[SeaBIOS] [PATCH 1/5] Unify smm/sloppy variants of call32_prep/post and call16_helper
Kevin O'Connor
kevin at koconnor.net
Mon Sep 14 14:26:22 CET 2015
The "smm" and "sloppy" variants of the 16bit to 32bit trampoline
backup/restore code are very similar. They can be unified into a
single copy of each function.
Signed-off-by: Kevin O'Connor <kevin at koconnor.net>
---
src/stacks.c | 132 ++++++++++++++++++++++-------------------------------------
1 file changed, 50 insertions(+), 82 deletions(-)
diff --git a/src/stacks.c b/src/stacks.c
index 708add5..339b92b 100644
--- a/src/stacks.c
+++ b/src/stacks.c
@@ -35,9 +35,9 @@ struct {
int HaveSmmCall32 VARFSEG;
-// Backup state in preparation for call32_smm()
+// Backup state in preparation for call32
static void
-call32_smm_prep(void)
+call32_prep(u8 method)
{
// Backup cmos index register and disable nmi
u8 cmosindex = inb(PORT_CMOS_INDEX);
@@ -48,19 +48,57 @@ call32_smm_prep(void)
// Backup ss
SET_LOW(Call32Data.ss, GET_SEG(SS));
- SET_LOW(Call32Data.method, C32_SMM);
+ if (!CONFIG_CALL32_SMM || method != C32_SMM) {
+ // Backup fs/gs and gdt
+ SET_LOW(Call32Data.fs, GET_SEG(FS));
+ SET_LOW(Call32Data.gs, GET_SEG(GS));
+ struct descloc_s gdt;
+ sgdt(&gdt);
+ SET_LOW(Call32Data.gdt.length, gdt.length);
+ SET_LOW(Call32Data.gdt.addr, gdt.addr);
+
+ // Enable a20 and backup its previous state
+ SET_LOW(Call32Data.a20, set_a20(1));
+ }
+
+ SET_LOW(Call32Data.method, method);
}
-// Restore state backed up during call32_smm()
-static void
-call32_smm_post(void)
+// Restore state backed up during call32
+static u8
+call32_post(void)
{
+ u8 method = GET_LOW(Call32Data.method);
SET_LOW(Call32Data.method, 0);
SET_LOW(Call32Data.ss, 0);
+ if (!CONFIG_CALL32_SMM || method != C32_SMM) {
+ // Restore a20
+ set_a20(GET_LOW(Call32Data.a20));
+
+ // Restore gdt and fs/gs
+ struct descloc_s gdt;
+ gdt.length = GET_LOW(Call32Data.gdt.length);
+ gdt.addr = GET_LOW(Call32Data.gdt.addr);
+ lgdt(&gdt);
+ SET_SEG(FS, GET_LOW(Call32Data.fs));
+ SET_SEG(GS, GET_LOW(Call32Data.gs));
+ }
+
// Restore cmos index register
outb(GET_LOW(Call32Data.cmosindex), PORT_CMOS_INDEX);
inb(PORT_CMOS_DATA);
+ return method;
+}
+
+// 16bit handler code called from call16_sloppy() / call16_smm()
+u32 VISIBLE16
+call16_helper(u32 eax, u32 edx, u32 (*func)(u32 eax, u32 edx))
+{
+ u8 method = call32_post();
+ u32 ret = func(eax, edx);
+ call32_prep(method);
+ return ret;
}
#define ASM32_SWITCH16 " .pushsection .text.32fseg." UNIQSEC "\n .code16\n"
@@ -74,7 +112,7 @@ call32_smm(void *func, u32 eax)
{
ASSERT16();
dprintf(9, "call32_smm %p %x\n", func, eax);
- call32_smm_prep();
+ call32_prep(C32_SMM);
u32 bkup_esp;
asm volatile(
// Backup esp / set esp to flat stack location
@@ -109,24 +147,12 @@ call32_smm(void *func, u32 eax)
: "=&r" (bkup_esp), "+r" (eax)
: "r" (func)
: "eax", "ecx", "edx", "ebx", "cc", "memory");
- call32_smm_post();
+ call32_post();
dprintf(9, "call32_smm done %p %x\n", func, eax);
return eax;
}
-// 16bit handler code called from call16_smm()
-u32 VISIBLE16
-call16_smm_helper(u32 eax, u32 edx, u32 (*func)(u32 eax, u32 edx))
-{
- if (!CONFIG_CALL32_SMM)
- return eax;
- call32_smm_post();
- u32 ret = func(eax, edx);
- call32_smm_prep();
- return ret;
-}
-
static u32
call16_smm(u32 eax, u32 edx, void *func)
{
@@ -151,7 +177,7 @@ call16_smm(u32 eax, u32 edx, void *func)
ASM32_SWITCH16
"1:movl %1, %%eax\n"
" movl %3, %%ecx\n"
- " calll _cfunc16_call16_smm_helper\n"
+ " calll _cfunc16_call16_helper\n"
" movl %%eax, %1\n"
" movl $" __stringify(CALL32SMM_CMDID) ", %%eax\n"
@@ -170,61 +196,13 @@ call16_smm(u32 eax, u32 edx, void *func)
return eax;
}
-// Backup state in preparation for call32_sloppy()
-static void
-call32_sloppy_prep(void)
-{
- // Backup cmos index register and disable nmi
- u8 cmosindex = inb(PORT_CMOS_INDEX);
- outb(cmosindex | NMI_DISABLE_BIT, PORT_CMOS_INDEX);
- inb(PORT_CMOS_DATA);
- SET_LOW(Call32Data.cmosindex, cmosindex);
-
- // Enable a20 and backup its previous state
- SET_LOW(Call32Data.a20, set_a20(1));
-
- // Backup ss/fs/gs and gdt
- SET_LOW(Call32Data.ss, GET_SEG(SS));
- SET_LOW(Call32Data.fs, GET_SEG(FS));
- SET_LOW(Call32Data.gs, GET_SEG(GS));
- struct descloc_s gdt;
- sgdt(&gdt);
- SET_LOW(Call32Data.gdt.length, gdt.length);
- SET_LOW(Call32Data.gdt.addr, gdt.addr);
-
- SET_LOW(Call32Data.method, C32_SLOPPY);
-}
-
-// Restore state backed up during call32_sloppy()
-static void
-call32_sloppy_post(void)
-{
- SET_LOW(Call32Data.method, 0);
- SET_LOW(Call32Data.ss, 0);
-
- // Restore gdt and fs/gs
- struct descloc_s gdt;
- gdt.length = GET_LOW(Call32Data.gdt.length);
- gdt.addr = GET_LOW(Call32Data.gdt.addr);
- lgdt(&gdt);
- SET_SEG(FS, GET_LOW(Call32Data.fs));
- SET_SEG(GS, GET_LOW(Call32Data.gs));
-
- // Restore a20
- set_a20(GET_LOW(Call32Data.a20));
-
- // Restore cmos index register
- outb(GET_LOW(Call32Data.cmosindex), PORT_CMOS_INDEX);
- inb(PORT_CMOS_DATA);
-}
-
// Call a C function in 32bit mode. This clobbers the 16bit segment
// selector registers.
static u32
call32_sloppy(void *func, u32 eax)
{
ASSERT16();
- call32_sloppy_prep();
+ call32_prep(C32_SLOPPY);
u32 bkup_ss, bkup_esp;
asm volatile(
// Backup ss/esp / set esp to flat stack location
@@ -250,20 +228,10 @@ call32_sloppy(void *func, u32 eax)
: "=&r" (bkup_ss), "=&r" (bkup_esp), "+a" (eax)
: "r" (func)
: "ecx", "edx", "cc", "memory");
- call32_sloppy_post();
+ call32_post();
return eax;
}
-// 16bit handler code called from call16_sloppy()
-u32 VISIBLE16
-call16_sloppy_helper(u32 eax, u32 edx, u32 (*func)(u32 eax, u32 edx))
-{
- call32_sloppy_post();
- u32 ret = func(eax, edx);
- call32_sloppy_prep();
- return ret;
-}
-
// Jump back to 16bit mode while in 32bit mode from call32_sloppy()
static u32
call16_sloppy(u32 eax, u32 edx, void *func)
@@ -286,7 +254,7 @@ call16_sloppy(u32 eax, u32 edx, void *func)
" movw %%cx, %%ds\n"
" movl %2, %%edx\n"
" movl %1, %%ecx\n"
- " calll _cfunc16_call16_sloppy_helper\n"
+ " calll _cfunc16_call16_helper\n"
// Return to 32bit and restore esp
" movl $2f, %%edx\n"
" jmp transition32\n"
--
2.4.3
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