Merge pull request #239 from smartobjectoriented/144-fix-arm32

fix bug added by MUSL support for ARM32

Author: clemdiep

so3/arch/arm32/Makefile

@@ -6,6 +6,7 @@ obj-y += thread.o
 obj-y += vfp.o
 obj-y += backtrace.o backtrace_asm.o
 obj-y += smccc-call.o
+obj-y += syscalls.o
 
 obj-y += lib/
 

so3/arch/arm32/exception.S

@@ -39,7 +39,7 @@
 
 .extern current_thread
 .extern irq_handle
-.extern syscall_handle
+.extern arch_syscall_handle
 
 .extern dumpstack
 
@@ -118,8 +118,8 @@ __prepare_sig_handler:
 	bne	__stack_alignment_fault
 
 	@ Copy TLS to the new stack frame
-	ldr	r0, [sp, #OFFSET_TLS_USR]
-	str	r0, [sp, #(-SVC_STACK_FRAME_SIZE + OFFSET_TLS_USR)]
+	ldr	r1, [sp, #OFFSET_TLS_USR]
+	str	r1, [sp, #(-SVC_STACK_FRAME_SIZE + OFFSET_TLS_USR)]
 
 	str	sp, [sp, #(-SVC_STACK_FRAME_SIZE + OFFSET_SP)]	@ save sp
 
@@ -203,8 +203,8 @@ syscall_interrupt:
 	stmia	lr, {sp, lr}^
 
 	@ Save user space TLS context
-	mrc	p15, 0, r0, c13, c0, 0
-	str 	r0, [sp, #OFFSET_TLS_USR]
+	mrc	p15, 0, lr, c13, c0, 3
+	str 	lr, [sp, #OFFSET_TLS_USR]
 
 	cmp	r7, #SYSCALL_sigreturn
 	beq	__after_push_sp_usr
@@ -223,7 +223,7 @@ __after_push_sp_usr:
 	mov	r0, sp
 
 	cpsie	i 			@ Re-enable interrupts
-	bl	syscall_handle
+	bl	arch_syscall_handle
 	cpsid	i			@ Re-disable interrupts to be safe in regs manipulation
 
 	@ Check if sigreturn has been called. In this case, we
@@ -235,20 +235,22 @@ __after_push_sp_usr:
 	add	sp, sp, #SVC_STACK_FRAME_SIZE
 
 __no_sigreturn:
-__ret_from_fork:
 
 	@ Store the return value on the stack frame
 	cmp	r7, #SYSCALL_sigreturn
 	strne	r0, [sp, #OFFSET_R0]
 
+	// Entry point for new user threads
+ret_from_fork:
+
 #ifdef CONFIG_IPC_SIGNAL
 	@ Is there any pending signals for this process?
 	check_pending_signal
 #endif /* CONFIG_IPC_SIGNAL */
 
 	@ Restore user space TLS context
 	ldr 	lr, [sp, #OFFSET_TLS_USR]
-	mcr	p15, 0, lr, c13, c0, 0
+	mcr	p15, 0, lr, c13, c0, 3
 
 	@ get the saved spsr and adjust the stack pointer
     	ldr 	lr, [sp, #OFFSET_PSR]
@@ -266,14 +268,6 @@ __ret_from_fork:
 
 	ldmia 	sp, {sp, lr, pc}^
 
-
-
-@ Used at entry point of a fork'd process (setting the return value to 0)
-ret_from_fork:
-	mov	r0, #0
-
-	b	__ret_from_fork
-
 .align  5
 prefetch_abort:
 
@@ -360,8 +354,8 @@ irq:
 	stmeqia	lr, {sp, lr}^
 
 	@ Save user space TLS context
-	mrc	p15, 0, r0, c13, c0, 0
-	str 	r0, [sp, #OFFSET_TLS_USR]
+	mrceq	p15, 0, lr, c13, c0, 3
+	streq	lr, [sp, #OFFSET_TLS_USR]
 
 	@ Retrieve the lr_irq to set the pc out of this routine
 	ldr 	lr, [r0, #4]		@ retrieve lr_irq to set lr_svc
@@ -388,10 +382,6 @@ irq:
 	check_pending_signal
 #endif /* CONFIG_IPC_SIGNAL */
 
-	@ Restore user space TLS context
-	ldr 	lr, [sp, #OFFSET_TLS_USR]
-	mcr	p15, 0, lr, c13, c0, 0
-
     	ldr 	lr, [sp, #OFFSET_PSR]	@ get the saved spsr and adjust the stack pointer
     	msr	spsr, lr
 
@@ -403,6 +393,10 @@ irq:
 	addeq	lr, sp, #OFFSET_SP_USR
 	ldmeqia	lr, {sp, lr}^
 
+	@ Restore user space TLS context
+	ldreq	lr, [sp, #OFFSET_TLS_USR]
+	mcreq	p15, 0, lr, c13, c0, 3
+
 	@ Restore registers
    	ldmia 	sp, {r0-r12}
 

so3/arch/arm32/syscalls.c

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2026 Dieperink Clément <clement.dieperink@heig-vd.ch>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#include <syscall.h>
+#include <thread.h>
+#include <process.h>
+
+/* ARM32 specific syscalls to manage TLS */
+#define ARM_NR_set_tls 0x0f0005
+#define ARM_NR_get_tls 0x0f0006
+
+extern void __get_syscall_args_ext(long *syscall_no);
+
+/**
+ * Handle special ARM32 syscalls, or fallback to generic syscall handling.
+ */
+long arch_syscall_handle(syscall_args_t *syscall_args)
+{
+	long syscall_no;
+	cpu_regs_t *user_regs = (cpu_regs_t *) arch_get_kernel_stack_frame(current());
+
+	/* Get addtional args of the syscall according to the ARM & SO3 ABI */
+	__get_syscall_args_ext(&syscall_no);
+
+	switch (syscall_no) {
+	case ARM_NR_get_tls:
+		return user_regs->tls_usr;
+	case ARM_NR_set_tls:
+		user_regs->tls_usr = syscall_args->args[0];
+		return 0;
+	default:
+		return syscall_handle(syscall_args);
+	}
+}

so3/arch/arm32/thread.c

@@ -55,6 +55,12 @@ void arch_prepare_cpu_regs(tcb_t *tcb, clone_args_t *args)
 
 			if (args->flags & CLONE_SETTLS)
 				user_regs->tls_usr = args->tls;
+
+			/* Set return value to 0 to indicate new thread */
+			user_regs->r0 = 0;
+
+			/* Set kernel stack address used to restore stack on eret */
+			user_regs->sp = get_kernel_stack_top(tcb->stack_slotID);
 		}
 
 		tcb->cpu_regs.lr = (unsigned long) ret_from_fork;
@@ -79,8 +85,9 @@ void arch_restart_user_thread(tcb_t *tcb, th_fn_t fn_entry, addr_t stack_top)
 	 */
 	*user_regs = (cpu_regs_t) {
 		.pc = (u32) fn_entry,
-		.psr = PSR_USR_MODE,
+		.psr = PSR_USR_MODE | PSR_I_BIT,
 		.sp_usr = stack_top,
+		.sp = get_kernel_stack_top(tcb->stack_slotID),
 	};
 }
 

so3/arch/arm64/exception.S

@@ -567,13 +567,13 @@ el01_sync_handler:
 	// Check if sigreturn has been called. In this case, we
 	// clean the stack frame which has been used to manage the user handler.
 	cmp	x8, #SYSCALL_rt_sigreturn
-	bne	__ret_from_fork
+	bne	ret_from_fork
 
 	// Reset the stack frame by removing the one issued from sigreturn
 	add	sp, sp, #S_FRAME_SIZE
 
-
-__ret_from_fork:
+	// Entry point for new user threads
+ret_from_fork:
 
 #ifdef CONFIG_IPC_SIGNAL
 	// Is there any pending signals for this process?
@@ -605,11 +605,6 @@ el01_1_irq_handler:
 
 	eret
 
-// Used at entry point of a fork'd process (setting the return value to 0)
-ret_from_fork:
-	str	xzr, [sp, #OFFSET_X0]
-	b	__ret_from_fork
-
 #if !defined(CONFIG_AVZ) && defined(CONFIG_SOO)
 
 .align 5

so3/arch/arm64/thread.c

@@ -54,6 +54,9 @@ void arch_prepare_cpu_regs(tcb_t *tcb, clone_args_t *args)
 
 			if (args->flags & CLONE_SETTLS)
 				user_regs->tls_usr = args->tls;
+
+			/* Set return value to 0 to indicate new thread */
+			user_regs->x0 = 0;
 		}
 
 		tcb->cpu_regs.lr = (unsigned long) ret_from_fork;

so3/devices/serial.c

@@ -100,38 +100,8 @@ int serial_write(char *str, int len)
 /* This function will query the size of the serial terminal*/
 int serial_gwinsize(struct winsize *wsz)
 {
-	/*
-	 * The following code strongly depends on a patched version of QEMU which reacts
-	 * to the '\254' ASCII code. When the emulated UART interface get this code, qemu
-	 * queries the host via ioctl(stdout, TIOCGWINSZ) to retrieve the window size.
-	 */
-
-	/* We want to reserve the access to the uart read. */
-
-	/* Prevent an interrupt on the UART generated by
-	 * QEMU to read the two bytes. So far, we do not
-	 * manage an internal buffer to read many chars.
-	 */
-
-#if defined(CONFIG_VIRT32) && !defined(CONFIG_SOO)
-
-	serial_ops.disable_irq();
-
-	if (serial_write(SERIAL_GWINSZ, 1) == 0)
-		return -1;
-
-	wsz->ws_row = serial_ops.get_byte(true);
-	wsz->ws_col = serial_ops.get_byte(true);
-
-	serial_ops.enable_irq();
-
-#else
-
 	wsz->ws_row = WINSIZE_ROW_SIZE_DEFAULT;
 	wsz->ws_col = WINSIZE_COL_SIZE_DEFAULT;
-
-#endif
-
 	return 0;
 }
 

so3/fs/elf.c

@@ -165,6 +165,8 @@ void elf_load_sections(elf_img_info_t *elf_img_info)
 void elf_load_segments(elf_img_info_t *elf_img_info)
 {
 	size_t i;
+	size_t segment_start, segment_end;
+	size_t page_start, page_end;
 
 	/* Segments */
 #ifdef CONFIG_ARCH_ARM32
@@ -199,8 +201,16 @@ void elf_load_segments(elf_img_info_t *elf_img_info)
 		       sizeof(struct elf64_phdr));
 #endif
 
-		if (elf_img_info->segments[i].p_type == PT_LOAD)
-			elf_img_info->segment_page_count += (elf_img_info->segments[i].p_memsz >> PAGE_SHIFT) + 1;
+		if (elf_img_info->segments[i].p_type == PT_LOAD) {
+			/* Don't use only p_memsz to get page count as p_vaddr can be unaligned and additionnal page will be needed. */
+			segment_start = elf_img_info->segments[i].p_vaddr;
+			segment_end = segment_start + elf_img_info->segments[i].p_memsz;
+
+			page_start = segment_start >> PAGE_SHIFT;
+			page_end = (segment_end + PAGE_SIZE) >> PAGE_SHIFT;
+
+			elf_img_info->segment_page_count += page_end - page_start;
+		}
 	}
 	LOG_DEBUG("segments use %d virtual pages\n", elf_img_info->segment_page_count);
 

so3/include/device/timer.h

@@ -49,6 +49,13 @@ struct timeval32 {
 	time32_t tv_usec; /* microseconds */
 };
 
+/* Time conversion units - Dynamic size (for nanosleep syscall). */
+
+struct long_timespec {
+	long tv_sec; /* seconds */
+	long tv_nsec; /* nanoseconds */
+};
+
 /* All timing information below must be express in nanoseconds. The underlying hardware is responsible
  * to perform the necessary alignment on 64 bits. */
 

so3/include/timer.h

@@ -126,7 +126,7 @@ void clocksource_timer_reset(void);
 
 void clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec);
 
-SYSCALL_DECLARE(nanosleep, const struct timespec *req, struct timespec *rem);
+SYSCALL_DECLARE(nanosleep, const struct long_timespec *req, struct long_timespec *rem);
 
 SYSCALL_DECLARE(gettimeofday_time32, struct timeval32 *tv, void *tz);
 SYSCALL_DECLARE(gettimeofday, struct timeval *tv, void *tz);