x86/paravirt: don't restore second return reg (e584f559) · Commits · 戴 / test

Impact: bugfix In the 32-bit calling convention, %eax:%edx is used to return 64-bit values. Don't save and restore %edx around wrapped functions, or they can't return a full 64-bit result. Signed-off-by:

Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by:

H. Peter Anvin <hpa@zytor.com>

arch/x86/include/asm/paravirt.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -1524,8 +1524,8 @@ extern struct paravirt_patch_site __parainstructions[],
		#define PV_RESTORE_REGS "popl %edx; popl %ecx;"

		/* save and restore all caller-save registers, except return value */
		#define PV_SAVE_ALL_CALLER_REGS PV_SAVE_REGS
		#define PV_RESTORE_ALL_CALLER_REGS PV_RESTORE_REGS
		#define PV_SAVE_ALL_CALLER_REGS "pushl %ecx;"
		#define PV_RESTORE_ALL_CALLER_REGS "popl %ecx;"

		#define PV_FLAGS_ARG "0"
		#define PV_EXTRA_CLOBBERS

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