lkmc_vector_equal into lkmc.c

Document lkmc.c

README.adoc

@@ -12990,6 +12990,23 @@ ls /mnt/9p/rootfs_overlay
 
 This way you can just hack away the scripts and try them out immediately without any further operations.
 
+==== lkmc.c
+
+The files:
+
+* link:lkmc.c[]
+* link:lkmc.h[]
+
+contain common C function helpers that can be used both in userland and baremetal. Oh, the infinite <<about-the-baremetal-setup,joys of Newlib>>.
+
+Those files also contain arch specific helpers under ifdefs like:
+
+....
+#if defined(__aarch64__)
+....
+
+We try to keep as much as possible in those files. It bloats builds a little, but just makes everything simpler to understand.
+
 === Test this repo
 
 ==== Automated tests

baremetal/lib/aarch64.S

@@ -23,7 +23,7 @@ LKMC_VECTOR_TABLE
 
 /* Default trap handler that does nothing.
  *
- * Weak means that if any other file deinfes it as a non-weak global,
+ * Weak means that if any other file defines it as a non-weak global,
  * that one will take precedence.
  *
  * We need this one to not get undefined references.

build-baremetal

@@ -19,9 +19,7 @@ Build the baremetal examples with crosstool-NG.
     def build(self):
         build_dir = self.get_build_dir()
         bootloader_obj = os.path.join(self.env['baremetal_build_lib_dir'], 'bootloader{}'.format(self.env['obj_ext']))
-        common_basename_noext = 'lkmc'
+        common_obj = os.path.join(self.env['baremetal_build_lib_dir'], self.env['common_basename_noext'] + self.env['obj_ext'])
-        common_src = os.path.join(self.env['root_dir'], common_basename_noext + self.env['c_ext'])
-        common_obj = os.path.join(self.env['baremetal_build_lib_dir'], common_basename_noext + self.env['obj_ext'])
         syscalls_basename_noext = 'syscalls'
         syscalls_src = os.path.join(self.env['baremetal_source_lib_dir'], syscalls_basename_noext + self.env['c_ext'])
         syscalls_obj = os.path.join(self.env['baremetal_build_lib_dir'], syscalls_basename_noext + self.env['obj_ext'])
@@ -34,6 +32,7 @@ Build the baremetal examples with crosstool-NG.
             '-mcpu={}'.format(self.env['mcpu']), LF,
             '-nostartfiles', LF,
         ]
+        cflags_after = ['-lm']
         gcc = self.get_toolchain_tool('gcc')
         if self.env['emulator'] == 'gem5':
             if self.env['machine'] == 'VExpress_GEM5_V1':
@@ -59,10 +58,11 @@ Build the baremetal examples with crosstool-NG.
                     '-c', LF,
                     '-o', bootloader_obj, LF,
                     src, LF,
-                ]
+                ] +
+                cflags_after
             )
         for src, obj in [
-            (common_src, common_obj),
+            (self.env['common_c'], common_obj),
             (syscalls_src, syscalls_obj),
         ]:
             if self.need_rebuild([src], obj):
@@ -74,12 +74,14 @@ Build the baremetal examples with crosstool-NG.
                         '-D', 'UART0_ADDR={:#x}'.format(uart_address), LF,
                         '-o', obj, LF,
                         src, LF,
-                    ]
+                    ] +
+                    cflags_after
                 )
         self._build_dir(
             '',
             gcc=gcc,
             cflags=cflags,
+            cflags_after=cflags_after,
             entry_address=entry_address,
             bootloader_obj=bootloader_obj,
             common_objs=common_objs,
@@ -88,6 +90,7 @@ Build the baremetal examples with crosstool-NG.
             'interactive',
             gcc=gcc,
             cflags=cflags,
+            cflags_after=cflags_after,
             entry_address=entry_address,
             bootloader_obj=bootloader_obj,
             common_objs=common_objs,
@@ -97,6 +100,7 @@ Build the baremetal examples with crosstool-NG.
                 self.env['baremetal_source_arch_subpath'],
                 gcc=gcc,
                 cflags=cflags,
+                cflags_after=cflags_after,
                 entry_address=entry_address,
                 bootloader_obj=bootloader_obj,
                 common_objs=common_objs,
@@ -107,6 +111,7 @@ Build the baremetal examples with crosstool-NG.
                 arch_dir,
                 gcc=gcc,
                 cflags=cflags,
+                cflags_after=cflags_after,
                 entry_address=entry_address,
                 bootloader_obj=bootloader_obj,
                 common_objs=common_objs,
@@ -121,6 +126,7 @@ Build the baremetal examples with crosstool-NG.
             subpath,
             gcc,
             cflags,
+            cflags_after,
             entry_address,
             bootloader_obj,
             common_objs,
@@ -152,7 +158,8 @@ Build the baremetal examples with crosstool-NG.
                             '-c', LF,
                             '-o', main_obj, LF,
                             src, LF,
-                        ]
+                        ] +
+                        cflags_after
                     )
                 objs = common_objs + [main_obj]
                 out = os.path.join(self.env['baremetal_build_dir'], subpath, in_name + self.env['baremetal_build_ext'])
@@ -166,7 +173,8 @@ Build the baremetal examples with crosstool-NG.
                             '-o', out, LF,
                             '-T', link_script, LF,
                         ] +
-                        self.sh.add_newlines(objs)
+                        self.sh.add_newlines(objs) +
+                        cflags_after
                     )
 
 if __name__ == '__main__':

common.py

@@ -726,6 +726,17 @@ Valid emulators: {}
         env['baremetal_build_lib_dir'] = join(env['baremetal_build_dir'], env['baremetal_lib_basename'])
         env['baremetal_build_ext'] = '.elf'
 
+        # Userland / baremetal common source.
+        env['common_basename_noext'] = 'lkmc'
+        env['common_c'] = common_c = os.path.join(
+            env['root_dir'],
+            env['common_basename_noext'] + env['c_ext']
+        )
+        env['common_h'] = common_c = os.path.join(
+            env['root_dir'],
+            env['common_basename_noext'] + env['header_ext']
+        )
+
         # Docker
         env['docker_build_dir'] = join(env['out_dir'], 'docker', env['arch'])
         env['docker_tar_dir'] = join(env['docker_build_dir'], 'export')

lkmc.c

@@ -1,3 +1,6 @@
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#lkmc-c */
+
+#include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -9,8 +12,21 @@ void lkmc_assert(bool condition) {
 }
 
 void lkmc_assert_fail() {
-	puts("lkmc_test_fail");
+    puts("lkmc_test_fail");
-	exit(1);
+    exit(1);
+}
+
+bool lkmc_vector_equal(size_t n, double *v1, double *v2, double max_err) {
+    double sum = 0.0;
+    double diff;
+    size_t i;
+    for (i = 0; i < n; ++i) {
+        diff = v1[i] - v2[i];
+        sum += diff * diff;
+    }
+    if (sqrt(sum)/n > max_err)
+        return false;
+    return true;
 }
 
 #if defined(__aarch64__)

lkmc.h

@@ -1,13 +1,17 @@
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#lkmc-c */
+
 #ifndef LKMC_H
 #define LKMC_H
 
 /* Common C definitions. */
 #if !defined(__ASSEMBLER__)
-#include <stdbool.h>
 #include <inttypes.h>
+#include <stdbool.h>
+#include <stdlib.h>
 
 void lkmc_assert(bool);
 void lkmc_assert_fail();
+bool lkmc_vector_equal(size_t n, double *v1, double *v2, double max_err);
 #endif
 
 /* https://stackoverflow.com/questions/1489932/how-to-concatenate-twice-with-the-c-preprocessor-and-expand-a-macro-as-in-arg */

userland/common_userland.h

@@ -3,23 +3,20 @@
 
 #define _XOPEN_SOURCE 700
 #include <fcntl.h> /* open */
-#include <math.h> /* fabs */
 #include <stdint.h> /* uint64_t  */
-#include <stdlib.h> /* size_t */
 #include <stdio.h> /* snprintf */
 #include <sys/types.h>
 #include <unistd.h> /* pread, sysconf */
-#include <stdbool.h>
 
 /* Format documented at:
  * https://github.com/torvalds/linux/blob/v4.9/Documentation/vm/pagemap.txt
  */
 typedef struct {
-	uint64_t pfn : 54;
+    uint64_t pfn : 54;
-	unsigned int soft_dirty : 1;
+    unsigned int soft_dirty : 1;
-	unsigned int file_page : 1;
+    unsigned int file_page : 1;
-	unsigned int swapped : 1;
+    unsigned int swapped : 1;
-	unsigned int present : 1;
+    unsigned int present : 1;
 } PagemapEntry;
 
 /* Parse the pagemap entry for the given virtual address.
@@ -31,31 +28,31 @@ typedef struct {
  */
 int pagemap_get_entry(PagemapEntry *entry, int pagemap_fd, uintptr_t vaddr)
 {
-	size_t nread;
+    size_t nread;
-	ssize_t ret;
+    ssize_t ret;
-	uint64_t data;
+    uint64_t data;
-	uintptr_t vpn;
+    uintptr_t vpn;
 
-	vpn = vaddr / sysconf(_SC_PAGE_SIZE);
+    vpn = vaddr / sysconf(_SC_PAGE_SIZE);
-	nread = 0;
+    nread = 0;
-	while (nread < sizeof(data)) {
+    while (nread < sizeof(data)) {
-		ret = pread(
+        ret = pread(
-			pagemap_fd,
+            pagemap_fd,
-			&data,
+            &data,
-			sizeof(data) - nread,
+            sizeof(data) - nread,
-			vpn * sizeof(data) + nread
+            vpn * sizeof(data) + nread
-		);
+        );
-		nread += ret;
+        nread += ret;
-		if (ret <= 0) {
+        if (ret <= 0) {
-			return 1;
+            return 1;
-		}
+        }
-	}
+    }
-	entry->pfn = data & (((uint64_t)1 << 54) - 1);
+    entry->pfn = data & (((uint64_t)1 << 54) - 1);
-	entry->soft_dirty = (data >> 54) & 1;
+    entry->soft_dirty = (data >> 54) & 1;
-	entry->file_page = (data >> 61) & 1;
+    entry->file_page = (data >> 61) & 1;
-	entry->swapped = (data >> 62) & 1;
+    entry->swapped = (data >> 62) & 1;
-	entry->present = (data >> 63) & 1;
+    entry->present = (data >> 63) & 1;
-	return 0;
+    return 0;
 }
 
 /* Convert the given virtual address to physical using /proc/PID/pagemap.
@@ -67,35 +64,21 @@ int pagemap_get_entry(PagemapEntry *entry, int pagemap_fd, uintptr_t vaddr)
  */
 int virt_to_phys_user(uintptr_t *paddr, pid_t pid, uintptr_t vaddr)
 {
-	char pagemap_file[BUFSIZ];
+    char pagemap_file[BUFSIZ];
-	int pagemap_fd;
+    int pagemap_fd;
 
-	snprintf(pagemap_file, sizeof(pagemap_file), "/proc/%ju/pagemap", (uintmax_t)pid);
+    snprintf(pagemap_file, sizeof(pagemap_file), "/proc/%ju/pagemap", (uintmax_t)pid);
-	pagemap_fd = open(pagemap_file, O_RDONLY);
+    pagemap_fd = open(pagemap_file, O_RDONLY);
-	if (pagemap_fd < 0) {
+    if (pagemap_fd < 0) {
-		return 1;
+        return 1;
-	}
+    }
-	PagemapEntry entry;
+    PagemapEntry entry;
-	if (pagemap_get_entry(&entry, pagemap_fd, vaddr)) {
+    if (pagemap_get_entry(&entry, pagemap_fd, vaddr)) {
-		return 1;
+        return 1;
-	}
+    }
-	close(pagemap_fd);
+    close(pagemap_fd);
-	*paddr = (entry.pfn * sysconf(_SC_PAGE_SIZE)) + (vaddr % sysconf(_SC_PAGE_SIZE));
+    *paddr = (entry.pfn * sysconf(_SC_PAGE_SIZE)) + (vaddr % sysconf(_SC_PAGE_SIZE));
-	return 0;
+    return 0;
-}
-
-bool common_vector_equal(size_t n, double * v1, double * v2, double max_err)
-{
-	double sum = 0.0;
-	double diff;
-	size_t i;
-	for (i = 0; i < n; ++i) {
-		diff = v1[i] - v2[i];
-		sum += diff * diff;
-	}
-	if (sqrt(sum)/n > max_err)
-		return false;
-	return true;
 }
 
 #endif

userland/openblas_hello.c

@@ -1,16 +1,15 @@
 /* https://github.com/cirosantilli/linux-kernel-module-cheat#blas
  * Adapted from: https://github.com/xianyi/OpenBLAS/wiki/User-Manual/59b62f98e7400270fb03ad1d85fba5b64ebbff2b#call-cblas-interface */
 
-#include "common_userland.h"
+#include "lkmc.h"
 
 #include <assert.h>
 #include <cblas.h>
 
-int main(void)
+int main(void) {
-{
+    double A[6] = {1.0, 2.0, 1.0, -3.0, 4.0, -1.0};
-	double A[6] = {1.0, 2.0, 1.0, -3.0, 4.0, -1.0};
+    double B[6] = {1.0, 2.0, 1.0, -3.0, 4.0, -1.0};
-	double B[6] = {1.0, 2.0, 1.0, -3.0, 4.0, -1.0};
+    double C[9] = {0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5};
-	double C[9] = {0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5};
+    cblas_dgemm(CblasColMajor, CblasNoTrans, CblasTrans, 3, 3, 2, 1, A, 3, B, 3, 2, C, 3);
-	cblas_dgemm(CblasColMajor, CblasNoTrans, CblasTrans, 3, 3, 2, 1, A, 3, B, 3, 2, C, 3);
+    assert(lkmc_vector_equal(9, C, (double[]){11.0, -9.0, 5.0, -9.0, 21.0, -1.0, 5.0, -1.0, 3.0}, 1e-6));
-	assert(common_vector_equal(9, C, (double[]){11.0, -9.0, 5.0, -9.0, 21.0, -1.0, 5.0, -1.0, 3.0}, 1e-6));
 }