Introduce APM support

loader/arch/x86/bios/CMakeLists.txt

@@ -29,6 +29,7 @@ target_sources(
 target_sources(
     ${LOADER_EXECUTABLE}
     PRIVATE
+    apm.c
     bios_disk_services.c
     bios_entry.c
     bios_find.c

loader/arch/x86/bios/apm.c

@@ -0,0 +1,98 @@
+#define MSG_FMT(msg) "BIOS-APM: " msg
+
+#include "common/format.h"
+#include "common/log.h"
+#include "bios_call.h"
+#include "services_impl.h"
+#include "apm.h"
+
+#define APM_SIGNATURE 0x504D
+#define APM_POWER_DEVICE_ID_APM_BIOS 0x0000
+
+#define APM_FLAG_32BIT_INTERFACE_SUPPORTED (1 << 1)
+
+#define APM_INT 0x15
+#define APM_CMD 0x53
+#define MAKE_APM_CMD(cmd) ((APM_CMD << 8) | (cmd))
+
+#define APM_INSTALLATION_CHECK MAKE_APM_CMD(0x00)
+#define APM_PM32_INTERFACE_CONNECT MAKE_APM_CMD(0x03)
+#define APM_INTERFACE_DISCONNECT MAKE_APM_CMD(0x04)
+
+static bool check_apm_call(
+    const struct real_mode_regs *in_regs,
+    const struct real_mode_regs *out_regs
+)
+{
+    if (is_carry_set(out_regs)) {
+        print_warn(
+            "APM call 0x%04X failed: %d\n",
+            in_regs->eax, (out_regs->eax & 0xFFFF) >> 8
+        );
+        return false;
+    }
+
+    if (in_regs->eax == APM_INSTALLATION_CHECK) {
+        u16 signature = out_regs->ebx & 0xFFFF;
+
+        if (unlikely(signature != APM_SIGNATURE)) {
+            print_warn("bad APM signature 0x%04X\n", signature);
+            return false;
+        }
+    }
+
+    return true;
+}
+
+bool services_setup_apm(struct apm_info *out_info)
+{
+    struct real_mode_regs out_regs, in_regs = { 0 };
+
+    // All queries will be for the APM BIOS "device"
+    in_regs.ebx = APM_POWER_DEVICE_ID_APM_BIOS;
+
+    // 1. Check if APM exists at all
+    in_regs.eax = APM_INSTALLATION_CHECK;
+    bios_call(APM_INT, &in_regs, &out_regs);
+    if (!check_apm_call(&in_regs, &out_regs))
+        return false;
+
+    if (!(out_regs.ecx & APM_FLAG_32BIT_INTERFACE_SUPPORTED)) {
+        print_warn("APM doesn't support 32-bit interface\n");
+        return false;
+    }
+
+    // 2. Disconnect if anything was connected previously, ignore return value
+    in_regs.eax = APM_INTERFACE_DISCONNECT;
+    bios_call(APM_INT, &in_regs, &out_regs);
+
+    // 3. Connect the 32-bit interface
+    in_regs.eax = APM_PM32_INTERFACE_CONNECT;
+    bios_call(APM_INT, &in_regs, &out_regs);
+    if (!check_apm_call(&in_regs, &out_regs))
+        return false;
+
+    print_info("32-bit PM interface connected\n");
+    out_info->pm_code_segment = out_regs.eax & 0xFFFF;
+    out_info->pm_code_segment_length = out_regs.esi & 0xFFFF;
+    out_info->pm_offset = out_regs.ebx;
+
+    out_info->rm_code_segment = out_regs.ecx & 0xFFFF;
+    out_info->rm_code_segment_length = out_regs.esi >> 16;
+
+    out_info->data_segment = out_regs.edx & 0xFFFF;
+    out_info->data_segment_length = out_regs.edi & 0xFFFF;
+
+    // 4. Recheck flags, as they might change after 32-bit interface install
+    in_regs.eax = APM_INSTALLATION_CHECK;
+    bios_call(APM_INT, &in_regs, &out_regs);
+    if (unlikely(!check_apm_call(&in_regs, &out_regs))) {
+        in_regs.eax = APM_INTERFACE_DISCONNECT;
+        bios_call(APM_INT, &in_regs, &out_regs);
+        return false;
+    }
+
+    out_info->version = out_regs.eax & 0xFFFF;
+    out_info->flags = out_regs.ecx & 0xFFFF;
+    return true;
+}

loader/boot_protocol/ultra.c

@@ -458,10 +458,28 @@ static bool set_video_mode(struct config *cfg, struct loadable_entry *entry,
     return true;
 }
 
+static bool apm_setup(struct config *cfg, struct loadable_entry *le,
+                      struct apm_info *out_info)
+{
+    bool wants_apm = false;
+
+    cfg_get_bool(cfg, le, SV("setup-apm"), &wants_apm);
+    if (!wants_apm)
+        return false;
+
+    if (services_get_provider() != SERVICE_PROVIDER_BIOS) {
+        print_info("ignoring request to set up APM on UEFI\n");
+        return false;
+    }
+
+    return services_setup_apm(out_info);
+}
+
 struct attribute_array_spec {
     bool higher_half_pointers;
     bool fb_present;
     bool cmdline_present;
+    bool apm_info_present;
     uint8_t page_table_depth;
 
     struct ultra_framebuffer fb;
@@ -471,6 +489,8 @@ struct attribute_array_spec {
 
     struct dynamic_buffer module_buf;
 
+    struct apm_info apm_info;
+
     ptr_t acpi_rsdp_address;
     ptr_t dtb_address;
     ptr_t smbios_address;
@@ -595,6 +615,18 @@ static void *write_framebuffer(struct ultra_framebuffer_attribute *fb_attr,
     return ++fb_attr;
 }
 
+static void *write_apm_info(struct ultra_apm_attribute *apm_attr,
+                            const struct attribute_array_spec *spec)
+{
+    apm_attr->header.type = ULTRA_ATTRIBUTE_APM_INFO;
+    apm_attr->header.size = sizeof(struct ultra_apm_attribute);
+
+    BUILD_BUG_ON(sizeof(apm_attr->info) != sizeof(struct apm_info));
+    memcpy(&apm_attr->info, &spec->apm_info, sizeof(struct apm_info));
+
+    return ++apm_attr;
+}
+
 static void *write_memory_map(void *attr_ptr, size_t entry_count)
 {
     struct ultra_memory_map_attribute *mm = attr_ptr;
@@ -651,6 +683,8 @@ static ptr_t build_attribute_array(const struct attribute_array_spec *spec,
     bytes_needed += cmdline_aligned_length;
     bytes_needed += spec->fb_present *
                         sizeof(struct ultra_framebuffer_attribute);
+    bytes_needed += spec->apm_info_present *
+                        sizeof(struct ultra_apm_attribute);
     bytes_needed += sizeof(struct ultra_memory_map_attribute);
 
     // Add 2 to give some leeway for memory map growth after the next allocation
@@ -725,6 +759,11 @@ static ptr_t build_attribute_array(const struct attribute_array_spec *spec,
         *attr_count += 1;
     }
 
+    if (spec->apm_info_present) {
+        attr_ptr = write_apm_info(attr_ptr, spec);
+        *attr_count += 1;
+    }
+
     attr_ptr = write_memory_map(attr_ptr, mm_entry_count);
     *attr_count += 1;
     return ret;
@@ -1140,6 +1179,8 @@ static void ultra_protocol_boot(struct config *cfg, struct loadable_entry *le)
     spec.dtb_address = services_find_dtb();
     spec.smbios_address = services_find_smbios();
 
+    spec.apm_info_present = apm_setup(cfg, le, &spec.apm_info);
+
    /*
     * Attempt to set video mode last, as we're not going to be able to use
     * legacy tty logging after that.

loader/include/apm.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include "common/types.h"
+
+struct apm_info {
+    u16 version;
+    u16 flags;
+
+    u16 pm_code_segment;
+    u16 pm_code_segment_length;
+    u32 pm_offset;
+
+    u16 rm_code_segment;
+    u16 rm_code_segment_length;
+
+    u16 data_segment;
+    u16 data_segment_length;
+};

loader/include/services.h

@@ -2,6 +2,7 @@
 
 #include "common/types.h"
 #include "common/attributes.h"
+#include "apm.h"
 
 enum service_provider {
     SERVICE_PROVIDER_INVALID,
@@ -28,6 +29,12 @@ ptr_t services_find_dtb(void);
  */
 ptr_t services_find_smbios(void);
 
+/*
+ * Attempts to setup the 32-bit protected-mode interface for APM if it exists.
+ * Returns true if the interface was successfully installed, false otherwise.
+ */
+bool services_setup_apm(struct apm_info *out_info);
+
 /*
  * Aborts the loader execution in a platform-specific manner.
  * Must be used for unrecoverable errors.

loader/uefi/CMakeLists.txt

@@ -34,4 +34,5 @@ target_sources(
     uefi_memory_services.c
     uefi_video_services.c
     relocator.c
+    stubs.c
 )

loader/uefi/stubs.c

@@ -0,0 +1,13 @@
+#define MSG_FMT(msg) "UEFI-STUBS: " msg
+
+#include "common/log.h"
+#include "common/types.h"
+#include "apm.h"
+
+bool services_setup_apm(struct apm_info *out_info)
+{
+    UNUSED(out_info);
+
+    print_warn("APM setup is unsupported!\n");
+    return false;
+}

tests/disk_image.py

@@ -11,6 +11,7 @@
 
 [i686_lower_half]
 protocol=ultra
+setup-apm = true
 
 cmdline    = {cmdline}
 binary     = "/boot/kernel_i686_lower_half"
@@ -37,6 +38,7 @@
 
 [i686_higher_half]
 protocol=ultra
+setup-apm = true
 
 cmdline    = {cmdline}
 binary:
@@ -68,6 +70,7 @@
 
 [amd64_lower_half]
 protocol=ultra
+setup-apm = true
 
 cmdline    = {cmdline}
 binary     = "/boot/kernel_amd64_lower_half"
@@ -94,6 +97,7 @@
 
 [amd64_higher_half]
 protocol=ultra
+setup-apm = true
 
 cmdline = {cmdline}
 binary:
@@ -109,6 +113,7 @@
 
 [amd64_higher_half_5lvl]
 protocol=ultra
+setup-apm = true
 
 cmdline = {cmdline}
 binary:

tests/kernel/kernel.c

@@ -306,6 +306,24 @@ static void validate_modules(struct ultra_module_info_attribute *mi,
     print("modules OK\n");
 }
 
+static void validate_apm_info(struct ultra_apm_attribute *apm)
+{
+    struct ultra_apm_info *info = &apm->info;
+
+    if (info->version < 0x0100)
+        test_fail("bogus APM version 0x%04X\n", info->version);
+    if (!(info->flags & 2))
+        test_fail("bogus APM flags: %d\n", info->flags);
+    if (info->pm_code_segment_length == 0)
+        test_fail("bogus pm code segment length %d\n", info->pm_code_segment_length);
+    if (info->rm_code_segment_length == 0)
+        test_fail("bogus rm code segment length %d\n", info->rm_code_segment_length);
+    if (info->data_segment_length == 0)
+        test_fail("bogus data segment length %d\n", info->data_segment_length);
+
+    print("APM info OK\n");
+}
+
 static void validate_platform_info(struct ultra_platform_info_attribute *pi,
                                    struct ultra_kernel_info_attribute *ki)
 {
@@ -363,6 +381,7 @@ static void attribute_array_verify(struct ultra_boot_context *bctx)
     struct ultra_command_line_attribute *cl = NULL;
     struct ultra_framebuffer_attribute *fb = NULL;
     struct ultra_memory_map_attribute *mm = NULL;
+    struct ultra_apm_attribute *apm_info = NULL;
     struct ultra_module_info_attribute *modules_begin = NULL;
     size_t i, module_count = 0;
     bool modules_eof = false;
@@ -435,6 +454,10 @@ static void attribute_array_verify(struct ultra_boot_context *bctx)
 
             break;
 
+        case ULTRA_ATTRIBUTE_APM_INFO:
+            apm_info = cursor;
+            break;
+
         default:
             test_fail("invalid attribute type %u\n", hdr->type);
         }
@@ -454,6 +477,9 @@ static void attribute_array_verify(struct ultra_boot_context *bctx)
     validate_platform_info(pi, ki);
     validate_modules(modules_begin, module_count, mm, pi);
 
+    if (apm_info)
+        validate_apm_info(apm_info);
+
     print("\nLoader info: %s (version %d.%d) on %s\n",
           pi->loader_name, pi->loader_major, pi->loader_minor,
           platform_to_string(pi->platform_type));