From 22069215eb7adf5a3888bf7c7784ea9d70a72cd0 Mon Sep 17 00:00:00 2001 From: Shinya Kuribayashi Date: Sun, 21 Oct 2007 10:55:36 +0900 Subject: [MIPS] Fix $gp usage Now we load $gp with _GLOBAL_OFFSET_TABLE_, but this is incorrect use. As a general principle, we should use _gp for $gp. Thanks to linker script's help we fortunately have _gp which equals to _GLOBAL_OFFSET_TABLE_. But once _gp gets out of alignment, we will not be able to access to GOT entires, global variables and procedure entry points. The right thing to do is to use _gp. This patch also introduce a new symbol `.gpword _GLOBAL_OFFSET_TABLE_' which holds the offset from _gp. When updating GOT entries, we use this offset and _gp to calculate the final _GLOBAL_OFFSET_TABLE_. This patch is originally submitted by Vlad Lungu , then I made some change to leave over num_got_entries. Signed-off-by: Shinya Kuribayashi Cc: Vlad Lungu --- cpu/mips/start.S | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) (limited to 'cpu/mips/start.S') diff --git a/cpu/mips/start.S b/cpu/mips/start.S index e91e213..074d01d 100644 --- a/cpu/mips/start.S +++ b/cpu/mips/start.S @@ -234,11 +234,11 @@ reset: li t0, CONF_CM_UNCACHED mtc0 t0, CP0_CONFIG - /* Initialize GOT pointer. + /* Initialize $gp. */ bal 1f nop - .word _GLOBAL_OFFSET_TABLE_ + .word _gp 1: move gp, ra lw t1, 0(ra) @@ -306,9 +306,9 @@ relocate_code: move t1, a2 /* - * Fix GOT pointer: + * Fix $gp: * - * New GOT-PTR = (old GOT-PTR - CFG_MONITOR_BASE) + Destination Address + * New $gp = (Old $gp - CFG_MONITOR_BASE) + Destination Address */ move t6, gp sub gp, CFG_MONITOR_BASE @@ -341,15 +341,22 @@ relocate_code: j t0 nop + .gpword _GLOBAL_OFFSET_TABLE_ /* _GLOBAL_OFFSET_TABLE_ - _gp */ .word uboot_end_data .word uboot_end .word num_got_entries in_ram: - /* Now we want to update GOT. + /* + * Now we want to update GOT. + * + * GOT[0] is reserved. GOT[1] is also reserved for the dynamic object + * generated by GNU ld. Skip these reserved entries from relocation. */ lw t3, -4(t0) /* t3 <-- num_got_entries */ - addi t4, gp, 8 /* Skipping first two entries. */ + lw t4, -16(t0) /* t4 <-- (_GLOBAL_OFFSET_TABLE_ - _gp) */ + add t4, t4, gp /* t4 now holds _GLOBAL_OFFSET_TABLE_ */ + addi t4, t4, 8 /* Skipping first two entries. */ li t2, 2 1: lw t1, 0(t4) -- cgit v1.1 From 03c031d5660ea946c39af6e2e16267da857c609f Mon Sep 17 00:00:00 2001 From: Shinya Kuribayashi Date: Sat, 27 Oct 2007 15:27:06 +0900 Subject: [MIPS] MIPS 4K core: Coding style cleanups No logical changes. Signed-off-by: Shinya Kuribayashi --- cpu/mips/start.S | 50 +++++++++++++++++++++++--------------------------- 1 file changed, 23 insertions(+), 27 deletions(-) (limited to 'cpu/mips/start.S') diff --git a/cpu/mips/start.S b/cpu/mips/start.S index 074d01d..5a278b6 100644 --- a/cpu/mips/start.S +++ b/cpu/mips/start.S @@ -22,13 +22,11 @@ * MA 02111-1307 USA */ - #include #include #include #include - #define RVECENT(f,n) \ b f; nop #define XVECENT(f,bev) \ @@ -192,7 +190,7 @@ _start: .word 0x00000000 .word 0x03e00008 .word 0x00000000 - .word 0x00000000 + .word 0x00000000 /* 0xbfc00428 */ .word 0xdc870000 .word 0xfca70000 @@ -203,7 +201,7 @@ _start: .word 0x00000000 .word 0x03e00008 .word 0x00000000 - .word 0x00000000 + .word 0x00000000 #endif /* CONFIG_PURPLE */ .align 4 reset: @@ -235,33 +233,33 @@ reset: mtc0 t0, CP0_CONFIG /* Initialize $gp. - */ - bal 1f + */ + bal 1f nop .word _gp - 1: - move gp, ra - lw t1, 0(ra) +1: + move gp, ra + lw t1, 0(ra) move gp, t1 #ifdef CONFIG_INCA_IP /* Disable INCA-IP Watchdog. */ - la t9, disable_incaip_wdt - jalr t9 + la t9, disable_incaip_wdt + jalr t9 nop #endif /* Initialize any external memory. */ - la t9, lowlevel_init - jalr t9 + la t9, lowlevel_init + jalr t9 nop /* Initialize caches... */ - la t9, mips_cache_reset - jalr t9 + la t9, mips_cache_reset + jalr t9 nop /* ... and enable them. @@ -269,12 +267,11 @@ reset: li t0, CONF_CM_CACHABLE_NONCOHERENT mtc0 t0, CP0_CONFIG - /* Set up temporary stack. */ li a0, CFG_INIT_SP_OFFSET - la t9, mips_cache_lock - jalr t9 + la t9, mips_cache_lock + jalr t9 nop li t0, CFG_SDRAM_BASE + CFG_INIT_SP_OFFSET @@ -284,7 +281,6 @@ reset: j t9 nop - /* * void relocate_code (addr_sp, gd, addr_moni) * @@ -298,7 +294,7 @@ reset: .globl relocate_code .ent relocate_code relocate_code: - move sp, a0 /* Set new stack pointer */ + move sp, a0 /* Set new stack pointer */ li t0, CFG_MONITOR_BASE la t3, in_ram @@ -312,8 +308,8 @@ relocate_code: */ move t6, gp sub gp, CFG_MONITOR_BASE - add gp, a2 /* gp now adjusted */ - sub t6, gp, t6 /* t6 <-- relocation offset */ + add gp, a2 /* gp now adjusted */ + sub t6, gp, t6 /* t6 <-- relocation offset */ /* * t0 = source address @@ -329,7 +325,7 @@ relocate_code: sw t3, 0(t1) addu t0, 4 ble t0, t2, 1b - addu t1, 4 /* delay slot */ + addu t1, 4 /* delay slot */ #endif /* If caches were enabled, we would have to flush them here. @@ -376,7 +372,8 @@ in_ram: add t2, t6 sub t1, 4 -1: addi t1, 4 +1: + addi t1, 4 bltl t1, t2, 1b sw zero, 0(t1) /* delay slot */ @@ -387,11 +384,10 @@ in_ram: .end relocate_code - /* Exception handlers. */ romReserved: - b romReserved + b romReserved romExcHandle: - b romExcHandle + b romExcHandle -- cgit v1.1 From 16664f72850846e645616da1c0fa5afcd6d15f15 Mon Sep 17 00:00:00 2001 From: Shinya Kuribayashi Date: Sat, 17 Nov 2007 20:05:26 +0900 Subject: [MIPS] Remove useless instructions for initializing $gp. Signed-off-by: Shinya Kuribayashi --- cpu/mips/start.S | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'cpu/mips/start.S') diff --git a/cpu/mips/start.S b/cpu/mips/start.S index 5a278b6..c92b162 100644 --- a/cpu/mips/start.S +++ b/cpu/mips/start.S @@ -238,9 +238,7 @@ reset: nop .word _gp 1: - move gp, ra - lw t1, 0(ra) - move gp, t1 + lw gp, 0(ra) #ifdef CONFIG_INCA_IP /* Disable INCA-IP Watchdog. -- cgit v1.1