While we don't mean to run their objtool over our generated code, it still seems desirable to avoid calls to further functions before a function's frame pointer is set up.
Suggested-by: Andrew Cooper <andrew.coop...@citrix.com> Signed-off-by: Jan Beulich <jbeul...@suse.com> Reviewed-by: Wei Liu <wei.l...@citrix.com> --- v6: Fix build issue with old gcc. v5: New. --- a/xen/arch/x86/efi/stub.c +++ b/xen/arch/x86/efi/stub.c @@ -2,8 +2,9 @@ #include <xen/errno.h> #include <xen/init.h> #include <xen/lib.h> -#include <asm/page.h> +#include <asm/asm_defns.h> #include <asm/efibind.h> +#include <asm/page.h> #include <efi/efidef.h> #include <efi/eficapsule.h> #include <efi/eficon.h> @@ -34,10 +35,11 @@ void __init noreturn efi_multiboot2(EFI_ * not be directly supported by C compiler. */ asm volatile( - " call *%3 \n" + " call *%[outstr] \n" "0: hlt \n" " jmp 0b \n" - : "+c" (StdErr), "=d" (StdErr) : "1" (err), "rm" (StdErr->OutputString) + : "+c" (StdErr), "=d" (StdErr) ASM_CALL_CONSTRAINT + : "1" (err), [outstr] "rm" (StdErr->OutputString) : "rax", "r8", "r9", "r10", "r11", "memory"); unreachable(); --- a/xen/arch/x86/extable.c +++ b/xen/arch/x86/extable.c @@ -168,7 +168,7 @@ static int __init stub_selftest(void) "jmp .Lret%=\n\t" ".popsection\n\t" _ASM_EXTABLE(.Lret%=, .Lfix%=) - : [exn] "+m" (res) + : [exn] "+m" (res) ASM_CALL_CONSTRAINT : [stb] "r" (addr), "a" (tests[i].rax)); if ( res.raw != tests[i].res.raw ) --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -1101,7 +1101,8 @@ static inline int mkec(uint8_t e, int32_ "jmp .Lret%=\n\t" \ ".popsection\n\t" \ _ASM_EXTABLE(.Lret%=, .Lfix%=) \ - : [exn] "+g" (stub_exn.info), constraints, \ + : [exn] "+g" (stub_exn.info) ASM_CALL_CONSTRAINT, \ + constraints, \ [stub] "r" (stub.func), \ "m" (*(uint8_t(*)[MAX_INST_LEN + 1])stub.ptr) ); \ if ( unlikely(~stub_exn.info.raw) ) \ --- a/xen/include/asm-x86/asm_defns.h +++ b/xen/include/asm-x86/asm_defns.h @@ -25,6 +25,19 @@ asm ( "\t.equ CONFIG_INDIRECT_THUNK, " #ifndef __ASSEMBLY__ void ret_from_intr(void); + +/* + * This output constraint should be used for any inline asm which has a "call" + * instruction. Otherwise the asm may be inserted before the frame pointer + * gets set up by the containing function. + */ +#ifdef CONFIG_FRAME_POINTER +register unsigned long current_stack_pointer asm("rsp"); +# define ASM_CALL_CONSTRAINT , "+r" (current_stack_pointer) +#else +# define ASM_CALL_CONSTRAINT +#endif + #endif #ifndef NDEBUG --- a/xen/include/asm-x86/guest/hypercall.h +++ b/xen/include/asm-x86/guest/hypercall.h @@ -40,7 +40,7 @@ long res, tmp__; \ asm volatile ( \ "call hypercall_page + %c[offset]" \ - : "=a" (res), "=D" (tmp__) \ + : "=a" (res), "=D" (tmp__) ASM_CALL_CONSTRAINT \ : [offset] "i" (hcall * 32), \ "1" ((long)(a1)) \ : "memory" ); \ @@ -53,6 +53,7 @@ asm volatile ( \ "call hypercall_page + %c[offset]" \ : "=a" (res), "=D" (tmp__), "=S" (tmp__) \ + ASM_CALL_CONSTRAINT \ : [offset] "i" (hcall * 32), \ "1" ((long)(a1)), "2" ((long)(a2)) \ : "memory" ); \ @@ -65,6 +66,7 @@ asm volatile ( \ "call hypercall_page + %c[offset]" \ : "=a" (res), "=D" (tmp__), "=S" (tmp__), "=d" (tmp__) \ + ASM_CALL_CONSTRAINT \ : [offset] "i" (hcall * 32), \ "1" ((long)(a1)), "2" ((long)(a2)), "3" ((long)(a3)) \ : "memory" ); \ @@ -78,7 +80,7 @@ asm volatile ( \ "call hypercall_page + %c[offset]" \ : "=a" (res), "=D" (tmp__), "=S" (tmp__), "=d" (tmp__), \ - "=&r" (tmp__) \ + "=&r" (tmp__) ASM_CALL_CONSTRAINT \ : [offset] "i" (hcall * 32), \ "1" ((long)(a1)), "2" ((long)(a2)), "3" ((long)(a3)), \ "4" (_a4) \ _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel