
 #else
                "cpuid;"
@@ -656,12 +655,29 @@ read_hypervisor_powerpc(struct lscpu_desc *desc)
 #define VMWARE_BDOOR_PORT           0x5658
 #define VMWARE_BDOOR_CMD_GETVERSION 10
 
-#define VMWARE_BDOOR(eax, ebx, ecx, edx)                                  \
-        __asm__("inl (%%dx), %%eax" :                                     \
-               "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :               \
-               "0"(VMWARE_BDOOR_MAGIC), "1"(VMWARE_BDOOR_CMD_GETVERSION), \
-               "2"(VMWARE_BDOOR_PORT), "3"(0) :                           \
-               "memory");
+static inline
+void vmware_bdoor(uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx)
+{
+       __asm__(
+#if defined(__PIC__) && defined(__i386__)
+               /* x86 PIC cannot clobber ebx -- gcc bitches */
+               "xchg %%ebx, %%esi;"
+               "inl (%%dx), %%eax;"
+               "xchg %%esi, %%ebx;"
+               : "=S" (*ebx),
+#else
+               "inl (%%dx), %%eax;"
+               : "=b" (*ebx),
+#endif
+                 "=a" (*eax),
+                 "=c" (*ecx),
+                 "=d" (*edx)
+               : "0" (VMWARE_BDOOR_MAGIC),
+                 "1" (VMWARE_BDOOR_CMD_GETVERSION),
+                 "2" (VMWARE_BDOOR_PORT),
+                 "3" (0)
+               : "memory");
+}
 
 static jmp_buf segv_handler_env;
 
@@ -697,7 +713,7 @@ is_vmware_platform(void)
        if (sigaction(SIGSEGV, &act, &oact))
                err(EXIT_FAILURE, _("error: can not set signal handler"));
 
-       VMWARE_BDOOR(eax, ebx, ecx, edx);
+       vmware_bdoor(&eax, &ebx, &ecx, &edx);
 
        if (sigaction(SIGSEGV, &oact, NULL))
                err(EXIT_FAILURE, _("error: can not restore signal handler"));