From: Jeremy Fitzhardinge Date: Tue, 17 Mar 2009 00:24:34 +0000 (-0700) Subject: x86, paravirt: prevent gcc from generating the wrong addressing mode X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=42854dc0a6320ff36722749acafa0697522d9556;p=openwrt%2Fstaging%2Fblogic.git x86, paravirt: prevent gcc from generating the wrong addressing mode Impact: fix crash on VMI (VMware) When we generate a call sequence for calling a paravirtualized function, we presume that the generated code is "call *0xXXXXX", which is a 6 byte opcode; this is larger than a normal direct call, and so we can patch a direct call over it. At the moment, however we give gcc enough rope to hang us by putting the address in a register and generating a two byte indirect-via-register call. Prevent this by explicitly dereferencing the function pointer and passing it into the asm as a constant. This prevents crashes in VMI, as it cannot handle unpatchable callsites. Signed-off-by: Jeremy Fitzhardinge Cc: Alok Kataria LKML-Reference: <49BEEDC2.2070809@goop.org> Signed-off-by: H. Peter Anvin --- diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index e299287e8e33..0c212d528c0a 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -360,7 +360,7 @@ extern struct pv_lock_ops pv_lock_ops; #define paravirt_type(op) \ [paravirt_typenum] "i" (PARAVIRT_PATCH(op)), \ - [paravirt_opptr] "m" (op) + [paravirt_opptr] "i" (&(op)) #define paravirt_clobber(clobber) \ [paravirt_clobber] "i" (clobber) @@ -412,7 +412,7 @@ int paravirt_disable_iospace(void); * offset into the paravirt_patch_template structure, and can therefore be * freely converted back into a structure offset. */ -#define PARAVIRT_CALL "call *%[paravirt_opptr];" +#define PARAVIRT_CALL "call *%c[paravirt_opptr];" /* * These macros are intended to wrap calls through one of the paravirt