From 5d686229e8f808c65934c17da9313e758b4ef9e9 Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Tue, 27 Jan 2015 15:40:47 -0800 Subject: [PATCH] elog: Correct behavior when FMAP section doesn't exist on ChromeOS The elog driver has a really stupid bug that checks a result which is stored in an unsigned variable for < 0. Surprisingly GCC does not catch this nonsense right now, and I spent an hour trying out different warning options without finding one that doesn't also bring a load of stupid and unavoidable false positives (the biggest offender being -Wtype-limits, which does exactly what we'd want except for flagging things like if ((u8)var >= CONFIG_VAR_MIN) where the VAR_MIN Kconfig may or may not be 0). So, the only thing we can do is fix this one and wait for the next time something like that blows up. -.- Also change some more code to make the behavior more explicit (the old code already intended to work this way since flash_base is statically initialized to 0, never assigned in the error path and checked later in elog_init()... but there was an error message that incorrectly claimed a different fallback behavior, and explicitly assigning the values makes this easier to see). Finally, add another state to the elog_initialized variable to avoid trying to reinitialize a broken eventlog on every event (if it doesn't work the first time, chances are that it won't work later on during the same boot either). BRANCH=None BUG=chrome-os-partner:35940 TEST=Flashed Jerry with RO 6588.4 and RW 6588.23, observed how it now cleanly enters recovery mode without blowing its bootblock away with stray eventlog entries. Change-Id: I0e5348ba961ce4835c30f7108a2453522095f2ee Signed-off-by: Stefan Reinauer Original-Commit-Id: f9798dbf0c2b2e337062ecd84d0f45434343c0d9 Original-Change-Id: I4d93f48d2d01d75a04550d419e023aa42ca95a7a Original-Signed-off-by: Julius Werner Original-Reviewed-on: https://chromium-review.googlesource.com/243671 Original-Reviewed-by: Duncan Laurie Reviewed-on: http://review.coreboot.org/9557 Tested-by: build bot (Jenkins) Reviewed-by: Julius Werner Reviewed-by: Patrick Georgi --- src/drivers/elog/elog.c | 38 +++++++++++++++++++++----------------- 1 file changed, 21 insertions(+), 17 deletions(-) diff --git a/src/drivers/elog/elog.c b/src/drivers/elog/elog.c index f6b0006db8..76e8cf71b8 100644 --- a/src/drivers/elog/elog.c +++ b/src/drivers/elog/elog.c @@ -75,9 +75,13 @@ static elog_event_buffer_state event_buffer_state; static u16 next_event_offset; static u16 event_count; -static int elog_initialized; static struct spi_flash *elog_spi; +static enum { + ELOG_UNINITIALIZED = 0, + ELOG_INITIALIZED, + ELOG_BROKEN, +} elog_initialized = ELOG_UNINITIALIZED; static inline u32 get_rom_size(void) { @@ -522,25 +526,18 @@ int elog_clear(void) static void elog_find_flash(void) { -#if CONFIG_CHROMEOS - u8 *flash_base_ptr; -#endif - elog_debug("elog_find_flash()\n"); #if CONFIG_CHROMEOS /* Find the ELOG base and size in FMAP */ - total_size = find_fmap_entry("RW_ELOG", (void **)&flash_base_ptr); - if (total_size < 0) { - printk(BIOS_WARNING, "ELOG: Unable to find RW_ELOG in FMAP, " - "using CONFIG_ELOG_FLASH_BASE instead\n"); - total_size = CONFIG_ELOG_AREA_SIZE; + u8 *flash_base_ptr; + int fmap_size = find_fmap_entry("RW_ELOG", (void **)&flash_base_ptr); + if (fmap_size < 0) { + printk(BIOS_WARNING, "ELOG: Unable to find RW_ELOG in FMAP\n"); + flash_base = total_size = 0; } else { flash_base = elog_flash_address_to_offset(flash_base_ptr); - - /* Use configured size if smaller than FMAP size */ - if (total_size > CONFIG_ELOG_AREA_SIZE) - total_size = CONFIG_ELOG_AREA_SIZE; + total_size = MIN(fmap_size, CONFIG_ELOG_AREA_SIZE); } #else flash_base = CONFIG_ELOG_FLASH_BASE; @@ -554,8 +551,15 @@ static void elog_find_flash(void) */ int elog_init(void) { - if (elog_initialized) + switch (elog_initialized) { + case ELOG_UNINITIALIZED: + break; + case ELOG_INITIALIZED: return 0; + case ELOG_BROKEN: + return -1; + } + elog_initialized = ELOG_BROKEN; elog_debug("elog_init()\n"); @@ -600,8 +604,6 @@ int elog_init(void) return -1; } - elog_initialized = 1; - printk(BIOS_INFO, "ELOG: FLASH @0x%p [SPI 0x%08x]\n", elog_area, flash_base); @@ -637,6 +639,8 @@ int elog_init(void) #endif #endif + elog_initialized = ELOG_INITIALIZED; + return 0; }