3571e53040
patches for easier mirroring, to eliminate a special copy, to make www.freebsd.org/security a full copy of security.freebsd.org and be eventually be the same. For now files are just sitting there. The symlinks are missing. Discussed on: www (repository location) Discussed with: simon (so)
70 lines
1.8 KiB
Diff
70 lines
1.8 KiB
Diff
Index: sys/i386/isa/npx.c
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===================================================================
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RCS file: /home/ncvs/src/sys/i386/isa/npx.c,v
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retrieving revision 1.80.2.3
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diff -u -I__FBSDID -r1.80.2.3 npx.c
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--- sys/i386/isa/npx.c 20 Oct 2001 19:04:38 -0000 1.80.2.3
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+++ sys/i386/isa/npx.c 16 Apr 2006 21:10:59 -0000
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@@ -137,6 +137,10 @@
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typedef u_char bool_t;
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+#ifdef CPU_ENABLE_SSE
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+static void fpu_clean_state(void);
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+#endif
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+
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static int npx_attach __P((device_t dev));
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void npx_intr __P((void *));
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static void npx_identify __P((driver_t *driver, device_t parent));
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@@ -914,15 +918,49 @@
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fnsave(addr);
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}
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+#ifdef CPU_ENABLE_SSE
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+/*
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+ * On AuthenticAMD processors, the fxrstor instruction does not restore
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+ * the x87's stored last instruction pointer, last data pointer, and last
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+ * opcode values, except in the rare case in which the exception summary
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+ * (ES) bit in the x87 status word is set to 1.
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+ *
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+ * In order to avoid leaking this information across processes, we clean
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+ * these values by performing a dummy load before executing fxrstor().
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+ */
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+static double dummy_variable = 0.0;
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+static void
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+fpu_clean_state(void)
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+{
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+ u_short status;
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+
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+ /*
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+ * Clear the ES bit in the x87 status word if it is currently
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+ * set, in order to avoid causing a fault in the upcoming load.
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+ */
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+ fnstsw(&status);
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+ if (status & 0x80)
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+ fnclex();
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+
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+ /*
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+ * Load the dummy variable into the x87 stack. This mangles
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+ * the x87 stack, but we don't care since we're about to call
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+ * fxrstor() anyway.
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+ */
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+ __asm __volatile("ffree %%st(7); fld %0" : : "m" (dummy_variable));
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+}
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+#endif /* CPU_ENABLE_SSE */
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+
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static void
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fpurstor(addr)
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union savefpu *addr;
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{
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#ifdef CPU_ENABLE_SSE
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- if (cpu_fxsr)
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+ if (cpu_fxsr) {
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+ fpu_clean_state();
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fxrstor(addr);
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- else
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+ } else
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#endif
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frstor(addr);
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}
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