From: Michael Brown <mcb30@ipxe.org>
Date: Wed, 7 May 2025 21:57:40 +0000 (+0100)
Subject: [build] Constrain PHYS_CODE() and REAL_CODE() to use i386 registers
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e8a6c2657163af1255d1b1ccff3d19c45b0a6182;p=thirdparty%2Fipxe.git

[build] Constrain PHYS_CODE() and REAL_CODE() to use i386 registers

Inline assembly using PHYS_CODE() or REAL_CODE() must use the "R"
constraint rather than the "r" constraint to ensure that the compiler
chooses registers that will be valid for the 32-bit or 16-bit assembly
code fragment.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---

diff --git a/src/arch/x86/image/com32.c b/src/arch/x86/image/com32.c
index 0c47f95e4..37fb2c3c0 100644
--- a/src/arch/x86/image/com32.c
+++ b/src/arch/x86/image/com32.c
@@ -114,13 +114,13 @@ static int com32_exec_loop ( struct image *image ) {
 			/* Restore registers */
 			"popal\n\t" )
 			:
-			: "r" ( avail_mem_top ),
-			  "r" ( virt_to_phys ( com32_cfarcall_wrapper ) ),
-			  "r" ( virt_to_phys ( com32_farcall_wrapper ) ),
-			  "r" ( get_fbms() * 1024 - ( COM32_BOUNCE_SEG << 4 ) ),
+			: "R" ( avail_mem_top ),
+			  "R" ( virt_to_phys ( com32_cfarcall_wrapper ) ),
+			  "R" ( virt_to_phys ( com32_farcall_wrapper ) ),
+			  "R" ( get_fbms() * 1024 - ( COM32_BOUNCE_SEG << 4 ) ),
 			  "i" ( COM32_BOUNCE_SEG << 4 ),
-			  "r" ( virt_to_phys ( com32_intcall_wrapper ) ),
-			  "r" ( virt_to_phys ( image->cmdline ?
+			  "R" ( virt_to_phys ( com32_intcall_wrapper ) ),
+			  "R" ( virt_to_phys ( image->cmdline ?
 					       image->cmdline : "" ) ),
 			  "i" ( COM32_START_PHYS )
 			: "memory" );
diff --git a/src/arch/x86/image/comboot.c b/src/arch/x86/image/comboot.c
index dcf9114b5..f717e1d32 100644
--- a/src/arch/x86/image/comboot.c
+++ b/src/arch/x86/image/comboot.c
@@ -171,7 +171,7 @@ static int comboot_exec_loop ( struct image *image ) {
 				    "xorw %%di, %%di\n\t"
 				    "xorw %%bp, %%bp\n\t"
 				    "lret\n\t" )
-					 : : "r" ( COMBOOT_PSP_SEG ) : "eax" );
+					 : : "R" ( COMBOOT_PSP_SEG ) : "eax" );
 		DBGC ( image, "COMBOOT %p: returned\n", image );
 		break;
 
diff --git a/src/arch/x86/interface/pcbios/bios_mp.c b/src/arch/x86/interface/pcbios/bios_mp.c
index 9e1179ccd..c903a81fc 100644
--- a/src/arch/x86/interface/pcbios/bios_mp.c
+++ b/src/arch/x86/interface/pcbios/bios_mp.c
@@ -92,9 +92,9 @@ static void bios_mp_exec_boot ( mp_func_t func, void *opaque ) {
 					   "pushl %k1\n\t"
 					   "call *%k0\n\t"
 					   "addl $8, %%esp\n\t" )
-			       : : "r" ( mp_address ( mp_call ) ),
-				   "r" ( mp_address ( func ) ),
-				   "r" ( mp_address ( opaque ) ) );
+			       : : "R" ( mp_address ( mp_call ) ),
+				   "R" ( mp_address ( func ) ),
+				   "R" ( mp_address ( opaque ) ) );
 }
 
 /**
diff --git a/src/arch/x86/interface/syslinux/comboot_call.c b/src/arch/x86/interface/syslinux/comboot_call.c
index 714807f7a..f7cceb30f 100644
--- a/src/arch/x86/interface/syslinux/comboot_call.c
+++ b/src/arch/x86/interface/syslinux/comboot_call.c
@@ -514,8 +514,8 @@ static __asmcall __used void int22 ( struct i386_all_regs *ix86 ) {
 				"lret\n\t"
 			)
 			:
-			: "r" ( ix86->segs.ds ),
-			  "r" ( ix86->regs.ebp ),
+			: "R" ( ix86->segs.ds ),
+			  "R" ( ix86->regs.ebp ),
 			  "d" ( ix86->regs.ebx ),
 			  "S" ( ix86->regs.esi ) );